JP2023507715A - Composite gypsum board formed from high salt stucco and related methods - Google Patents

Abstract

A composite gypsum board and a method of making the gypsum board are disclosed. The board contains at least one layer of set gypsum sandwiched between a front coversheet and a back coversheet. The set gypsum layer is formed from at least stucco and water. Stucco materials generally contain high salt impurity content, for example when the stucco is fired from certain sources of low quality synthetic gypsum. For example, in some embodiments the salt is a chloride salt, such as sodium chloride (NaCl), potassium chloride (KCl), magnesium chloride (MgCl2), and/or calcium chloride (CaCl2). The board and method improve bonding between the gypsum layer and at least one of the cover sheets (eg, the back cover sheet). Methods and systems related to drying gypsum board are also provided. [Selection drawing] Fig. 1

Description

Set gypsum is a well-known material used in many products, including panels and other products for building construction and renovation. One such panel (often referred to as gypsum board) is in the form of a set gypsum core sandwiched between two cover sheets (e.g., paper board) and is used for dry plastering of building interior walls and ceilings. Commonly used in wall construction. One or more dense layers, often referred to as "skim coats", may be included on either side of the core, usually at the paper-core interface.

Gypsum (calcium sulfate dihydrate) occurs naturally and can be mined in rock form. It may also be in synthetic form (referred to in the art as "syngyp") as a by-product of industrial processes such as flue gas desulfurization. calcining gypsum from any source (natural or synthetic) at high temperatures to form stucco (i.e., calcined gypsum in the form of calcium sulfate hemihydrate and/or calcium sulfate free) followed by rehydration; to form set gypsum in a desired shape (eg, as a board). During manufacture of the board, the stucco, water, and optionally other ingredients are mixed in a mixer. A slurry is formed and discharged from the mixer onto a moving conveyor that carries the coversheet to which one of the skim coats (if any) has already been applied (often upstream of the mixer). The slurry is spread on paper (a skim coat is optionally included on the paper). Another cover sheet, with or without a skim coat, is applied over the slurry to form a sandwich structure of desired thickness using, for example, forming plates. The mixture is cast and allowed to set to form set (ie, rehydrated) gypsum by reaction of gypsum of Paris with water to form a matrix of crystalline hydrated gypsum (ie, calcium sulfate dihydrate). It is the desired hydration of the calcined gypsum that allows the formation of an interlocking matrix of set gypsum crystals, thereby imparting strength to the gypsum structure in the product. Heat is required (eg, in a kiln) to remove remaining free (ie, unreacted) water and obtain a dry product.

Gypsum (calcium sulfate dihydrate and any impurities) suitable for use in wallboard may be obtained from both natural and synthetic sources and then further processed.

Natural gypsum may be used by calcining its calcium sulfate dihydrate to produce the hemihydrate form. Gypsum from natural sources is a naturally occurring mineral that can be mined in rock form. Naturally occurring gypsum is a mineral typically found in ancient salt lake formations, volcanic deposits, and clay formations. When mined, raw gypsum is commonly found in the dihydrate form. Gypsum is also known as calcium sulfate dihydrate, terra alba or land plaster. This material is also produced as a by-product of various industrial processes. For example, synthetic gypsum is a by-product of the flue gas desulfurization process from power plants. In gypsum there are approximately two molecules of water associated with each molecule of calcium sulfate.

Plaster of Paris is calcined gypsum, stucco, calcium sulfate hemihydrate, calcium sulfate half-hydrate, or calcium sulfate hemihydrate is also known as

When calcium sulfate dihydrate from any source is heated sufficiently in a process called calcination or calcination, the water of hydration is at least partially driven off and, depending on temperature and exposure time, calcium sulfate It can form either the hemihydrate ( _CaSO4.1 / _2H2O ) (typically provided in materials commonly referred to as "stucco") or calcium sulfate anhydrite ( _CaSO4 ). can. As used herein, the terms "stucco" and "plaster of paris" refer to both the hemihydrate and anhydrous gypsum forms of calcium sulfate that may be contained therein. Calcination of gypsum to produce the hemihydrate form is carried out according to the following equation.
_{CaSO4.2H2O → CaSO4.0.5H2O + 1.5H2O}

Gypsum of Paris can react with water to form calcium sulfate dihydrate, which is a rigid product and is referred to herein as "set gypsum."

Gypsum may also be obtained synthetically as a by-product of industrial processes such as, for example, flue gas desulfurization from power plants (referred to in the art as "synzip"). Natural or synthetic gypsum can be calcined at high temperatures, typically greater than 150° C., thereby producing stucco (i.e., calcined gypsum in the form of calcium sulfate hemihydrate and/or calcium sulfate anhydrite). and the stucco may be subsequently rehydrated to form the set gypsum into a desired shape, such as a board.

Synthetic gypsum obtained from power plants is generally suitable for use in gypsum panels for construction projects. Synthetic gypsum is a byproduct of the flue gas desulfurization process from power plants (also known as desulfurized gypsum or desulfogypsum or DSG). In particular, flue gas containing sulfur dioxide is wet washed with lime or limestone, which in a subsequent reaction produces calcium sulfite.
CaCO ₃ +SO ₂ →CaSO ₃ +CO ₂
Calcium sulfite is then converted to calcium sulfate in the following reaction.
_CaSO3 + _{2H2O +} 1/ _2O2 → _CaSO4.2H2O
The hemihydrate form may then be produced by calcination in a manner similar to that used for natural gypsum.

However, many conventional coal-fired power plants are being shut down in favor of greener energy sources. Due to the closure of coal-fired power plants, there is a growing shortage of synthetic gypsum suitable for making gypsum panels. Low quality synthetic gypsum is available from power plants and other alternative sources, but gypsum from this alternative source often contains fairly high concentrations of extraneous salts, especially magnesium or sodium salts, especially magnesium chloride and sodium chloride. Minor amounts of potassium chloride and calcium chloride may also be present in synthetic gypsum from alternative sources. Extraneous salts can be a problem as they tend to reduce the adhesion between the board core and the coversheet, especially the backing paper coversheet.

This background description has been made by the inventors to assist the reader, and neither prior art citations nor indications of any of the problems presented are per se recognized in the art. It will be recognized that it is not. Although the principles described may, in some respects and embodiments, alleviate problems inherent in other systems, the scope of the protected innovations does not solve any particular problems described herein. It will be understood to be defined by the appended claims and not by the capabilities of the claimed invention.

The present invention provides a gypsum board and related methods and systems that exhibit improved adhesion between the gypsum layer of the board and the cover sheet. The invention is particularly applicable to boards formed from stucco with a high content of salt impurities. Generally, stucco is formed by firing gypsum from natural or synthetic sources. In nature, it is a common and abundant mineral that can be mined from the ground. A synthetic form of gypsum may be derived as a by-product from flue gas desulfurization (FGD) processes associated with coal-fired power plants burning high-sulfur coal. In power plants, sulfur dioxide emissions are removed by wet cleaning processes. Injection of limestone slurry precipitates synthetic gypsum after removal of fly ash. For example, some forms of synthetic gypsum contain a high content of salt impurities, which then remain in the stucco formed as gypsum of Paris. Salt impurities in synthetic gypsum can originate, for example, from high salt coal. These salt impurities have been found to adversely affect the bond between the cover sheet (eg, formed from paper) and the gypsum layer (eg, board core) within the board.

Accordingly, in one aspect, the present invention provides a gypsum board comprising a set gypsum core disposed between a front coversheet and a back coversheet. A set gypsum core is formed from a first slurry comprising water, stucco, and high salt impurity content, as well as optional ingredients discussed herein. The board includes at least one (ie, one, two, three, or four) of items (1)-(4) below. (1) At least one of the cover sheets, preferably at least the back cover sheet, is perforated. (2) At least one of the coversheets, preferably at least the back coversheet, is superabsorbent paper. (3) Starch is provided between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. (4) Skim-coated starch is provided. A board core prepared from the first slurry is positioned between the two cover sheets and has first and second faces. The board core can optionally contain board core starch. A back skim coat layer and a front skim coat layer are provided, each defining first and second skim coat surfaces. A skim coat is formed from each of the second and third slurries, which may be of the same or different composition. The second and third slurries include at least water and stucco. At least one of the second and third slurries contains skim-coated starch. The back skim coat layer is disposed in mating relation to the first core face, and the first face of the front skim coat layer is in mating relation to the second face of the board core. The second side of the back skim coat layer faces the back coversheet. The second side of the front skim coat layer faces the front coversheet. The skim-coat starch enhances the bond between the board core and the skim-coat prepared using the skim-coat starch, eg, the cover sheet preferably adjacent at least the back skim-coat layer.

In another aspect, the invention provides a method of making gypsum board. A stucco containing at least water and a high salt impurity content is mixed to form a first slurry. At least water and stucco are mixed to form second and third slurries which may be the same or different. A second slurry is applied in bonded relationship to the front coversheet to form a skim coat layer, the skim coat layer having a first side and a second side, the first side of the skim coat layer being , facing the front cover sheet. The first slurry is applied in bonded relationship to the skim coat layer to form a board core having a first side and a second side, the first side of the board core being the second side of the skim coat layer. Face to face. A back cover sheet is applied in bonded relationship to a second side of the board core side to form a board precursor. A third slurry comprising water, stucco, and skim coat starch is applied onto the first surface of the back cover sheet to form a second skim coat. When applied over the core, a second skim coat is placed between the second coversheet and the board core. The board precursor is dried in a kiln to form a board. The method further includes at least one (ie, one, two, three, four, or five) of items (1)-(5) below. (1) At least one of the cover sheets, preferably the back cover sheet, is perforated. (2) At least one of the coversheets, preferably the back coversheet, is superabsorbent paper. (3) Starch is applied such that it is disposed between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. (4) Skim-coated starch is included in the second and/or third slurries to strengthen the bond between the board core and the front and/or back cover sheets, respectively. (5) The drying process involves using a kiln containing at least one in-kiln high frequency moisture sensor therein. At least one burner, which can have burner power, can be used to provide heat in the kiln. A kiln moisture sensor is in communication with a controller outside the kiln and produces a kiln moisture reading. Drying measures the moisture content in the board upstream of the kiln using an upstream high frequency moisture sensor and an upstream sensor (e.g. microwave sensor) that is less affected by high salt concentrations in the slurry compared to the high frequency moisture sensor. Further comprising measuring the amount. The upstream sensor is in communication with the controller and produces a first upstream moisture reading and a second upstream moisture reading, respectively. Correlating the first and second moisture readings from the upstream moisture sensor. Bias the in-kiln high frequency moisture sensor to detect any error in the in-kiln moisture reading (indicated by the delta between the upstream sensor readings) if a delta exists between the first and second moisture readings. to correct). In some embodiments, drying measures the moisture content in the board downstream of the kiln using a downstream high frequency moisture sensor and a downstream sensor that is less susceptible to high salt concentrations in the slurry compared to the high frequency moisture sensor. Further comprising measuring the amount. A downstream high frequency sensor and other sensors that are not susceptible to high salt concentrations are in communication with the controller and generate a first downstream moisture reading and a second downstream moisture reading, respectively. Correlate downstream moisture readings. By adjusting (automatically or manually) the moisture setpoint and/or bias, the airflow and/or burner output changes in relation to any error generated by the high frequency sensor, ensuring a properly dried board. can bring.

In another aspect, the invention provides a method of making gypsum board. The method includes mixing at least water, stucco, and foam to form a first slurry. A first slurry is placed between a front coversheet and a back coversheet to form a board precursor. The board precursor is cut into segments. An in-kiln board containing therein at least one high-frequency in-kiln moisture sensor, the in-kiln moisture sensor being in communication with a controller outside the kiln to generate an in-kiln moisture reading. Moisture content in the board upstream of the kiln is evaluated using an upstream high frequency moisture sensor and an upstream sensor that is less susceptible to high salt concentrations in the slurry compared to high frequency moisture sensors. The upstream sensor is in communication with the controller and produces a first upstream moisture reading and a second upstream moisture reading, respectively. Moisture readings from upstream high frequency moisture sensors and upstream sensors that are less susceptible to high salt concentrations in the slurry are correlated compared to the high frequency moisture sensor. If a delta exists between the first and second moisture readings, the in-oven high frequency moisture sensor is biased to correct for any error in the in-oven moisture reading. In some embodiments, the method measures the moisture content in the board downstream of the kiln using a downstream high frequency moisture sensor and a downstream sensor that is less susceptible to high salt concentrations in the slurry compared to the high frequency moisture sensor. Further comprising measuring the amount. A downstream radio frequency sensor and other salt insensitive sensors are in communication with the controller and generate a first downstream moisture reading and a second downstream moisture reading, respectively. Moisture readings from downstream high frequency moisture sensors and downstream sensors that are less susceptible to high salt concentrations in the slurry than high frequency moisture sensors are correlated. The kiln is associated with burner firing rates and/or air flow modifiers to regulate the heating within the kiln. The burner firing rate and/or air extractor adjusts the temperature in the kiln when there is a delta between the moisture readings of the first downstream moisture sensor and the second downstream moisture sensor to used to reduce

In another aspect, the invention provides a method of drying a board precursor during board manufacture. The method includes providing a board precursor containing a core layer formed from stucco, water, and high salt impurity content. The board precursor is cut into segments. The segments are dried in a kiln containing at least one in-kiln high frequency moisture sensor therein. A kiln moisture sensor is in communication with a controller outside the kiln and produces a kiln moisture reading. The moisture content of the board precursor is measured upstream of the kiln using an upstream high frequency moisture sensor and an upstream sensor that is less susceptible to high salt concentrations in the slurry compared to the high frequency moisture sensor. The upstream sensor is in communication with the controller and produces a first upstream moisture reading and a second upstream moisture reading, respectively. Moisture readings from upstream high frequency moisture sensors and upstream sensors that are less susceptible to high salt concentrations in the slurry are correlated compared to the high frequency moisture sensor. If a delta exists between the first and second moisture readings, the in-oven high frequency moisture sensor is biased to correct for any error in the in-oven moisture reading. In some embodiments, the method measures the moisture content in the board downstream of the kiln using a downstream high frequency moisture sensor and a downstream sensor that is less susceptible to high salt concentrations in the slurry compared to the high frequency moisture sensor. Further comprising measuring the amount. A downstream radio frequency and high salt concentration insensitive sensor is in communication with the controller and produces a first downstream moisture reading and a second downstream moisture reading, respectively. Moisture readings from downstream high frequency moisture sensors and downstream sensors that are less susceptible to high salt concentrations in the slurry than high frequency moisture sensors are correlated. In some embodiments, burner power and/or air extraction devices associated with the kiln are provided. Burner power and/or air devices are used to adjust the temperature in the kiln to reduce heating therein if there is a discrepancy between the two downstream moisture readings.

In another aspect, the invention provides a system for drying board segments. The system includes a kiln containing at least one heat source and an in-kiln high frequency moisture sensor therein. A controller is provided outside the kiln. An upstream high frequency moisture sensor and an upstream sensor that is less susceptible to high salt concentrations in the slurry compared to high frequency moisture sensors are provided. An upstream radio frequency sensor and a microwave sensor are in communication with the controller and generate a first upstream moisture reading and a second upstream moisture reading, respectively. In some embodiments, the system further includes burner power and/or air extractors associated with the kiln. A setpoint and/or air extractor is in communication with the controller. In some embodiments, the system further includes a downstream high frequency moisture sensor and a downstream sensor that is less susceptible to high salt concentrations in the slurry compared to the high frequency moisture sensor. A downstream sensor is in communication with the controller and generates a first downstream moisture reading and a second downstream moisture reading, respectively. Burner power and/or air devices can be used to adjust the temperature within the kiln to reduce heating therein.

1 shows a cross-sectional view of a gypsum board of the present invention in which a board core layer (gypsum core) is sandwiched between a front coversheet and a back coversheet, the back coversheet including a plurality of holes therethrough. Figure 2 shows a plan view (axial view) of the gypsum board of Figure 1, allowing a better view of the array of holes in the back cover sheet; 1 shows a cross-sectional view of a gypsum board of the present invention in which a board core (gypsum core) is sandwiched between a front paper cover sheet and a back cover sheet, at least one of which is coated with a starch layer; FIG. . Figure 4 shows a plan view (axial view) of the gypsum board of Figure 3, allowing a better view of the array of holes in the back cover sheet; Figure 2 shows a perspective view of a gypsum board of the present invention attached to one side of a metal stud wall suitable in the wall system of the present invention; 1 is a schematic illustration of a cross-section of a wallboard having a skim coat according to an embodiment of the invention (not drawn to scale); FIG. 1 is a schematic illustration of a cross-section of a wallboard having a skim coat according to an embodiment of the invention (not drawn to scale); FIG. FIG. 4 is a schematic diagram of a line aspect showing a drying process according to embodiments of the present description; Figure 2 shows a perspective view of a gypsum board of the present invention attached to one side of a metal stud wall suitable for use in an exemplary wall system of the present invention; FIG. 2 shows a photograph of a back cover sheet with a plurality of through holes. FIG. Photographs demonstrating the effect of various salts on adhesion to the board core layer in 12 inch by 12 inch by 1/2 inch gypsum board with and without holes in the back cover sheet. show. Photographs demonstrating the effect of various salts on adhesion to the board core layer in 12 inch by 12 inch by 1/2 inch gypsum board with and without holes in the back cover sheet. show. Photographs demonstrating the effect of various salts on adhesion to the board core layer in 12 inch by 12 inch by 1/2 inch gypsum board with and without holes in the back cover sheet. show. To demonstrate the effect of perforation on a 12 inch by 12 inch by 1/2 inch gypsum board containing 30 ppm NaCl − Cl ⁻ from NaCl per million parts of calcium sulfate hemihydrate, the present invention with a perforated cover sheet Figure 1 shows a photograph comparing an inventive board to a board with an imperforate cover sheet. Figure 2 shows a photograph showing the effect of dilute starch solution on a 12" x 12" x 1/2" gypsum board containing 1200 ppm ^Cl- from _MgCl2 per million parts of calcium sulfate hemihydrate. FIG. 1 shows a photograph showing the effect of dilute starch solution on 12″×12″×1/2″ gypsum board containing 2100 ppm Cl ⁻ from MgCl ₂ per million parts of calcium sulfate hemihydrate. Figure 1 shows a photograph showing the effect of dilute starch solution and drilling on a 12" x 12" x 1/2" gypsum board containing 2000ppm of ^Cl- from NaCl per million parts of calcium sulfate hemihydrate. Figure 2 shows a photograph showing the effect of diluted starch solution on a 12 inch by 12 inch by 1/2 inch gypsum board containing 30 ppm of Cl ^{2 −} from NaCl per million parts of calcium sulfate hemihydrate. 3 is a photograph of two boards after bonding tests discussed in Example 3. FIG. 3 is a photograph of three boards after bonding tests discussed in Example 3. FIG. 3 is a photograph of three boards after bonding tests discussed in Example 3. FIG. 3 is a photograph of three boards after bonding tests discussed in Example 3. FIG. 3 is a photograph of three boards after bonding tests discussed in Example 4. FIG. 3 is a photograph of three boards after bonding tests discussed in Example 4. FIG. 4 is a graph of percent moisture (x-axis) versus actual percent moisture (y-axis), as discussed in Example 5. FIG. 4 is a graph of percent moisture (x-axis) versus actual percent moisture (y-axis), discussed in Example 5. FIG.

The present invention is based, at least in part, on enhancing adhesion between a gypsum layer and a cover sheet (eg, composed of paper). Gypsum board is formed to include a gypsum layer disposed between two cover sheets (a front cover sheet and a back cover sheet). The gypsum layer generally includes a core layer and a skim coat layer between the first major surface of the core and the coversheet. In some embodiments, there is a second skim coat layer between the second major surface of the core and the second cover sheet facing the first cover sheet, this arrangement being understood in the art. It is Embodiments of the present invention are particularly useful for gypsum boards in which the set gypsum layer is formed from a stucco slurry containing significant amounts of extraneous salts. For example, in some embodiments, the salt is a chloride salt, such as sodium chloride (NaCl), potassium chloride (KCl), magnesium chloride ( _MgCl2 ), and/or calcium chloride ( _CaCl2 ).

Such salts can be found, for example, in stucco slurries where the stucco is derived from low quality synthetic gypsum. In this regard, board manufacturing facilities are typically procured with gypsum, which is then calcined to form stucco. The stucco is then reacted with water to form a gypsum (ie, calcium sulfate dihydrate) layer of desired dimensions. It has been found that when low quality synthetic gypsum contains significant amounts of salt impurities, such salts remain in the stucco after calcination and are therefore present in the stucco slurry. In some embodiments, the stucco slurry is a high quality salt, e.g., at least about 150 ppm chloride anion per 1,000,000 parts by weight of the calcium sulfate hemihydrate, e.g. from about 150 ppm to about 2,000 ppm of chloride anion per 1,000,000 parts by weight of product. The presence of significant amounts of salt impurities has been found to interfere with adhesion between the gypsum layer and the cover sheet.

The gypsum layer of the board is prepared by mixing at least stucco, water, and optional additives as needed. A gypsum layer is sandwiched between a front coversheet and a back coversheet. One or more gypsum layers can form a primary gypsum layer in the form of a board core having two opposing major surfaces. A gypsum layer in the form of a thin skim coat can be placed on any major surface of the core. The sandwich structure is formed as a continuous ribbon at the wet end of the manufacturing line (near the main mixer). The continuous ribbon forms a board precursor, which is at least partially cured by the reaction of water and stucco as it is transported on a conveyor, cut into segments, and then dried in a kiln. The primary gypsum layer forms the board core, which is prepared from a first slurry, but the skim coat can be prepared from second and third slurries which can be the same or different from each other.

In order to enhance the coversheet-gypsum layer bond, the present invention uses a high content of salt impurities in the first slurry (and optionally the second and/or third slurry) , provides ingredients and techniques for enhancing bonding. Embodiments of the present invention employ at least one, preferably at least two of the following binding promotion items (1) to (5). (1) At least one of the cover sheets, preferably the back cover sheet, is perforated. (2) At least one of the coversheets, preferably the back coversheet, is superabsorbent paper. (3) Starch is applied between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. (4) skim-coated starch is included in the second and/or third slurries to strengthen the bond between the board core and the front and/or back cover sheets, respectively, wherein the skim-coated starch is added to the board; Strengthen the bond between the core and the front and/or back coversheet, respectively. (5) drying involves applying heat to a chamber (kiln) using an upstream high frequency moisture sensor and an upstream sensor that is less susceptible to high salt concentrations in the slurry compared to high frequency moisture sensors; measuring the moisture content in the board upstream of the The kiln contains therein at least one high frequency in-kiln moisture sensor, the in-kiln moisture sensor in communication with a controller outside the kiln to generate an in-kiln moisture reading. The upstream sensor is in communication with the controller and produces a first upstream moisture reading and a second upstream moisture reading, respectively. Moisture readings from upstream high frequency moisture sensors and upstream sensors that are less susceptible to high salt concentrations in the slurry than high frequency moisture sensors are correlated. If a delta exists between the first and second moisture readings, the in-oven high frequency moisture sensor is biased to correct for any error in the in-oven moisture reading. In some embodiments, the moisture content in the board downstream of the kiln is measured using a downstream high frequency moisture sensor and a downstream sensor that is less susceptible to high salt concentrations in the slurry compared to the high frequency moisture sensor. be done. A downstream sensor is in communication with the controller and generates a first downstream moisture reading and a second downstream moisture reading, respectively. Moisture readings from downstream high frequency moisture sensors and downstream sensors that are less susceptible to high salt concentrations in the slurry than high frequency moisture sensors are correlated. If there is a discrepancy between readings, burner power and/or air controls are used to adjust the temperature within the kiln (eg, to reduce the degree of heating therein). In some embodiments, three of items (1)-(5) are employed. In some embodiments, four of items (1)-(5) are employed. In some embodiments, all five of items (1)-(5) are employed. Related gypsum board products and other methods and systems are also provided.

The coversheet can be fibrous or non-fibrous. In some embodiments, they may be formed from paper, fiber mats, or other types of materials such as foils, plastics, glass mats, nonwoven materials such as blends of cellulose and inorganic fillers, and the like.

The front and back coversheets can have any suitable basis weight and thickness. Generally, the thickness of the front and back cover sheets (eg, composed of paper) is determined by the weight of the (eg, paper). For example, in some embodiments, the front and back coversheets are about 10 lb/msf to about 55 lb/msf, such as about 20 lb/msf to about 55 lb/msf, about 20 lb/msf to about 50 lb/msf, about 20 lb/msf /msf to about 40 lb/msf, about 30 lb/msf to about 55 lb/msf, about 30 lb/msf to about 50 lb/msf, about 30 lb/msf to about 40 lb/msf, and the like. However, in some embodiments, the presence of the intermediate sheet allows the use of lighter cover sheets, thereby reducing costs and/or allowing for lighter boards. For example, in some embodiments, one or both of the front and back coversheets are from about 15 lb/MSF to about 35 lb/msf, such as from about 20 lb/MSF to about 33 lb/msf, from about 20 lb/MSF to about 31 lb/msf. msf, from about 20 lb/MSF to about 29 lb/msf, from about 20 lb/MSF to about 27 lb/msf, from about 15 lb/MSF to about 31 lb/msf. A board of such weight should have a thickness of about 0.005 inch to about 0.015 inch, such as a nominal thickness of 0.007 to about 0.03 inch (eg, about 0.01 inch). can be done.

In some embodiments, the back cover sheet is perforated, as described in US patent application Ser. No. 16/401,675, incorporated herein by reference. Surprisingly, holes in the gypsum board back cover sheet may improve adhesion to board core layers containing large amounts of extraneous salts. The board core layer may be made from an aqueous slurry of stucco containing calcium sulfate hemihydrate and large amounts of extrinsic salts, particularly chloride salts. One or both of the coversheets may be paper coversheets which may be of the same or different paper material. Optionally, the front coversheet of the gypsum board may be perforated, which allows similar advantages. Further optionally, various additives may be present in the board core layer or the gypsum slurry used to form the board core layer. The board core layer may further include one or more high density regions (layers) in contact with and coated over the inner surface of the front or back coversheet. One or more high density regions may be in contact with the low density interior of the board core layer.

Without being bound by theory or mechanism, it is believed that the pores in the back cover sheet provide conduits for outward migration of chloride salts released from the board core layer or otherwise detrimentally agglomerates at the interface between the board core layer and the coversheet. Instead, if pores are present, chloride ions and their counterions (e.g., Na ⁺ , K ⁺ , Mg ²⁺ and/or Ca ²⁺ ) migrate at least partially through the pores, potentially May exit the board environment. Alternatively, the salt may precipitate in or just outside the pores on the outer surface of the back cover sheet. Salt precipitation on the outside of the pores reduces the "net salt" between the paper and the core, thus leaving less salt at the interface and resulting in better bonding between the paper and the core. In either case, improved adhesion between the board core layer and the coversheet may occur.

If the back cover sheet of the gypsum board is perforated in the manner described herein, the gypsum board will be more flexible than the same gypsum board but without perforations in the cover sheet. It may benefit from improved adhesion between sheets. Accordingly, the present invention provides a gypsum board containing a significant amount of extrinsic salts in the board core layer and a method for producing such a gypsum board using a gypsum source containing a significant amount of extrinsic salts. . Thus, at least one of the gypsum board cover sheets with a plurality of holes, particularly the holes in the back cover sheet, is exposed to a low quality gypsum source containing excess extraneous salts, especially chloride salts, forming the gypsum board. may be allowed to be used. Otherwise, such gypsum sources may be inadequate to form a gypsum board with sufficient adhesion between the board core layer and the coversheet. Advantageously, the present invention addresses this issue.

In some embodiments, the back and front coversheets are made from paper. However, the paper material of each coversheet may be the same or different. According to embodiments of the present invention, only the gypsum board back cover sheet contains a plurality of through holes. The back cover sheet is made from perforated paper.

Various grades of paper can be used for gypsum panels. For example, Manila grade paper with a smooth calendar finish is often used as the facer paper coversheet and Newsline paper with a rougher finish is often used as the backer paper coversheet. Typically both paper grades are multi-layer with at least one liner layer and multiple filler layers. However, if desired, at least one paper coversheet or both paper coversheets may be made from single ply paper.

As noted above, the back cover sheet can contain multiple holes in some embodiments. A plurality of holes may be arranged in the back cover sheet in any suitable manner. Typically, the holes are arranged in a pattern, such as a regular grid or array of holes (see, eg, FIG. 2). Other patterned arrangements of holes are also within the scope of this disclosure, and the particular arrangement of holes shown in FIG. 2 should not be considered limiting. An exemplary apparatus for perforating one or more cover sheets in gypsum board in a manner consistent with the present disclosure is described in US Patent Application Publication No. 2018/0065336, which is incorporated herein by reference in its entirety. It is

The holes in the cover sheet are present in a suitable shape, size and hole density to aid in drying and/or increased adhesion of the gypsum board.

Typically the holes have a substantially circular shape. However, it should be recognized that the holes may have alternative geometric shapes such as ovals, triangles, squares, rectangles, and the like. Any combination of circular and non-circular holes may be present, depending on the requirements of a particular application. Any combination of non-circular holes may be present.

Each hole in the cover sheet, particularly the back cover sheet, is sized in its largest lateral dimension from about 0.005 inch to about 0.1 inch, preferably from about 0.01 inch to about 0.1 inch, more preferably about An opening may be defined having a size ranging from 0.01 inches to about 0.02 inches. The term "maximum transverse dimension" refers to the maximum dimension measured across each hole in the plane of the coversheet. For circular holes, the maximum lateral dimension represents the diameter of the circular opening.

The holes in the back cover sheet are typically the same size and shape. However, the pores may be a mixture of pore sizes and/or shapes. The pore size, whether the same or different, may be within any of the ranges specified above. Further, if at least some of the holes have different shapes, there is a first plurality of holes having the first shape and first size and a second plurality of holes having different shapes and/or different sizes. sometimes. For example, the first plurality of holes and the second plurality of holes may have different shapes but substantially the same size.

Hole coverage density refers to the number of holes per unit area in the back cover sheet. The holes present in the back cover sheet are present at a suitable hole coverage density to promote effective board core layer adhesion. The hole density in the coversheet is from about 5 to about 50 holes/in ² , preferably from about 12 to about 25 holes/in ² , such as from about 10 to about 15 holes/in ² , or such as from about 15 to 20 holes/in 2 . /in ² . Typically, pores are about 0.1 to about 10%, more typically about 0.5 to about 5% of the surface of the back cover sheet.

In some embodiments, at least one of the coversheets (eg, the back coversheet) is conventionally coated, as described in US Patent Application No. 62/939,264, incorporated herein by reference. It is a super absorbent paper that absorbs more water than any other paper. When high salt stucco is used, the salt migrates to the surface of the paper coversheet, between the layers of the paper coversheet, and to the interface between the paper coversheet and the board core, resulting in poor adhesion and delamination. may occur. While not wishing to be bound by any particular theory, the use of super absorbent paper increases the amount of salt impurities that migrate to the outside of the cover paper and correspondingly the amount of salt that migrates to the interface of the cover sheet and core. is thought to reduce In addition, during the drying process in the kiln, when water evaporates from the surface of the board, super absorbent paper tends to absorb and evaporate water faster than conventional paper, resulting in more salt on the outside of the paper. is thought to move to

Superabsorbent paper can have any suitable weight and thickness. Generally, the weight of paper is determined by basis weight, which refers to the weight per unit area. This can be expressed as the weight of paper in pounds per thousand square feet. In some embodiments, the superabsorbent paper has a basis weight of from about 30 lb/MSF to about 70 lb/MSF, such as from about 42 lb/MSF to about 60 lb/MSF, such as from about 45 lb/MSF to about 55 lb/MSF. In some embodiments, the superabsorbent paper has a caliper of from about 7 mils to about 20 mils, such as from about 10 mils to about 15 mils (eg, about 12 mils). The water absorption of the surface over 60 seconds expressed in g/m ² is measured with the Cobb test. This test determines how many grams of water are absorbed on a 100 cm ² paper surface based on the Cobb test. The procedural standard for the Cobb test is described in TAPPI T 441.

Superabsorbent paper can have any suitable water absorbency higher than conventional paper. The bond side Cobb value refers to the inside of the paper in contact with the gypsum slurry and the liner side Cobb value refers to the outside of the paper not in contact with the slurry, these Cobb values are described in the TAPPI T 441 test procedure. Measured according to the TAPPI standard. For example, in some embodiments, the superabsorbent paper is at least about 1.8 g/100 cm ² , such as from about 1.8 g/100 cm ² to about 3 g/100 cm ² , such as from about 1.8 g/100 cm ² to about 2.9 g/100 cm ² , about 1.8 g/100 cm ² to about 2.7 g/100 cm ² , about 1.8 g/100 cm ² to about 2.5 g/100 cm ² , about 2 g/100 cm ² to about 3 g/100 cm ² , about 2 g/100 cm ² to about 2.9 g/100 cm ² , about 2 g/100 cm ² to about 2.7 g/100 cm ² , about 2 g/100 cm ² to about 2.5 g/100 cm ² , about 2.1 g/100 cm ² to about 3 g/100 cm ² , from about 2.1 g ^/ 100 cm ² to about 2.9 g/100 cm 2 , from about 2.1 g/100 cm ² to about 2.7 g/100 cm ² , from about 2.1 g/100 cm ² to about 2.1 g/100 cm 2 . 5 g/100 cm ² , from about 2.2 g/100 cm ² to about 3 g/100 cm ² , from about 2 g/100 cm ² to about 2.9 g/100 cm ^{2 , from about 2.2 g/100 cm 2 to} about 2.7 g/100 cm ² , or About 2.2 g/100 cm ² to about 2.5 g/100 cm ² , about 2.4 g/100 cm ² to about 3 g/100 cm ² , about 2.4 g/100 cm ² to about 2.9 g/100 cm ² , about 2.4 g /100 cm ² to about 2.7 g/100 cm ² .

In some embodiments, the superabsorbent paper is at least about 0.5 g/100 cm ² , such as from about 0.5 g/100 cm ² to about 1.5 g/100 cm ² , such as from about 0.5 g/100 cm ² to about 1.2 g/100 cm ² , about 0.7 g/100 cm ² to about 1.5 g/ ^{100 cm 2 , about 0.7 g/100 cm 2 to} about 1.2 g/100 cm ² , about 0.9 g/100 cm ² to about 1.5 g/100 cm 2 . 5 g/100 cm ² , such as from about 0.9 g/100 cm ² to about 1.2 g/100 cm ² . Examples of superabsorbent papers include Newsline Hi-Abs and News SHW HiAbs from USG. Newsline Hi Abs have a basis weight of about 45 lb/MSF to about 48 lb/MSF. Newsline SHW Hi Abs is a super absorbent paper and has a basis weight of from about 53 to about 63.5 lb/MSF.

In some embodiments, a starch layer is disposed on the inner surface of the coversheet, as described in US patent application Ser. No. 16/401,719, incorporated herein by reference. Surprisingly, the presence of a starch layer can improve adhesion to board cores made from aqueous slurries of stucco containing calcium sulfate hemihydrate and large amounts of extraneous salts. Preferably, the starch layer is a continuous starch layer disposed over the entire inner surface of the back coversheet. Optionally, another starch layer is also placed over the inner surface of the front coversheet. One or both of the cover sheets may be paper cover sheets which may be of the same or different paper material. Optionally, additional starch and/or other additives may be present in the board core or aqueous gypsum slurry used to form the board core.

The board core may include less dense regions (layers) and one or more higher density layers in contact with the inner surface of the front or back paper cover sheet or starch layer coated thereon. may contain regions (layers) of

Thus, a starch layer coated on at least one of the cover sheets may allow a low quality gypsum source containing excess extraneous salts to be used to form the gypsum board.

Preferably, the board may include a front skim coat and/or a back skim coat. In preferred embodiments, the skim coat layer is generally denser and much thinner than the set gypsum core. In some embodiments, the layers forming the set gypsum core cumulatively contribute the most to the thickness of the gypsum layers and to the overall board. In some embodiments, the set gypsum core comprises a substantial thickness (e.g., at least about 90%, at least about 92%, at least about 95%, or at least about 97%) of the total thickness of all gypsum layers. Configure. In some embodiments, the front and/or back skim coat layers have a dry thickness of about 0.125 inch (1/8 inch) to about 0.016 inch (1/64 inch). In preferred embodiments, at least one skim coat layer has a thickness of about 0.08 inch to about 0.02 inch, such as about 0.08 inch to about 0.03 inch, about 0.07 inch to about 0.02 inch, about 0.07 inch to about 0.03 inch, about 0.06 inch to about 0.02 inch, about 0.06 inch to about 0.03 inch, about 0.05 inch to about 0.02 inch, about 0 0.05 inch to about 0.03 inch, about 0.04 inch to about 0.02 inch, or about 0.04 inch to about 0.03 inch.

In some embodiments, one or both skim coats are It can be prepared from a slurry containing skim-coated starch. Surprisingly and unexpectedly, it has been found that the inclusion of skim coat starch in the very thin back ski coat further strengthens the bond between the core and the back cover sheet. While not wishing to be bound by any particular theory, it is believed that the presence of skim coat starch in the thin skim coat acts as an adhesive that firmly bonds the paper fibers to the gypsum crystals within the core. Therefore, it is effective in strengthening the bond between the cover sheet and the gypsum core.

In a preferred embodiment, the starch is native starch and is included in the skim coat layer between the board core and the backing paper coversheet. In this way, the present invention provides for the use of undesired extraneous salts, including, for example, chloride salts such as NaCl, KCl, MgCl ₂ , and/or CaCl ₂ that have been previously found to interfere with paper-core bonding. Allows for improved adhesion even when the board core and/or other gypsum layers are formed from stucco derived from low quality synthetic gypsum containing

Thus, in some embodiments, the primary slurry used to form the gypsum board core can contain core starch, while the back skim coat layer and optionally the top skim coat layer are skimmed. It is formed from a slurry containing coated starch. In some embodiments, the skim coat starch is provided at a higher relative concentration in the slurry for forming the skim coat layer compared to the amount of core starch in the slurry for forming the board core. As discussed herein, skim-coated starch surprisingly and unexpectedly enhances adhesion of its corresponding (adjacent) coversheets, even in the presence of undesirable salt impurities. In some embodiments, core starch is not believed to be effective in aiding cover sheet adhesion when salt impurities are present.

Core starches are discussed, for example, in U.S. Pat. As such, it is provided to enhance strength. In some embodiments, migratory starches known in the art can additionally be included in the core slurry. Migratory starches usually have smaller chain lengths (eg, due to acid or enzymatic denaturation) and migrate to the core-coversheet interface to further strengthen the bond without significantly affecting the strength of the core.

In preferred embodiments, the core starch is in the form of pregelatinized starch, for example, a viscosity of from about 20 centipoise to about 700 (e.g., from about 20 centipoise to about 300 centipoise) when the starch is subjected to conditions according to the VMA method. or from about 30 centipoise to about 200 centipoise). In some embodiments, the core starch is native starch. In some embodiments, the core starch has (i) a hydrothermal viscosity of from about 20 BU to about 300 BU by hydrothermal viscosity assay (HWVA method) and/or (ii) water at a starch concentration of 15% solids. The starch was placed in a slurry containing the , with a moderate peak viscosity of about 120 BU to 1000 BU when viscosity was measured by using a Viscograph-E instrument set at 75 rpm and 700 cmg. In some embodiments, the core starch comprises migratory starch having a molecular weight of about 6,000 Daltons or less.

In some embodiments, skim coat starch is included in at least one skim coat layer (and optionally in some embodiments both skim coat layers). The starch used in making the skim coat layer enhances the bond between the core and its adjacent cover sheet compared to boards made without the starch in the slurry for forming the skim coat layer. effective for In preferred embodiments, the starch is native starch. In some embodiments, the skim-coated starch has (i) a hydrothermal viscosity of about 20 BU to about 300 BU by hydrothermal viscosity assay (HWVA method) and/or (ii) a starch concentration of 15% solids in water. and the starch is heated from 25°C to 95°C at a rate of 3°C/min, the slurry is held at 95°C for 10 minutes, and the starch is heated to 50°C at a rate of -3°C/min. It contains uncooked starch with a medium peak viscosity of about 120 BU to 1000 BU when viscosity is measured by using a Viscograph-E instrument set at 75 rpm and 700 cmg, cooled. Alternatively, if desired, the skim-coated starch can be in the form of a pregelatinized starch, e.g., from about 20 centipoise to about 700 (e.g., , from about 20 centipoise to about 300 centipoise, or from about 30 centipoise to about 200 centipoise). In some embodiments, skim-coated starch comprises migratory starch having a molecular weight of about 6,000 Daltons or less. HWVA methods are described, for example, in U.S. Patent Publication No. 2019/0023612A1, while VMA methods are described, for example, in U.S. Patent Publication No. 2012/0113124, and these methodologies include: incorporated herein by reference.

In some embodiments, the skim-coated starch is in the second and/or third slurries from about 0.3% to about 8.0% by weight of the stucco, such as from about 1.0% to about 1.0% by weight of the stucco. It is present in at least one of the skim coat layers, preferably at least the skim coat layer adjacent to the backing paper, in an amount of about 4.0% by weight. In some embodiments, the skim-coat starch is included in the second skim-coat layer adjacent to the back coversheet, while the slurry for making the first skim-coat layer adjacent to the front coversheet includes, for example, the core It is formed from the same slurry for making the core, which contains starch. The total skim coat starch usage in the second and/or third slurry is greater than the core starch usage in the first slurry. In a preferred embodiment, the amount of core starch used is from about 0.1% to about 1.5% by weight of stucco, while the amount of skim coat starch is used from about 1.5% to about 1.5% by weight of stucco. 4.0% by weight. In some embodiments, the core starch is a pregelatinized starch, the skim-coated starch is an uncooked starch, and a migratory starch is additionally optional in the core starch and/or the skim-coated starch.

FIG. 1 shows a gypsum core (board core layer) 12 (e.g., 0.5 inch thick) with a backer paper cover sheet (back cover sheet) 14 and a facer paper cover, each of which may be single-ply or multi-ply paper. 1 shows a cross-sectional embodiment of a wallboard panel (gypsum board) 10 of the present invention sandwiched between a sheet (front cover sheet) 18. FIG. A backer paper cover sheet (back cover sheet) 14 has holes 20 therein. The inner surface of the backer paper cover sheet 14 forms the bonding side 24 of the backer paper cover sheet 14 that faces the gypsum core 12 . The inner surface of the facer paper coversheet 18 forms a bonding side 28 facing the gypsum core 12 . The exterior surface of the backer paper cover sheet 14 faces the wall framing of the room after the wallboard panel 10 has been installed as an interior wall. After the wallboard panel 10 has been installed as an interior wall, the exterior surface of the facer paper cover sheet 18 faces the interior of the room.

A backer paper cover sheet (back cover sheet) 14 includes a plurality of through holes 20 in accordance with the present invention. FIG. 2 shows a plan (axial) view of the wallboard panel 10 and an exemplary configuration of holes 20 in the backer paper cover sheet 14 may be seen. As shown, holes 20 are patterned in a regular array of columns and rows. It should be appreciated that other patterned arrangements of holes 20 are also within the scope of the present invention, and that the depicted number, spacing, and coverage density of holes 20 should not be considered limiting. .

The holes 20 in the backer paper coversheet 14 surprisingly improve bonding performance between the gypsum core 12 and the backer paper coversheet 14 . Improved bonding performance may be particularly evident when the gypsum used to form the gypsum core 12 has a high salt concentration.

An optional thin dense gypsum layer (low density region) 22 exists between the gypsum core 12 and the facer paper coversheet 18 and contacts the gypsum core 12 and the facer paper coversheet 18 . Thus, a thin dense gypsum layer 22 is interposed between the gypsum core 12 and the facer paper coversheet 18 . Another optional thin dense gypsum layer (not shown) may be interposed between the gypsum core 12 and the backer paper coversheet 14 to contact the gypsum core 12 and the backer paper coversheet 14. . Generally, the gypsum core 12 and thin dense gypsum layer 22 have the same composition and are adjacent to each other. Collectively, the gypsum core 12 and the thin dense gypsum layer 22 may define the interior of the gypsum board 10, the gypsum core 12 being the low density region or layer and the thin dense gypsum layer. 22 is a relatively high density region or layer. Typically, the aqueous gypsum slurry used to form gypsum core 12 is foamed. Accordingly, the low density regions may be formed from a gypsum slurry in a foamed state. In contrast, the aqueous gypsum slurry used to form the thin, dense gypsum layer 22 is not foamed. Accordingly, the high density regions may be formed from unfoamed gypsum slurry. Accordingly, the thin, dense gypsum layer 22 is relatively denser than the rest of the gypsum core 12 .

Thus, high density regions may have lower porosity associated therewith than low density regions. Typically, a thin dense gypsum layer 22 is applied to the inner surface of the selected coversheet. If present, a thin dense gypsum layer 22 is interposed between the coversheet and the low density region (gypsum core 12).

Certain amounts of one or more chloride salts may be present in the gypsum core 12 according to the present disclosure. If a high density region (thin, dense gypsum layer 22) is included, one or more chloride salts may also be present therein. Generally, the one or more chloride salts may be selected from the group consisting of NaCl, KCl, _MgCl2 , _CaCl2 and any combination thereof.

The concentration of chloride anions in the aqueous slurry used to fabricate the board core 12 and, if present, the high density region (the thin, dense gypsum layer 22) is 1,000,000 parts by weight of calcium sulfate. about 500 ppm to about 3000 ppm per hemihydrate, typically about 500 ppm to about 2000 ppm, more typically about 500 ppm to about 1500 ppm per 1,000,000 parts by weight of calcium sulfate hemihydrate can range from

Due to the passage of salt through the pores, some of the salt from the original aqueous gypsum slurry may not remain in the core 12 and, if present, in the high density regions (thin, dense gypsum layer 22). may be present in the pores of the holes or outside the paper sheet.

FIG. 3 shows a gypsum core 112 (e.g., about 0.5 inch thick) with a backer paper cover sheet (back cover sheet) 114 and a facer paper cover sheet (front cover), each of which may be single-ply or multi-ply paper. 116 shows the wallboard panel 110 of an embodiment of the present invention sandwiched between a sheet 116; The inner surface of the backer paper cover sheet 114 forms the bonding side 124 of the backer paper cover sheet 114 that faces the gypsum core. The inner surface of the facer paper coversheet 116 forms a bonding side 126 facing the gypsum core 112 . The outer surface of the backer paper cover sheet 114 faces the wall framing of the room (see FIG. 5) after the wallboard panel 110 has been installed as the inner wall. After installing the wallboard panel 110 as an interior wall, the exterior surface of the facer paper cover sheet 116 faces the interior of the room.

A starch layer 120 is present on the bonding side 124 of the backer sheet 114 . An optional starch layer 120 is present on the bonding side 126 of the facer paper coversheet 116 . An optional thin dense gypsum layer 122 lies between the gypsum core 112 and the facer paper coversheet 116 and contacts the gypsum core 112 and the facer paper coversheet 116 . If a thin dense gypsum layer 122 is present, the starch layer 120 is between the thin dense gypsum layer 122 and the facer paper coversheet 116 . Another optional thin dense gypsum layer (not shown) may be present between the gypsum core 112 and the backer paper coversheet 114 . Generally, gypsum core 112 and thin dense gypsum layer 122 have the same composition and are adjacent to each other. However, the core slurry (aqueous slurry) used to form the gypsum core 112 is foamed and the aqueous slurry used to form the thin dense gypsum layer 122 is not foamed. Therefore, the thin, dense gypsum layer slurry is denser than the core slurry.

Starch layer 120 surprisingly improves bonding performance between gypsum core 112 and backer sheet 114 . The improved bonding performance is especially noticeable when the gypsum has a high salt concentration.

The starch layer is disposed on the backing paper in an amount ranging from about 0.5 to 15 lbs/MSF, preferably from about 0.5 to 5 lbs/MSF, more preferably from about 1 to 2 lbs/MSF (MSF=1000 square feet). be. Starch is used as a binder and can be native (uncooked) starch, pregelatinized starch, or a combination of native and pregelatinized starch.

Generally, the relatively low density interior region (gypsum core 112) and the relatively high density region (thin, dense gypsum layer 122) have the same composition and are adjacent to each other. However, the low density interior regions may be formed from a foamed gypsum slurry, while the high density regions are formed from an unfoamed gypsum slurry such that a denser layer is formed. Sometimes. That is, a high density region may have a lower porosity associated therewith than a low density interior region. Typically, a thin dense gypsum layer 122 is applied to the inner surface of the selected coversheet. If a high density region is also present on the selected coversheet, the starch layer 120 is between the coversheet and the high density region (thin, dense gypsum layer 122).

One or more chloride salts may be present in board core 112 of the present disclosure. One or more chloride salts may also be present in dense regions (thin, dense gypsum layer 122) if included. Generally, the one or more chloride salts include any chloride salts from the stucco or other ingredients used to make the aqueous slurry for making the board.

The concentration of chloride anions in the aqueous slurry used to make the board core 112 and, if present, the high density region (the thin, dense gypsum layer 122) is 1,000,000 parts by weight of calcium sulfate. It may range from about 500 ppm to about 3000 ppm, typically from about 1000 ppm to about 3000 ppm, more typically from about 2000 ppm to about 3000 ppm, per hemihydrate.

For illustrative purposes, Figures 6A and 6B schematically depict an embodiment of the invention in which a composite gypsum board 210 is shown. Board 210 includes a front coversheet 212 and a back coversheet 214 . The front coversheet 212 has a first side 216 and a second side 218, which is generally the surface that the board 210 is viewed upon installation. The back cover sheet 214 has a first side 220 and a second side 222, which is generally the outer side of the board 210 that faces inwardly at the studs, joists, etc. when installed.

The back skim coat layer 224 has a first side 226 and a second side 228 facing the first side 220 of the back cover sheet 214 . A board core 230 is positioned between the two cover sheets 212 and 214 . Generally, the skim coat layer is a relatively denser and thinner layer of gypsum than the board core 230 . Board core 230 has a first side 232 and a second side 234 . First side 232 of board core 230 faces first side 220 of back cover sheet 214 . Back skim coat layer 224 includes skim coat starch 235 (shown as dots in FIGS. 6A and 6B) to enhance adhesion of core 230 to cover sheet 214 . A front skim coat layer 236 is preferably provided between the front coversheet 212 and the board core 230, as shown in FIGS. 6A and 6B.

If included, the front skim coat layer 236 has a first surface 238 facing the board core 230 and a second surface 240 facing the front coversheet 212, as seen in FIGS. 6A and 6B. When the front skim coat layer 236 is present, in some embodiments it is used to form the board core, such as, for example, containing core starch and no skim coat starch, as shown in FIG. 6A. Formed from the same slurry used. Alternatively, surface skim-coat layer 236 is formed from a slurry containing skim-coat starch 235 in some embodiments, as seen in FIG. 6B.

In a wall assembly, the board can be attached to a substrate, typically studs in a framing structure. In the wall assembly, the back surface of the board (i.e., the outer surface of the back cover sheet) faces inward toward the studs, whereas the front surface of the board (i.e., the front side) faces the board in a hanging state when installed in use. The outer surface of the cover sheet) is visible. FIG. 5 is a perspective view of a typical building wall system 530 that can be used in the wall system of the present invention. FIG. 5 shows a stud wall “skeleton” 532 that includes a plurality of studs 534 , upper tracks 536 and lower tracks 538 . Gypsum board 510 may be secured to one or both sides of studs 534 in any known manner to close the wall and form the interior face or surface of the wall or ceiling.

The stucco slurry used to make the set gypsum layer of the board includes stucco in the form of, for example, calcium sulfate alpha-hemihydrate, calcium sulfate beta-hemihydrate, and/or calcium sulfate anhydrous. In addition to the stucco, water and core starch, the stucco slurry may contain commonly known optional additives such as foaming agents, polyphosphates, dispersants, accelerators, retarders, and the like. The board core is preferably formed from an agent that contributes to its low density, preferably a blowing agent, although in some embodiments low density fillers (e.g. perlite, low density aggregate, etc.) can be used. can be done. Various blowing agent regimes are well known in the art. Blowing agents may be included to form a distribution of cells within the crystalline matrix of the set gypsum. In some embodiments, the blowing agent comprises a major weight portion of the unstable component and a minor weight portion of the stable component (eg, when the unstable and stable/unstable blends are combined). The weight ratio of the unstable component to the stable component is effective to create a cell distribution within the set gypsum core. See, for example, US Pat. Nos. 5,643,510, 6,342,284, and 6,632,550. In some embodiments, the effervescent agent comprises an alkyl sulfate surfactant.

Many commercially known foaming agents are available and can be used in accordance with embodiments of the present disclosure, such as the HYONIC line of soap products (eg, 25AS) from GEO Specialty Chemicals (Ambler, PA). Other commercially available soaps include Polystep B25 from Stepan Company, Northfield, Illinois. The blowing agents described herein may be used alone or in combination with other blowing agents. The foam can be pre-formed and then added to the stucco slurry. Pre-generation can occur by injecting air into the aqueous blowing agent. Methods and apparatus for generating foam are well known. See, for example, U.S. Pat. Nos. 4,518,652, 2,080,009, and 2,017,022.

In some embodiments, the blowing agent comprises, consists of, or consists essentially of at least one alkyl sulfate, at least one alkyl ether sulfate, or any combination thereof, but essentially It does not contain olefins (eg olefin sulfates) and/or alkynes. Essentially free of olefins or alkynes means that the blowing agent is (i) 0% by weight based on the weight of the stucco, or free of olefins and/or alkynes, or (ii) an ineffective amount, or (iii) It is meant to contain insignificant amounts of either olefins and/or alkynes. An example of an ineffective amount is an amount below the threshold amount to achieve the intended purpose of using the olefinic and/or alkyne blowing agent, as will be understood by those skilled in the art. An insignificant amount, as understood by those skilled in the art, is, for example, less than about 0.001 weight percent, such as less than about 0.0005 weight percent, less than about 0.001 weight percent, about 0.001 weight percent, based on the weight of the stucco. It may be less than 00001% by weight or the like.

Some types of labile soaps are alkyl sulfate surfactants with different chain lengths and different cations according to embodiments of the present disclosure. Suitable chain lengths may be, for example, C ₈ -C ₁₂ , eg C ₈ -C ₁₀ , or C ₁₀ -C ₁₂ . Suitable cations include, for example, sodium, ammonium, magnesium, or potassium. Examples of unstable soaps include, for example, sodium dodecyl sulfate, magnesium dodecyl sulfate, sodium decyl sulfate, ammonium dodecyl sulfate, potassium dodecyl sulfate, potassium decyl sulfate, sodium octyl sulfate, magnesium decyl sulfate, ammonium decyl sulfate, blends thereof, and Any combination thereof is included.

Some types of stable soaps, according to embodiments of the present disclosure, are alkoxylated (eg, ethoxylated) alkyl sulfate surfactants with different (generally longer) chain lengths and different cations. Suitable chain lengths may be, for example, C ₁₀ -C ₁₄ , eg C ₁₂ -C ₁₄ , or C ₁₀ -C ₁₂ . Suitable cations include, for example, sodium, ammonium, magnesium, or potassium. Examples of stable soaps include, for example, sodium laureth sulfate, potassium laureth sulfate, magnesium laureth sulfate, ammonium laureth sulfate, blends thereof, and any combination thereof. In some embodiments, any combination of stable and unstable soaps from these lists can be used.

Examples of combinations of blowing agents and their additions in the preparation of foamed gypsum products are disclosed in US Pat. No. 5,643,510, incorporated herein by reference. For example, a first blowing agent that forms a stable foam and a second blowing agent that forms an unstable foam can be combined. In some embodiments, the first blowing agent is a soap, such as an alkoxyl having an alkyl chain length of 8-12 carbon atoms and an alkoxy (eg, ethoxy) group chain length of 1-4 units. Alkyl sulfate soap. The second blowing agent is optionally non-alkoxylated (eg, non-ethoxylated) with an alkyl chain length of 6-20 carbon atoms, such as 6-18 or 6-16 carbon atoms. Alkyl sulfate soap. Adjusting the individual amounts of these two soaps allows control of the board foam structure until about 100% stable soap or about 100% unstable soap is achieved, according to some embodiments. It is believed that

In some embodiments, the fatty alcohol is: Optionally, a blowing agent may be included, for example, in the premix to prepare the foam. This provides better control over the size and distribution of the bubble (air) voids by providing improved foam stability. The fatty alcohol may be any suitable fatty alcohol. "Aliphatic," as defined throughout this specification, refers to alkyl, alkenyl, or alkynyl, which may be substituted or unsubstituted, branched or unbranched, and saturated or unsaturated; In connection with the embodiments, it will be understood to be represented by carbon chains described herein, eg, C _x -C _y , where x and y are integers. The term aliphatic therefore also refers to chains that have heteroatom substitutions that maintain the hydrophobicity of the group. A fatty alcohol may be a single compound or a combination of two or more compounds. In some embodiments, the optional fatty alcohol is a _C6 - _C20 fatty alcohol (eg, _C6 - _C18 , _C6 - _C116 , _C6 - _C14 , _C6 - _C12 , _C6 C ₁₀ , C ₆ -C ₈ , C ₈ -C ₁₆ , C ₈ -C ₁₄ , C ₈ -C ₁₂ , C ₈ -C ₁₀ , C ₁₀ -C 16 , C ₁₀ -C ₁₄ , C _{10 -C 12} , C ₁₂ -C ₁₆ , C ₁₂ -C ₁₄ , or C ₁₄ -C ₁₆ fatty alcohols). Examples include octanol, nonanol, decanol, undecanol, dodecanol, or any combination thereof.

In some embodiments, the optional suds stabilizer comprises a fatty alcohol and is essentially free of fatty acid alkyloamides or carboxylic acid taurides. In some embodiments, the optional foam stabilizer is essentially free of glycols, although glycols are included in some embodiments, for example, to allow for higher surfactant content. can be Essentially free of any of the above ingredients means that the foam stabilizer is (i) 0% by weight based on the weight of any of these ingredients, or (ii) an ineffective amount, or (iii) an insignificant amount of any of these ingredients; An example of an ineffective amount is an amount below the threshold amount for achieving the intended purpose of using any of these ingredients, as one skilled in the art would appreciate. An insignificant amount, as understood by those skilled in the art, is, for example, less than about 0.0001% by weight, such as less than about 0.00005% by weight, less than about 0.00001% by weight, about 0 It may be less than .000001 weight percent, and so on.

It has been found that a suitable void distribution and wall thickness (independently) can be effective in enhancing strength, especially in lower density boards (eg, less than about 35 pcf). See for example US2007/0048490 and US2008/0090068. Evaporated water voids, generally having voids of about 5 μm diameter or less, also contribute to the total void distribution along with the air (bubble) voids previously described. In some embodiments, the volume ratio of voids having pore sizes greater than about 5 microns to voids having pore sizes less than or equal to about 5 microns is from about 0.5:1 to about 9:1, such as about 0.7 : 1 to about 9:1, about 0.8:1 to about 9:1, about 1.4:1 to about 9:1, about 1.8:1 to about 9:1, about 2.3:1 to about 9:1, about 0.7:1 to about 6:1, about 1.4:1 to about 6:1, about 1.8:1 to about 6:1, about 0.7:1 to about 4:1, about 1.4:1 to about 4:1, about 1.8:1 to about 4:1, about 0.5:1 to about 2.3:1, about 0.7:1 to about 2.3:1, from about 0.8:1 to about 2.3:1, from about 1.4:1 to about 2.3:1, from about 1.8:1 to about 2.3:1, etc. .

As used herein, void size is calculated from the largest diameter of an individual void within the core. The maximum diameter is the same as the ferret diameter. The maximum diameter of each of the defined voids can be obtained from the image of the sample. The images can be taken using any suitable technique, such as scanning electron microscopy (SEM), which provides two-dimensional images. The pore size of bulk voids can be measured in SEM images so that the randomness of the cross-section (pores) of the voids can provide an average diameter. This calculation can be improved by taking measurements of voids in multiple images randomly located throughout the core of the sample. In addition, building a three-dimensional solid model of the core based on several two-dimensional SEM images can also improve void size calculations. Another technique is X-ray CT scan analysis (XMT), which provides three-dimensional images. Another technique is optical microscopy, where light contrast can be used, for example, to help determine void depth. Void can be measured either manually or by using image analysis software such as ImageJ developed by NIH. Those skilled in the art will appreciate that manual determination of void size and distribution from images can be determined by visual observation of the dimensions of each void. Samples can be obtained by dividing the gypsum board.

Blowing agents can be included in the stucco slurry in any suitable amount, depending, for example, on the desired density. A solution of blowing agent is prepared, for example, at about 0.5% (w/w). A suitable amount of air is mixed with a suitable amount of blowing agent solution and added to the slurry. Depending on the amount of air required, the concentration of the blowing agent solution can vary from about 0.1% to about 1% (w/w). Because the skim coat layer has a higher density, the slurry for forming the skim coat layer can be made with less (or no) foam.

Fatty alcohols, if included, may be present in the stucco slurry in any suitable amount. In some embodiments, the fatty alcohol is from about 0.0001% to about 0.03% by weight of the stucco, such as from about 0.0001% to about 0.025% by weight of the stucco, from about 0.001% to about 0.025% by weight of the stucco. 0001% to about 0.02% by weight of the stucco, or from about 0.0001% to about 0.01% by weight of the stucco. Since the slurry for the skim coat layer contains little or no foam, the fatty alcohol is not required in the skim coat layer, or in lesser amounts, such as from about 0.0001% to about 0.004% by weight of the stucco, For example, from about 0.00001% to about 0.003% by weight of stucco, from about 0.00001% to about 0.0015% by weight of stucco, or from about 0.00001% to about 0.001% by weight of stucco. can be included in

In some embodiments, it has been found that chloride salts can act as accelerators, thus increasing the amount of retarder used. _{Second ,} magnesium, calcium _, Or the aluminum cation is chelated by the retarder, resulting in consumption of the retarder. Therefore, more retardant is required from divalent or trivalent salts than from monovalent salts.

In some embodiments, the stucco slurry optionally contains boric acid. Surprisingly and unexpectedly, the presence of boric acid is associated with the presence of boric acid between the gypsum layer and at least one cover sheet, even when the gypsum layer is made from stucco containing a high content of salt impurities. Bonds can be strengthened. While not wishing to be bound by any particular theory, it is believed that the addition of boric acid prevents over-calcination of the surface gypsum within the kiln. It is also believed to reduce mold formation caused by high salt concentrations on the surface of the board. In some embodiments, boric acid is present in an amount from about 0.01% to about 0.5% by weight of the stucco. In some embodiments, boric acid can be present in an amount from about 0.01% to about 0.3%, or from about 0.05% to about 0.3%, by weight of the stucco.

Other ingredients known in the art may also be included in the board core slurry including, for example, accelerators, retarders, and the like. Accelerators can be in various forms (eg, wet gypsum accelerators, heat resistance accelerators, and climate stabilization accelerators). See, for example, US Pat. Nos. 3,573,947 and 6,409,825. In some embodiments that include accelerators and/or retarders, the accelerators and/or retarders each comprise about 0% to about 10% by weight of the stucco (e.g., about 0.1% to about 10% ), etc., may be present in the stucco slurry in amounts of, for example, about 0% to about 5% by weight of stucco (eg, about 0.1% to about 5%) on a solids basis.

Additionally, in some embodiments, the gypsum layer can be further formed from at least one dispersant to enhance flowability. Dispersants may be included in the stucco slurry in dry form with other dry ingredients and/or in liquid form with other liquid ingredients. Examples of dispersants include naphthalene sulfonates, such as polynaphthalene sulfonic acid and its salts (polynaphthalene sulfonates) and derivatives, which are condensation products of naphthalene sulfonic acid and formaldehyde; and polycarboxylate dispersants, such as polycarboxylic acid ethers. , such as PCE211, PCE111, 1641, 1641F, or PCE 2641 type dispersants, such as MELFLUX 2641F, MELFLUX 2651F, MELFLUX 1641F, MELFLUX 2500L dispersants (BASF), and Coatex, Inc. and/or lignosulfonate or sulfonated lignin. Lignosulfonates are water-soluble anionic polyelectrolyte polymers that are by-products of wood pulp production using sulfite pulping. One example of lignin useful in practicing the principles of embodiments of the present disclosure is Reed Lignin Inc. and Marasperse C-21 available from Epson.

Low molecular weight dispersants are generally preferred. In the case of naphthalene sulfonate dispersants, in some embodiments they are selected to have a molecular weight of from about 3,000 to about 10,000 (eg, from about 8,000 to about 10,000). In some embodiments, for example, higher water demand naphthalene sulfonates with molecular weights greater than 10,000 can be used. As another example, for PCE211 type dispersants, in some embodiments, the molecular weight can be from about 20,000 to about 60,000, which is slower than dispersants with molecular weights greater than 60,000. Less is.

An example of a naphthalene sulfonate is DILOFLO available from GEO Specialty Chemicals. DILOFLO is a 45% aqueous solution of naphthalene sulfonate, although other aqueous solutions are also readily available, eg, ranging from about 35% to about 55% solids by weight. Naphthalene sulfonate can be used in dry solid or powder form, for example LOMAR D available from GEO Specialty Chemicals. Another example of a naphthalene sulfonate is DAXAD available from GEO Specialty Chemicals (Ambler, PA).

Dispersants, if included, may be provided in any suitable amount. In some embodiments, for example, the dispersant is present in the stucco slurry, for example, from about 0% to about 0.5% by weight of the stucco, such as from about 0.01% to about 0.7%, For example, it can be present in amounts of about 0.01% to about 0.4%, about 0.1% to about 0.2%, and the like.

In some embodiments, the gypsum layer can optionally be further formed from at least one phosphate-containing compound to enhance green strength, dimensional stability, and/or flex resistance. For example, phosphate-containing components useful in some embodiments include water-soluble components, which may be in the form of ions, salts, or acids, i.e., condensed phosphoric acids, each of which Contains two or more phosphate units, salts or ions of condensed phosphates, each of which contains two or more phosphate units, monobasic salts or monovalent ions of orthophosphates, and water-soluble acyclic polyphosphate salts . See, for example, US Pat. Nos. 6,342,284, 6,632,550, 6,815,049, and 6,822,033.

When added in some embodiments, phosphate compositions can enhance green strength, resistance to permanent deformation (eg, deflection), dimensional stability, and the like. Green strength refers to the strength of the board while still wet during manufacture. Due to the rigors of the manufacturing process, board precursors can be damaged in the manufacturing line without sufficient green strength.

For example, trimetaphosphate compounds including sodium trimetaphosphate, potassium trimetaphosphate, lithium trimetaphosphate, and ammonium trimetaphosphate can be used. Sodium trimetaphosphate (STMP) is preferred, but other phosphates may be suitable, such as sodium tetrametaphosphate, having from about 6 to about 27 repeating phosphate units and having the molecular formula Na _n+2 P _n O _3n+1 (formula in, n=6-27), tetrapotassium pyrophosphate with the molecular formula K ₄ P ₂ O ₇ , dipotassium trisodium tripolyphosphate with the molecular formula Na ₃ K ₂ P ₃ O ₁₀ , the molecular formula Na ₅ P Sodium _{tripolyphosphate} with _the molecular formula _Na4P2O7 , Tetrasodium pyrophosphate with the molecular formula _{Na4P2O7 ,} Aluminum trimetaphosphate with the molecular formula Al( _PO3 ) ₃ , Acidic _{pyrophosphate with the} molecular formula _Na2H2P2O7 sodium, ammonium polyphosphate having 1,000 to 3,000 repeating phosphate units and having the molecular formula (NH ₄ ) _n+2 P _n O _3n+1 , where n=1,000 to 3,000, or 2 or more repeating phosphate units and having the molecular formula Hn _{+ 2PnO3n +1} , where n is 2 or greater.

Polyphosphate, if included, can be present in any suitable amount. Illustratively, in some embodiments, the polyphosphate is, for example, about 0.1% to about 1% of the stucco, such as about 0.2% to about 0.4% by weight of the stucco, about 0% of the stucco. It may be present in the slurry in an amount from to about 0.5%, such as from about 0% to about 0.2% by weight. Accordingly, the dispersant and polyphosphate may optionally be in any suitable amount in the stucco slurry.

If desired, in some embodiments, components for fire resistance and/or water resistance can also optionally be included in the gypsum slurry. Examples include, for example, siloxane (water resistant), fibers, aluminum trihydrite (ATH), heat sink additives such as magnesium hydroxide, and/or high expansion particles (e.g., when heated at 1560° F. for about 1 hour, expandable to about 300% or more of its original volume). Further disclosure regarding such additives can be found in US Pat. No. 8,323,785. High expansion vermiculite may be included, but other refractory materials may be included. When present, fire or water resistant additives can be included in any suitable amount as needed depending, for example, on fire rating and similar performance parameters. For example, when included, the fire or water resistant additive is from about 0.5% to about 10%, such as from about 1% to about 10%, from about 1% to about 8%, by weight of the stucco. , from about 2% to about 10%, from about 2% to about 8% by weight, and the like. If included, the siloxane may desirably be introduced in the form of an emulsion. The slurry can then be molded and dried under conditions that promote polymerization of the siloxanes to form a highly crosslinked silicone resin. A catalyst can be added to the gypsum slurry that promotes the polymerization of siloxane to form a highly crosslinked silicone resin. A solventless methylhydrogen siloxane fluid can be used as the siloxane. This product is a siloxane fluid that does not contain water or solvents. Based on the weight of dry ingredients, it is believed that from about 0.3% to about 1.0% siloxane may be used if desired. For example, from about 0.4% to about 0.8% siloxane may be present in the gypsum slurry, based on dry stucco weight, if desired. Any one or more of these components may be absent for fire resistance and/or water resistance. For example, siloxane may not be present.

In such refractory embodiments, clay is preferably included in the stucco slurry. The presence of clay in refractory boards prepared with high levels of chloride is believed to significantly reduce heat shrinkage in the event of a fire. Any suitable clay can be used, such as kaolin clay. In some embodiments, clay is present in an amount from about 1% to about 10% by weight of the stucco. In some embodiments, clay can be present in an amount from about 1% to about 5% by weight of the stucco.

The board core has a desired total composite board density, such as from about 16 pcf (about 260 kg/m ³ ) to about 40 pcf, such as from about 18 pcf to about 40 pcf, 18 pcf to about 38 pcf, 18 pcf to about 36 pcf, 18 pcf to about 32 pcf, 20 pcf. contributing to a core density of from to about 40 pcf, from 20 pcf to about 36 pcf, from 20 pcf to about 32 pcf, from 22 pcf to about 40 pcf, from 22 pcf to about 36 pcf, from 22 pcf to about 32 pcf, from 26 pcf to about 40 pcf, from 26 pcf to about 36 pcf, or from 26 pcf to about 32 pcf can have any suitable density useful for In some embodiments, ^the board core has ^an even lower density, e.g. and so on. For example, in some embodiments, the core density is about 12 pcf (about 190 kg/m ³ ) to about 30 pcf, about 14 pcf (about 220 kg/m ³ ) to about 30 pcf, 16 pcf to about 30 pcf, 16 pcf to about 28 pcf, 16 pcf to about 26 pcf, 16 pcf to about 22 pcf (about 350 kg/m ³ ), 18 pcf to about 30 pcf, 18 pcf to about 28 pcf, 18 pcf to about 26 pcf, 18 pcf to about 24 pcf, 20 pcf to about 30 pcf, 20 pcf to about 28 pcf, 20 pcf to about 26 pcf , 20 pcf to about 24 pcf, 22 pcf to about 28 pcf, and the like.

In some embodiments, composite boards made according to the present disclosure meet testing protocols according to ASTM Standard C473-10. For example, in some embodiments, when the board is cast at 1/2 inch thickness, the dry board has at least about 67 lb _f (pound force) as determined according to ASTM C473-10 (Method B) , e.g., at least about 68 lb _f , at least about 70 lb _f , at least about 72 lb f , at least about 74 lb _f , at least about 75 lb _f , at least about 76 lb _f , at least about 77 lb _{f ,} etc. In various embodiments, the nail pull resistance is about 67 lb _f to about 100 lb _f , about 67 lb _f to about 95 lb _f , about 67 lb _f to about 90 lb _f , about 67 lb _f to about 85 lb _f , about 67 lb _f to about 80 lb _{f .} about 67 lb _f to about 75 lb _f , about 68 lb _f to about 100 lb _f , about 68 lb _f to about 95 lb _f , about 68 lb _f to about 90 lb _f , about 68 lb _f to about 85 lb _f , about 68 lb _f to about 80 lb _f , 70 lb _f to about 100 lb _f , about 70 lb _f to about 95 lb _f , about 70 lb _f to about 90 lb _f , about 70 lb _f to about 85 lb _f , about 70 lb _f to about 80 lb _f , about 72 lb _f to about 100 lb _f , about 72 lb _f to about 95 lb _f , about 72 lb _f to about 90 lb _f , about 72 lb _f to about 85 lb _f , about 72 lb _f to about 80 lb _f , about 72 lb _f to about 77 lb _f , about 72 lb _f to about 75 lb _f , about 75 lb _f to about 100 lb _f , about 75 lb _f to about 95 lb _f , about 75 lb _f to about 90 lb _f , about 75 lb _f to about 85 lb _f , about 75 lb _f to about 80 lb _f , about 75 lb _f to about 77 lb _f , about 77 lb _f to about 100 lb _f , about 77 lb _f to about 95 lb _f , about 77 lb _f to about 90 lb _f , about 77 lb _f to about 85 lb _f , or about 77 lb _f to about 80 lb _f .

In some embodiments, the composite gypsum board has at least about 11 lb _f , such as at least about 12 lb _f , at least about 13 lb _f , at least about 14 lb f , at least about 14 lb _f , as determined according to ASTM C473-10, Method B. It can have an average core hardness of 15 lb _f , at least about 16 lb _f , at least about 17 lb _f , at least about 18 lb _f , at least about 19 lb _f , at least about 20 lb _f , at least about 21 lb _f , or at least about 22 lb _f . In some embodiments, the board is about 11 lb _f to about 25 lb _f , such as about 11 lb _f to about 22 lb _f , about 11 lb _f to about 21 lb _f , about 11 lb _f to about 20 lb _f , about 11 lb _f to about 19 lb f . _f , about 11 lb _f to about 18 lb _f , about 11 lb _f to about 17 lb _f , about 11 lb _f to about 16 lb _f , about 11 lb _f to about 15 lb _f , about 11 lb _f to about 14 lb _f , about 11 lb _f to about 13 lb _f , about 11 lb _f to about 12 lb _f , about 12 lb _f to about 25 lb _f , about 12 lb _f to about 22 lb _f , about 12 lb _f to about 21 lb _f , about 12 lb _f to about 20 lb _f , about 12 lb _f to about 19 lb f , about 12 lb _{f f} to about 18 lb _f , about 12 lb _f to about 17 lb _f , about 12 lb _f to about 16 lb f , about 12 lb _f to about 15 lb _f , about 12 lb _f to about 14 lb _f , about 12 lb _f to about 13 lb _f , about 13 lb _{f to} about 25 lb _f , about 13 lb _f to about 22 lb _f , about 13 lb _f to about 21 lb _f , about 13 lb _f to about 20 lb _f , about 13 lb _f to about 19 lb _f , about 13 lb _f to about 18 lb _f , about 13 lb _f to about 17 lb f _f , about 13 lb _f to about 16 lb _f , about 13 lb _f to about 15 lb _f , about 13 lb _f to about 14 lb _f , about 14 lb _f to about 25 lb _f , about 14 lb _f to about 22 lb _f , about 14 lb _f to about 21 lb _f , about 14 lb _f to about 20 lb _f , about 14 lb _f to about 19 lb _f , about 14 lb _f to about 18 lb _f , about 14 lb _f to about 17 lb f , about 14 lb _f to about 16 lb _f , about 14 lb _f to about 15 lb _f , about 15 lb _{f f} to about 25 lb _f , about 15 lb _f to about 22 lb _f , about 15 lb _f to about 21 lb _f , about 15 lb _f to about 20 lb _f , about 15 lb _f to about 19 lb _f , about 15 lb _f to about 18 lb _f , about 15 lb _f to about 17 lb _f , about 15 lb _f to about 16 lb _f , about 16 lb _f to about 25 lb _f , about 16 lb _f to about 22 lb _f , about 16 lb _f to about 21 lb _f , about 16 lb _f to about 20 lb _f , about 16 lb _f to about 19 lb _f , about 16 _{lb f} to about 18 lb _f , about 16 lb _f to about 17 lb f , about 17 lb _f to about 25 lb _f , about 17 lb _f to about 22 lb _f , about 17 lb _f to about 21 lb _f , about 17 lb _f to about 20 lb _f , about 17 lb _f to about 19 lb _f , about 17 lb _f to about 18 lb _f , about 18 lb _f to about 25 lb _f , about 18 lb _f to about 22 lb _f , about 18 lb _f to about 21 lb _f , about 18 lb _f to about 20 lb _f , about 18 lb _f to about 19 lb _f , about 19 lb _f to about 25 lb _f , about 19 lb _f to about 22 lb _f , about 19 lb _f to about 21 lb _f , about 19 lb _f to about 20 lb _f , about 21 lb _f to about 25 lb _f , about It can have a core hardness of from 21 lb _f to about 22 lb _f , or from about 22 lb _f to about 25 lb _f .

With respect to flexural strength, in some embodiments, when cast into 1/2 inch thick board, the dry board is at least about 36 lb _f in the machine direction as determined according to ASTM Standard C473-10 (e.g. , at least about 38 lb _f , such as at least about 40 lb _f ), and/or a flexural strength across the width of at least about 107 lb _f (eg, at least about 110 lb _f , at least about 112 lb _f , etc.). In various embodiments, the board is about 36 lb _f to about 60 lb _f , such as about 36 lb _f to about 55 lb _f , about 36 lb _f to about 50 lb _f , about 36 lb _f to about 45 lb _f , about 36 lb _f to about 40 lb _f , about 36 lb _f to about 38 lb _f , about 38 lb _f to about 60 lb _f , about 38 lb _f to about 55 lb _f , about 38 lb _f to about 50 lb _f , about 38 lb _f to about 45 lb _f , about 38 lb _f to about 40 lb _f , about It can have a machine direction bending strength of 40 lb _f to about 60 lb _f , about 40 lb _f to about 55 lb _f , about 40 lb _f to about 50 lb _f , or about 40 lb _f to about 45 lb _f . In various embodiments, the board is about 107 lb _f to about 130 lb _f , such as about 107 lb _f to about 125 lb _f , about 107 lb _f to about 120 lb _f , about 107 lb _f to about 115 lb f , about 107 lb _{f to} about 112 lb _f , about 107 lb _f to about 110 lb _f , about 110 _{lb f} to about 130 lb _f , about 110 lb _f to about 125 lb f , about 110 lb _f to about 120 lb _f , about 110 lb _f to about 115 lb _f , about 110 lb _f to about 112 lb _f , about It can have a transverse flexural strength of 112 lb _f to about 130 lb _f , about 112 lb _f to about 125 lb _f , about 112 lb _f to about 120 lb _f , or about 112 lb _f to about 115 lb _f .

Advantageously, in various embodiments at various board densities described herein, the dry composite gypsum board is at least about 170 psi (1,170 kPa), such as from about 170 psi to about 1,000 psi (6, 900 kPa), from about 170 psi to about 900 psi (6,200 kPa), from about 170 psi to about 800 psi (5,500 kPa), from about 170 psi to about 700 psi (4,800 kPa), from about 170 psi to about 600 psi (4,100 kPa), from about 170 psi about 500 psi (3,450 kPa), about 170 psi to about 450 psi (3,100 kPa), about 170 psi to about 400 psi (2,760 kPa), about 170 psi to about 350 psi (2,410 kPa), about 170 psi to about 300 psi (2,070 kPa) ), or from about 170 psi to about 250 psi (1,720 kPa). In some embodiments, the board is at least about 450 psi (3,100 kPa), at least about 500 psi (3,450 kPa), at least about 550 psi (3,800 kPa), at least about 600 psi (4,100 kPa), at least about 650 psi ( 4,500 kPa), at least about 700 psi (4,800 kPa), at least about 750 psi (5,200 kPa), at least about 800 psi (5,500 kPa), at least about 850 psi (5,850 kPa), at least about 900 psi (6,200 kPa), It has a compressive strength of at least about 950 psi (6,550 kPa), or at least about 1,000 psi (6,900 kPa). Further, in some embodiments, compressive strength may be limited by any two of the aforementioned points. For example, the compressive strength can be between about 450 psi and about 1,000 psi (eg, between about 500 psi and about 900 psi, between about 600 psi and about 800 psi, etc.). As used herein, compressive strength is measured using a materials testing system commercially available as ATS Machine Model 1610 from Applied Test Systems (Butler, Pa.). The load is applied continuously without impact at a rate of 1 inch/minute.

A gypsum board according to embodiments of the present invention may be made on a typical gypsum wallboard manufacturing line. For example, board manufacturing techniques are described, for example, in US Patent No. 7,364,676, US Patent Application Publication No. 2010/0247937, and US Patent Application No. 16/581,070. Briefly, the process typically involves releasing the coversheet onto a moving conveyor. This cover sheet is the "face" cover sheet in such an embodiment because gypsum board is usually formed "face down". Front and/or back skim coats, as known in the art, can optionally be included.

In some embodiments, one or both skim coat layers have an average dry core hardness that is at least about 1.5 times greater than the average dry core hardness of the board core, wherein the average core hardness is ASTM C-473-07 for example, at least about 2 times greater, 2.5 times greater, 3 times greater, 3.5 times greater, 4 times greater, 4.5 times greater, etc., each of these ranges being, for example, It can have any mathematically appropriate upper bound, such as 8, 7, 6, 5, 4, 3, or 2.

The slurry for forming the board core and for forming the skim coat layer can be formed by any suitable method. For example, one mixer can be used to develop both slurry streams. The mixer can, for example, optionally be in the form of a "pin mixer" or "pinless mixer" in which the raw materials are agitated. Alternatively, two or more separate mixers can be used. Multiple mixers can be in series or not connected. Examples of mixers are described in EP 1637302 (B1), EP 2929996 (B1), EP 3342571 (A1), and US Patent Application 2017/0008192 (A1). . As required for efficiency, the mixer used for the skim coat layer is: Some embodiments may have less mixing volume capacity. The "main" mixer (i.e., for forming the board core slurry) comprises a body and a discharge conduit (e.g., gate-canister-boot arrangement known in the art or US Pat. No. 6,494,609 and a modified exit design (MOD) arrangement described in US Pat. No. 6,874,930). A foaming agent and/or core starch may be added in the mixer's discharge conduit (eg, in the gate as described in US Pat. Nos. 5,683,635 and 6,494,609).

In embodiments where skim-coated starch is used, in a two-mixer system, the appropriate starch can be adjusted in each mixer. Any suitable arrangement may be used when a single mixer is used. For example, the skim coat stream can exit through ports and outlets in the body of the mixer, ie upstream of the discharge conduit. The skim coat outlet is provided with one or more inlets to allow the introduction of skim coat starch and any other desired ingredients different from the board core slurry exiting the mixer's discharge conduit. If the blowing agent is inserted into the discharge conduit, the amount of blowing agent is removed upstream of where it is added and thus reduced or avoided in the skim coat stream, thereby reducing the skim coat layer as needed. allows to increase the density of If a blowing agent is present in the skim coat stream, it can be counteracted by techniques known in the art. In a preferred embodiment, the back skim coat layer is formed from a skim coat stream. If desired, a top skim coat layer can also be formed from the skim coat stream. However, in some embodiments, the front skim coat layer can be formed from a slurry stream exiting the discharge conduit, which stream is also used to form the board core. To increase the density of the front skim coat layer relative to the board core, any bubbles therein can be eliminated if desired.

In some embodiments, the discharge conduit is, for example, US Patent Application Publication No. 2012/0168527 A1 (Application No. 13/341,016) and US Patent Application Publication No. 2012/0170403 A1 (Application 13/341,209) may include a slurry distributor having either a single feed port or multiple feed ports. In those embodiments, by using a slurry distributor with multiple inlets, the discharge conduit may include a suitable flow divider, such as those described in US Patent Application Publication No. 2012/0170403A1.

As is understood in the art, boards are typically formed in a sandwich construction simultaneously and sequentially. The front coversheet moves as a continuous ribbon on a moving conveyor. After exiting the mixer, the front skim coat layer slurry is applied to the (eg, moving) front coversheet. Also, a hard edge known in the art can optionally be formed from the same slurry stream that forms the skim coat layers (eg, front and/or back skim coat layers), for example, for convenience.

A board core slurry is then applied over the skim coat layer and covered by a second coversheet (typically the "back" coversheet) to provide a wet assembly in the form of a sandwich structure that is the final product board precursor. to form The back (bottom) cover sheet may optionally contain skim-coated starch as described herein to enhance the bond between the backing paper and the board core. can support The back skim coat layer can be formed from the same or different gypsum slurry as the front skim coat layer. In some embodiments, a skim coat layer is applied to the back side of the board, i.e., to the bottom (back) coversheet in bonding relationship, but no skim coat layer is applied between the core and the top coversheet.

The back cover sheet (paper backing facer sheet) may be perforated before the back cover sheet contacts the gypsum slurry. The back cover sheet may be procured/obtained from the manufacturer with holes already present, or the holes may be introduced just prior to contacting the back cover sheet with the gypsum slurry. As such, the pores do not extend into the board core layer or gypsum slurry prior to setting. For example, the plurality of holes may be introduced using a suitable wallboard drilling apparatus, such as that described in US Patent Application Publication No. 2018/0065336. However, it should be appreciated that any suitable wallboard punching device may be used.

In some embodiments, a starch layer is present on at least one coversheet, particularly the back coversheet, to increase adhesion thereto. A starch layer may be pre-coated on the inner surface of at least one of the front paper cover sheet and the back cover sheet. Alternatively, the method may further comprise applying a starch layer to the inner surface of at least one of the front paper coversheet and the back coversheet. Starch, as defined above, may be applied to the inner surface as a continuous starch layer. More specifically, the starch is added to the front paper cover sheet and the /or may be applied to the inner surface of the backing paper coversheet. Suitable methods for applying the starch layer to either the backing paper coversheet or the front paper coversheet include, for example, spraying, painting, inkjet printing, stenciling, stencil printing, roller coating, dip coating (immersion), and the like. Sometimes.

In some embodiments, the cover (facing down at the wet end of the board machine) is folded at the edges of the board so that the edge of the paper meets the backing paper (facing up at the wet end of the board machine). Since it can be folded over to form a board envelope, it can be manufactured to be slightly wider than the width of the final board product. For example, for a nominal 48 inch wide board, the cover can have a width of about 50 inches or more (eg, about 50 to about 52 inches, eg, about 50.375 inches). Correspondingly, in some embodiments, the backing paper may be manufactured to be narrower than the width of the board. Thus, for a nominal 48 inch wide board, the backing paper can have a width of less than about 48 inches (eg, about 46.5 inches to about 47.5 inches, eg, about 47.125 inches).

The wetting assembly thereby provided includes a forming station where the product is sized (e.g., via a forming plate) to the desired thickness, and one or more knife sections where it is cut to the desired length. carried to The wet assembly is allowed to set to form an interlocking crystalline matrix of set gypsum, and excess water is removed using a drying process (eg, by transporting the assembly through a kiln).

It is also common to use vibration in the manufacture of gypsum board to remove large voids or air pockets from the deposited slurry. Each of the above steps, as well as processes and equipment for performing such steps, are known in the art.

It has been found that the presence of high levels of salt impurities in the stucco slurry can complicate the drying process. After the ribbon of board precursor has been substantially cured, as described herein, it is cut into segments and dried in a kiln. The kiln is typically equipped with one or more moisture sensors, which are in communication with a programmable logic controller to produce moisture readings (eg, moisture percentage). The moisture value is then used to adjust the degree of heating in the kiln, either automatically via a programmable logic controller, for example, or manually by a boardline operator. However, it has been found that high concentrations of salt impurities in stucco can cause the sensor to produce false moisture readings, which are usually higher than the true moisture values. This can overheat the board (eg, due to excessive time and/or temperature in the kiln).

Excessive drying of the board can lead to board quality problems such as cracking and can further exacerbate poor bonding between the board's primary gypsum layer and one or both of the cover sheets. If the board is heated too much, some of the set gypsum may undesirably calcine and reform calcium sulfate hemihydrate adjacent to one or both coversheets, causing the coversheets to separate from the primary gypsum layer. may separate. It is therefore difficult to achieve a good bond between the coversheet and the gypsum layer in the presence of salt impurities, but excessive heating of the board when removing excess water can alleviate this difficulty. make worse.

In some embodiments, additional moisture sensors are provided upstream and/or downstream of the kiln to compensate for and adjust for the presence of salt impurities in the stucco slurry. The sensors are in communication with a programmable logic controller (often referred to in the art as a PLC). Moisture values between two upstream sensors and/or moisture values between two downstream sensors can be correlated to determine if there is a delta between either or both sets of readings. If delta is found, the heating inside the kiln can be adjusted manually or automatically by the controller to avoid overdrying. Thus, the drying process according to some embodiments of the present invention allows determining whether there is a high salt content in the board precursor that interferes with the moisture reading of the in-kiln sensor, and , to allow adjustment of the drying to correct for any error caused by salt content.

For example, FIG. 7 schematically illustrates one embodiment of a suitable arrangement. Manufacturing line 700 contains a mixer 705 at the wet end of the line. After the stucco slurries of the board core and skim coat layers are each placed between the cover sheets to form a continuous ribbon of board precursor, the ribbon travels down the line on conveyor 710 and is cut into segments by, for example, a knife. disconnected.

Kiln 715 contains a desired number of drying zones with one or more heat sources, such as burners, therein. Two drying zones 720 and 725 are represented in FIG. Alternatively, however, kiln 715 may contain one zone, or three or more zones as desired (eg, up to 24-36 or more zones as desired). Each zone can be individually adjusted to the desired heating environment as needed. Kiln 715 contains two kiln moisture sensors 730 and 735 both located within zone 725 . Kiln moisture sensors 730 and 735 are selected to withstand the harsh heating environment within kiln 715 . For example, kiln moisture sensors 730 and 735 are durable enough to handle the heated environment in kiln 715, but if high salt concentrations are present in the stucco slurry used to make the gypsum layer. Additionally, it can be in the form of a high frequency sensor that is susceptible to erroneous moisture readings.

An upstream high frequency moisture sensor 740 and an upstream sensor 745 that is less susceptible to high salinity (compared to high frequency sensors) are positioned to measure the moisture content of the cut ribbon just prior to entering the kiln 715 . ing. A downstream high frequency moisture sensor 750 and a downstream sensor 755 that is not susceptible to high salinity are optionally provided and positioned to measure the moisture content of the cut ribbon immediately after passing through the kiln 715. there is Each sensor 730, 735, 740, 745, 750, and 755 is in communication with a programmable logic controller 760, which can include known memory hardware as required. Signals can be sent back and forth between controller 760 and sensors 730 , 735 , 740 , 745 , 750 , and 755 . Controller 760 is also used to make adjustments with various controls within the kiln, for example, to regulate the heat for the drying process.

The inventors have found that the in-kiln high frequency moisture sensors 730 and 735 can be affected by the salt impurity content associated with the stucco, which can result in inaccurate moisture readings. I found out. For example, sensors 730 and 735 may inaccurately identify more moisture than is actually present, thereby leading to excessive dryness and reduced quality of the board caused by the manufacturing process, as well as poor, imperfections. lead to an increased incidence of defective or failing boards. Upstream sensors 740 and 745 and/or downstream sensors 750 and 755 work with controller 760 to adjust the heating in kiln 715 to adjust for erroneous moisture readings from in-kiln high frequency sensors 730 and 735 . arranged to do.

The upstream high frequency sensor 740, if present, can also be affected by the high salt content associated with stucco, while other upstream sensors are chosen to be less susceptible to salt. Accordingly, the respective moisture readings generated by upstream sensors 740 and 745 can be correlated, eg, manually or by controller 760, to determine if there is any delta between them. can. If the values are correlated without any discrepancies, this indicates a negligible content of salt impurities in the board and no adjustment is required. In this case, heating in the kiln 715 can proceed using the raw values of moisture produced by the in-kiln sensors 730 and 735 .

However, if there is a delta between the moisture values produced by upstream sensors 740 and 745, it indicates that salt impurities are present and the moisture value produced by high frequency sensor 740 can be compromised and its As a result, the in-kiln RF sensors 730 and 735 will be inaccurate. To compensate, controller 760 can be used to bias the moisture values generated by sensors 730 and 735, thereby adjusting the heating control regime in communication with controller 760 to the correct heating parameters, Improper drying (eg, over-drying) can be avoided.

Similarly, the moisture readings produced by downstream sensors 750 and 755 are also correlated. If there are no discrepancies between the respective temperature readings, no adjustment is required. However, if there is a difference between the moisture readings, thereby indicating corruption of the moisture values due to high salt content, adjustments to the heating regime in communication with the controller 760 can be made. In this regard, kiln 715 has airflow controls 765 and burner outputs 770 that can be varied to regulate the internal temperature of one or more zones of kiln 715 . Burner power 770, for example, uses a scale of 0 to 100, where 100 is maximum burner power and 0 indicates off. Output 770 drives burners to alter fuel and combustion air to increase or decrease heat.

For example, if there is a delta in the moisture readings generated by the downstream sensors 750 and 755, the controller 760 or human line operator may extract more hot air from the kiln thereby lowering the drying temperature and/or The heat in the kiln 715 can be reduced by lowering the temperature set point. Therefore, if present, both downstream sensors 750 and 755 send moisture readings to controller 760, which can calculate if there is a difference. If desired, the controller 760 can change the moisture setpoint accordingly. Changing the moisture setpoint can change the temperature in the kiln 715 by changing either the air extraction or the burner power. These calculations and adjustments can also be performed manually in some embodiments.

A high frequency moisture sensor can produce a dielectric reading. Such sensors can be made to withstand the temperatures within the kiln 715 . Suitable high frequency sensors are commercially available, for example, from Sensortech Systems, Oxnard, CA. Sensors that are less susceptible to high salt content (eg, associated with stucco) can be in forms such as microwave or X-ray technology. These types of sensors may not be able to withstand the rigors of the heating environment within the kiln. A preferred sensor that is less sensitive to salt content is a microwave sensor. While not wishing to be bound by any particular theory, it is believed that microwave-based sensors measure vibrations of water molecules and are less susceptible to being damaged by the presence of high levels of salt. Microwave-based sensors are commercially available, for example, from TEWS, Hamburg, Germany.

The invention is further described by the following illustrative clauses. However, the invention is not limited to the following clauses.

Clause 1. A gypsum board, a method of making a gypsum board, a method of drying a board, or a system for drying a board as described herein.

Clause 2. a board core layer comprising set gypsum; a front paper cover sheet having an exterior surface and an interior surface, the interior surface contacting the first surface of the board core layer; and a back paper cover sheet having an exterior surface and an interior surface. a gypsum board including a backing paper coversheet, the inner surface of which contacts the second side of the board core layer, the board core layer being disposed between the front paper coversheet and the backing paper coversheet. a backing perforated paper cover sheet comprising a plurality of through holes, a board core layer resulting from curing of an aqueous slurry comprising water and stucco between the first cover sheet and the second cover sheet, the stucco; comprises calcium sulfate hemihydrate, and the aqueous slurry contains at least 60 weight percent of said calcium sulfate hemihydrate on a dry basis, about 500 ppm per 1,000,000 parts by weight of said calcium sulfate hemihydrate A gypsum board comprising from to about 3000 ppm chloride anions and a water to calcium sulfate hemihydrate weight ratio of 0.2:1 to 1.2:1.

Article 3. 3. The gypsum board of clause 2, wherein the front cover sheet is a front paper cover sheet and the back cover sheet is a back paper cover sheet.

Article 4. A gypsum board according to clause 2 or 3, wherein the plurality of holes are arranged in a pattern.

Article 5. A gypsum board according to any one of clauses 2-4, wherein the plurality of perforations has a substantially circular shape.

Clause 6. The gypsum board of any one of clauses 2-5, wherein each hole defines an opening ranging in size from about 0.005 inch to about 0.1 inch.

Article 7. The gypsum board of any one of clauses 2-6, wherein each hole defines an opening ranging in size from about 0.01 inch to about 0.02 inch.

Article 8. The gypsum board of any one of clauses 2-7, wherein the back cover sheet has a hole coverage density ranging from about 5 holes/in ² to about 50 holes/in ² .

Article 9. The gypsum board of any one of clauses 2-8, wherein the back cover sheet has a hole coverage density ranging from about 12 holes/in ² to about 25 holes/in ² .

Clause 10. wherein the board core layer comprises a low density region and at least one high density region, wherein the at least one high density region is interposed as a layer between the low density region and the front or back coversheet. The gypsum board according to any one of 2 to 9.

Clause 11. The low density area is between a first high density area disposed as a first layer contacting the front coversheet and a second high density area disposed as a second layer contacting the back coversheet. 11. A gypsum board according to clause 10, sandwiched between

Clause 12. 11. The gypsum board of clause 10, wherein the low density region is formed from a foamed gypsum slurry and includes a plurality of voids therein.

Article 13. Clause 2-12, wherein the set gypsum is formed from synthetic gypsum comprising one or more chloride salts, said chloride salts providing at least a portion of said chloride anions. The gypsum board described in .

Article 14. 14. The gypsum board of clause 13, wherein the aqueous slurry has from about 1000 ppm to about 3000 ppm of said chloride anion per 1,000,000 parts by weight of said calcium sulfate hemihydrate.

Article 15. a board core layer comprising set gypsum, a front paper cover sheet having an exterior surface and an interior surface, the interior surface contacting the first surface of the board core; and a back paper cover sheet having an exterior surface and an interior surface. a gypsum board including a backing paper cover sheet, the inner surface contacting the second side of the board core, wherein the inner surface of at least one of the front paper cover sheet and the backing paper cover sheet is coated with a starch layer and a core layer is between the first cover sheet and the second cover sheet, the core layer being between the front paper cover sheet and the back cover sheet; resulting from hardening of a slurry, wherein the stucco comprises calcium sulfate hemihydrate, and the aqueous slurry comprises, on a dry basis, at least 60 weight percent of said calcium sulfate hemihydrate, 1,000,000 parts by weight of said calcium sulfate A gypsum board comprising from about 500 ppm to about 3000 ppm chloride anion per hemihydrate and a weight ratio of said water to calcium sulfate hemihydrate of from 0.2:1 to 1.2:1.

Article 16. 16. The gypsum board of clause 15, wherein the starch layer is a continuous starch layer over the entire inner surface of at least one of the front paper cover sheet and the back cover sheet.

Article 17. 17. Gypsum board according to clause 15 or 16, wherein the starch layer comprises uncooked starch.

Article 18. Gypsum board according to any one of clauses 15-17, wherein the starch layer comprises a mixture of uncooked and cooked starch.

Article 19. 19. The gypsum board of any one of clauses 15-18, wherein the aqueous slurry comprises from about 1000 ppm to about 3000 ppm chloride anion per 1,000,000 parts by weight of said calcium sulfate hemihydrate.

Clause 20. Gypsum board according to any one of clauses 15-19, wherein the starch layer is coated on the inner surface of the back cover sheet.

Clause 21. Gypsum board according to any one of clauses 15-20, wherein a starch layer is coated on the inner surface of the front paper cover sheet and the inner surface of the back cover sheet.

Article 22. A gypsum board according to any one of clauses 15-21, wherein the front paper cover sheet is the front paper cover sheet and the back paper cover sheet is the back paper cover sheet.

Article 23. wherein the board core comprises a low density region and at least one high density region, wherein the at least one high density region is inserted as a layer between the low density region and the front paper cover sheet or the back cover sheet. The gypsum board according to any one of 15-22.

Article 24. A first high density region arranged as the first layer contacting the front paper cover sheet or the starch layer coated thereon and the back paper cover sheet or the starch layer coated thereon, the low density region being arranged as the first layer. 24. The gypsum board of clause 23 sandwiched between a second high density region arranged as a second layer in contact with the gypsum board.

Article 25. 24. The gypsum board of clause 23, wherein the low density region is formed from a foamed gypsum slurry and includes a plurality of voids therein.

Article 26. 26. The gypsum board of any one of clauses 15-25, wherein the starch layer is coated on the inner surface in an amount of about 0.5 lbs/MSF to about 15 lbs/MSF.

Article 27. A gypsum board according to any one of clauses 15-26, wherein the set gypsum is formed from a synthetic gypsum comprising one or more chloride salts.

Article 28. (a) a board core comprising set gypsum formed from a first slurry comprising water and stucco containing a high salt impurity content, the core defining first and second core faces; (b) a skim coat layer defining first and second skim coat surfaces, the ski coat being formed from a second slurry comprising water, stucco, and skim coat starch; a skim coat layer, (c) a back coversheet disposed in bonded relationship to the core surface, the first side of the skim coat layer facing the back coversheet and the second side of the skim coat layer; a composite gypsum board comprising a back cover sheet facing the board core, wherein the skim-coated starch enhances the bond between the board core and the back cover sheet.

Article 29. 29. The composite gypsum board of clause 28, wherein the board further comprises a front coversheet with the second side of the board core facing the front coversheet.

Clause 30. A board has a second skim coat layer defining first and second faces, the second skim coat layer being formed from a third slurry comprising water, stucco, and skim coat starch; a second skim coat layer, the first side of the skim coat layer facing the second side of the board core and the second side of the second skim coat layer facing the second cover sheet 30. The composite gypsum board of clause 29, wherein the skim-coated starch enhances the bond between the board core and the front coversheet, and the second and third slurries may be the same or different.

Article 31. The first and/or second skim coat layer is about 1/8 inch to about 1/64 inch, such as about 1/12 inch to about 0.08 inch. 31. The composite gypsum board of any one of clauses 28-30, having a dry thickness of about 0.03 inch (1/32 inch).

Article 32. skim-coated starch in the second and/or third slurries from about 0.3% to about 8.0% by weight of the stucco, such as from about 1.0% to about 4.0% by weight of the stucco; A composite gypsum board according to any one of clauses 28-31, present in an amount.

Article 33. 33. The composite gypsum board of any one of clauses 28-32, wherein the high salt impurities comprise at least about 150 ppm chloride anions per 1,000,000 parts by weight of said calcium sulfate hemihydrate.

Article 34. 34. The composite gypsum board of any one of clauses 28-33, wherein the salt impurities comprise chloride salts such as sodium chloride, magnesium chloride or calcium chloride.

Article 35. 35. The composite gypsum board of any one of clauses 28-34, wherein the first slurry comprises core starch comprising pregelatinized starch and/or migratory starch having a molecular weight of about 6,000 Daltons or less.

Article 36. The skim-coated starch exhibits starch in a slurry comprising (i) a hydrothermal viscosity of from about 20 BU to about 300 BU by hydrothermal viscosity assay (HWVA method) and/or (ii) a starch concentration of 15% solids in water. Place and the starch is heated from 25° C. to 95° C. at a rate of 3° C./min, the slurry is held at 95° C. for 10 minutes, and the starch is cooled to 50° C. at a rate of −3° C./min, 75 rpm and 700 cmg 36. The method of any one of clauses 28-35 comprising uncooked starch having a moderate peak viscosity of about 120 BU to 1000 BU when measured by using a Viscograph-E instrument set to Composite gypsum board.

Article 37. the skim-coated starch has a viscosity of from about 20 centipoise to about 700 (e.g., from about 20 centipoise to about 300 centipoise or from about 30 centipoise to about 200 centipoise) when the viscosity is measured while subjecting the starch to conditions according to the VMA method; Composite gypsum board according to any one of clauses 28-36, comprising pregelatinized starch.

Article 38. A gypsum board comprising a set gypsum core disposed between a front cover sheet and a back cover sheet, the set gypsum core being formed from a slurry comprising water, stucco, and a high salt impurity content; Gypsum board, at least one of which is super absorbent paper.

Article 39. 39. The gypsum board of clause 38, further comprising a face skim coat disposed between the face coversheet and the set gypsum core.

Clause 40. 40. The gypsum board of clause 38 or 39, further comprising a back skim coat disposed between the back cover sheet and the set gypsum core.

Article 41. 41. Gypsum board according to clause 39 or 40, wherein the back cover sheet is super absorbent paper.

Article 42. The front and/or back skim coat is from about 0.125 inch (1/8 inch) to about 0.016 inch (1/64 inch), such as from about 0.08 inch (1/12 inch) to about 0.03 The gypsum board of any one of clauses 39-41, having a dry thickness of an inch (1/32 inch).

Article 43. 43. The gypsum board of any one of clauses 39-42, wherein the high salt impurities comprise at least about 150 ppm chloride anions per 1,000,000 parts by weight of said stucco.

Article 44. The gypsum board of any one of clauses 39-43, wherein the salt impurities comprise chloride salts such as sodium chloride, potassium chloride, magnesium chloride or calcium chloride.

Article 45. 45. The gypsum board of any one of clauses 39-44, wherein the superabsorbent paper has a bonded side Cobb value of at least about 2.1 g/100 cm ² according to the Cobb test.

Article 46. 46. The gypsum board of any one of clauses 39-45, wherein the superabsorbent paper has a bonded side Cobb value from about 2.1 g/100 cm ² to about 3.1 g/100 cm ² according to the Cobb test.

Article 47. Any of clauses 39-46, wherein the superabsorbent paper has a basis weight of from about 35 lb/MSF to about 65 lb/MSF, such as from about 38 lb/MSF to about 60 lb/MSF, such as from about 42 lb/MSF to about 55 lb/MSF or the gypsum board according to item 1.

Article 48. 48. The gypsum board of any one of clauses 39-47, wherein the super absorbent paper has a caliper of about 10 mils to about 15 mils.

Article 49. A gypsum board comprising a set gypsum core disposed between a front cover sheet and a back cover sheet, the set gypsum core being formed from a slurry comprising water, stucco, and a high salt impurity content, the board comprising: (a) at least one of the cover sheets, preferably the back cover sheet, is perforated; (b) at least one of the cover sheets, preferably the back cover sheet, is in the form of superabsorbent paper. (c) starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; and (d) (i) the first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; and (ii) a front skim coat layer defining the first and second faces, wherein the second face of the back skim coat faces the first core face, and , a top skim coat layer formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core; a front skim coat layer, the second side of the front skim coat layer facing the front cover sheet, the skim coat starch binding between the core and at least the back cover sheet; and the second and third slurries may be the same or different.

Clause 50. 50. The board of clause 49, wherein the high salt impurities comprise at least about 150 ppm chloride anions per 1,000,000 parts by weight of said stucco.

Article 51. 51. The board of clauses 49 or 50, wherein the salt impurities comprise chloride salts such as sodium chloride, potassium chloride, magnesium chloride, or calcium chloride.

Article 52. 52. The board of any one of clauses 49-51, wherein at least one of the first slurry, the second slurry and/or the third slurry contains boric acid.

Article 53. 53. The board of clause 52, wherein the boric acid is in an amount of about 0.01% to about 0.5% by weight of the stucco, such as about 0.05% to about 0.3% by weight of the stucco.

Article 54. At least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco 54. Board according to any one of clauses 49 to 53, containing clay, for example kaolin clay, in an amount of %.

Article 55. 55. The board of any one of clauses 49-54, wherein at least one of the first slurry, the second slurry and/or the third slurry contains polyphosphate.

Article 56. 56. The board of clause 55, wherein the polyphosphate is sodium trimetaphosphate.

Article 57. 57. The board of any one of clauses 49-56, wherein at least one of the first slurry, the second slurry and/or the third slurry contains a retardant.

Article 58. 58. A gypsum board according to any one of clauses 49-57, wherein the board comprises holes in the back cover sheet; and a back cover sheet in the form of superabsorbent paper.

Article 59. Clause 49, wherein the board comprises pores in the back cover sheet; and starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. 58. Gypsum board according to any one of claims 1 to 58.

Clause 60. the board defining holes in the back cover sheet; and (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being a second slurry comprising water, stucco, and skim coat starch. wherein the first side of the back skim coat faces the back cover sheet and the second side of the back ski coat faces the first core side; and (ii) A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and optionally skim coat starch; a top skim coat layer with one side facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, the skim coat starch covering the core 60. Gypsum board according to any one of clauses 49 to 59, which strengthens the bond between the gypsum board and at least the back cover sheet, and the second and third slurries may be the same or different.

Article 61. and a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. A gypsum board according to any one of clauses 49-59, comprising:

Article 62. The board is a back cover sheet in the form of a super absorbent paper; and (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch. a back skim coat layer formed from a second slurry, the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and optionally skim coat starch, a front skim coat layer, the first side of the skim coat layer facing the second side of the board core and the second side of the front skim coat layer facing the front cover sheet, the skim coat 60. A gypsum board according to any one of clauses 49-59, wherein the starch strengthens the bond between the core and at least the back cover sheet and the second and third slurries may be the same or different.

Article 63. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; and (i) first and second skim coats; A back skim coat layer defining a surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet. a back skim coat layer, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer, the second side of the layer facing the front cover sheet, the skim coat starch reinforcing the bond between the core and at least the back cover sheet; Gypsum board according to any one of clauses 49-59, wherein the slurries may be the same or different.

Article 64. a back cover sheet in the form of superabsorbent paper; and between at least one of the set gypsum core and the cover sheet, preferably at least between the back cover sheet and the set gypsum core. 60. Gypsum board according to any one of clauses 49-59, comprising starch present.

Article 65. The board comprises holes in the back coversheet; the back coversheet is in the form of an absorbent paper; and (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco and a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back coversheet and the second side of the back skim coat facing the first core side. and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and optionally skim coat starch. with the first side of the front skim coat layer facing the second side of the board core and the second side of the front skim coat layer facing the front cover sheet. 59, wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different. gypsum board according to the above paragraph.

Article 66. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; A back skim coat layer defining first and second skim coat surfaces, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat being the back skim coat layer; a back skim coat layer facing the cover sheet and the second side of the back ski coat facing the first core side; and (ii) a front skim coat layer defining the first and second sides. wherein a top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core; a top skim coat layer with a second side of the top skim coat layer facing the top cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; 59. Gypsum board according to any one of clauses 49-59, wherein the second and third slurries may be the same or different.

Article 67. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; and (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; defining a back skim coat layer, the side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; a top skim coat layer, the top skim coat layer being formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer being the second surface of the board core; and a second side of the top skim coat layer facing the top cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet and the second and third slurries may be the same or different.

Article 68. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side of the skim coat facing the back coversheet and the second side of the back skim coat facing the first core side, and (ii) first and second A front skim coat layer defining a surface of the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, the first surface of the front skim coat layer comprising: a top skim coat layer facing the second side of the board core, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch covering the core and at least the back cover sheet; and the second and third slurries may be the same or different; and, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 59. Gypsum board according to any one of clauses 49-59, comprising boric acid in an amount of 0.05% to about 0.3% by weight.

Article 69. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side of the skim coat facing the back coversheet and the second side of the back skim coat facing the first core side, and (ii) first and second A front skim coat layer defining a surface of the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, the first surface of the front skim coat layer comprising: a top skim coat layer facing the second side of the board core, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch covering the core and at least the back cover sheet; and the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, about 1 part of stucco. 59. Gypsum board according to any one of clauses 49 to 59, containing clay, eg kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, eg from about 1% to about 5% by weight of the stucco.

Clause 70. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side of the skim coat facing the back coversheet and the second side of the back skim coat facing the first core side, and (ii) first and second A front skim coat layer defining a surface of the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, the first surface of the front skim coat layer comprising: a top skim coat layer facing the second side of the board core, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch covering the core and at least the back cover sheet; and the second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1 weight of stucco; % to about 10% by weight, such as from about 1% to about 5% by weight of the stucco; the first slurry, the second slurry, and/or the third slurry. contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. or the gypsum board according to item 1.

Article 71. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side of the skim coat facing the back coversheet and the second side of the back skim coat facing the first core side, and (ii) first and second A front skim coat layer defining a surface of the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, the first surface of the front skim coat layer comprising: a top skim coat layer facing the second side of the board core, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch covering the core and at least the back cover sheet; and the second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1 weight of stucco; % to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 60. Gypsum board according to any one of clauses 49-59, wherein at least one of the slurries contains polyphosphate.

Article 72. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. and boric acid in an amount of, for example, from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. The gypsum board according to any one of 49-59.

Article 73. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. for example, from about 0.01% to about 0.5% by weight of the stucco, for example from about 0.05% to about 0.3% by weight of the stucco; At least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco 60. Gypsum board according to any one of clauses 49 to 59, containing clay, for example kaolin clay, in an amount of .

Article 74. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. for example, from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; at least one of the slurry of, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate. The gypsum board according to item 1.

Article 75. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. for example, from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; at least one of the slurry of, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second and/or at least one of the third slurry contains a retardant.

Article 76. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. for example, from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; at least one of the slurry of, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The gypsum board according to item 1.

Article 77. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. for example, from about 0.01% to about 0.5% by weight of the stucco, for example from about 0.05% to about 0.3% by weight of the stucco; 60. The gypsum board of any one of clauses 49-59, wherein at least one of the first slurry, the second slurry and/or the third slurry contains polyphosphate.

Article 78. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. for example, from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; Gypsum board according to any one of clauses 49-59, wherein at least one of the first slurry, the second slurry and/or the third slurry contains a retarder.

Article 79. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, about 1% to about 10% by weight of the stucco, such as 60. Gypsum board according to any one of clauses 49 to 59, containing clay, eg kaolin clay, in an amount of about 1% to about 5% by weight.

Article 80. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% to about 10% by weight of the stucco, such as about a clay, such as a kaolin clay, in an amount of 1% to about 5% by weight; and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate. The gypsum board according to any one of clauses 49-59.

Article 81. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% to about 10% by weight of the stucco, such as about clay, such as kaolin clay, in an amount from 1% to about 5% by weight; at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and at least one of the first slurry, the second slurry and/or the third slurry contains a retardant.

Article 82. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% to about 10% by weight of the stucco, such as about clay, such as kaolin clay, in an amount from 1% to about 5% by weight; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retarder. The gypsum board according to any one of clauses 49-59.

Article 83. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. gypsum board.

Article 84. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second slurry, and/or Or the gypsum board of any one of clauses 49-59, wherein at least one of the third slurries contains a retardant.

Article 85. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. gypsum board.

Article 86. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch strengthens the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and, for example, about 0.01 weight of stucco 59. Gypsum board according to any one of clauses 49 to 59, comprising boric acid in an amount of from % to about 0.5%, eg from about 0.05% to about 0.3% by weight of the stucco.

Article 87. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch strengthens the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; boric acid in an amount of from to about 0.5%, for example from about 0.05% to about 0.3% by weight of the stucco; Clause 49, wherein at least one of the slurries contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 60. The gypsum board according to any one of 1 to 59.

Article 88. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch strengthens the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; comprising boric acid in an amount of to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; the first slurry, the second slurry, and/or the third slurry at least one of which contains a clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; at least one of the slurry, the second slurry, and/or the third slurry contains polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry A gypsum board according to any one of clauses 49-59, wherein one contains a retardant.

Article 89. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; the first slurry, the second slurry, and/or the third slurry comprises boric acid in an amount of to about 0.5%, for example, from about 0.05% to about 0.3% by weight of the stucco; at least one of which contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 60. The gypsum board of any one of clauses 49-59, wherein at least one of the slurry of, the second slurry and/or the third slurry contains polyphosphate.

Article 90. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; the first slurry, the second slurry, and/or the third slurry comprises boric acid in an amount of to about 0.5%, for example, from about 0.05% to about 0.3% by weight of the stucco; at least one of which contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 60. The gypsum board of any one of clauses 49-59, wherein at least one of the slurry of, the second slurry and/or the third slurry contains a retardant.

Article 91. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; boric acid in an amount of from to about 0.5%, for example from about 0.05% to about 0.3% by weight of the stucco; 60. Gypsum board according to any one of clauses 49-59, wherein at least one of the slurries contains polyphosphate.

Article 92. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch strengthens the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; comprising boric acid in an amount of to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. or the gypsum board according to item 1.

Article 93. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; boric acid in an amount of from to about 0.5%, for example from about 0.05% to about 0.3% by weight of the stucco; Gypsum board according to any one of clauses 49-59, wherein at least one of the slurries contains a retardant.

Article 94. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and the first slurry, the second slurry and/or at least one of the third slurries comprises a clay, such as kaolin, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. Gypsum board according to any one of clauses 49-59, containing clay.

Article 95. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; the first slurry, the second slurry, and/or at least one of the third slurries is clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco and at least one of the first slurry, the second slurry and/or the third slurry contains a polyphosphate.

Article 96. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; the first slurry, the second slurry, and/or at least one of the third slurries is clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second slurry, and/or the third 60. The gypsum board according to any one of clauses 49-59, wherein at least one of the slurries of contains a retardant.

Article 97. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; the first slurry, the second slurry, and/or at least one of the third slurries is clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco and at least one of the first slurry, the second slurry and/or the third slurry contains a retarder.

Article 98. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and the first slurry, the second slurry , and/or at least one of the third slurries contains polyphosphate.

Article 99. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; the first slurry, the second slurry, and/or at least one of the third slurries contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. , gypsum board according to any one of clauses 49-59.

Clause 100. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and the first slurry, the second slurry , and/or at least one of the third slurries contains a retarder.

Clause 101. a backing coversheet in the form of superabsorbent paper; and, for example, from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.05% by weight of stucco. 59. Gypsum board according to any one of clauses 49-59, comprising boric acid in an amount of 0.3% by weight.

Clause 102. back cover sheet in the form of superabsorbent paper; for example from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0% by weight of stucco; and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco. 59. A gypsum board according to any one of clauses 49 to 59, containing clay, eg kaolin clay, in an amount of, eg, about 1% to about 5% by weight of the stucco.

Clause 103. back cover sheet in the form of superabsorbent paper; for example from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0% by weight of stucco; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco; For example, contains a clay, such as a kaolin clay, in an amount of about 1% to about 5% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry , polyphosphate.

Clause 104. back cover sheet in the form of superabsorbent paper; for example from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0% by weight of stucco; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco; For example, contains a clay, such as a kaolin clay, in an amount of about 1% to about 5% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry 59. Gypsum board according to any one of clauses 49 to 59, containing a retardant.

Clause 105. back cover sheet in the form of superabsorbent paper; for example from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0% by weight of stucco; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. The gypsum board according to item 1.

Article 106. back cover sheet in the form of superabsorbent paper; for example from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0% by weight of stucco; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and/or at least one of the third slurry contains a retardant.

Article 107. back cover sheet in the form of superabsorbent paper; for example from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0% by weight of stucco; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The gypsum board according to item 1.

Article 108. a back cover sheet in the form of superabsorbent paper; 59. Gypsum board according to any one of clauses 49 to 59, containing clay, eg kaolin clay, in an amount of about 1% to about 10%, eg about 1% to about 5% by weight of the stucco. .

Article 109. a board comprising holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; a clay, such as a kaolin clay, in an amount of 1% to about 10%, for example, about 1% to about 5% by weight of the stucco; 59. The gypsum board of any one of clauses 49-59, wherein at least one of the slurries of 3 contains polyphosphate.

Clause 110. a board comprising holes in the back cover sheet; a back cover sheet in the form of super absorbent paper; containing clay, such as kaolin clay, in an amount of 1% to about 10%, eg, about 1% to about 5%, by weight of the stucco; the first slurry, the second slurry, and/or the third contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The gypsum board according to any one of .

Article 111. a board comprising holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; a clay, such as a kaolin clay, in an amount of 1% to about 10%, for example, about 1% to about 5% by weight of the stucco; 59. The gypsum board of any one of clauses 49-59, wherein at least one of the slurries of 3 contains a retardant.

Article 112. a board comprising holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; and at least one of the first slurry, the second slurry, and/or the third slurry containing polyphosphate. , gypsum board according to any one of clauses 49-59.

Article 113. a board comprising holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; and at least one of the first slurry, the second slurry and/or the third slurry containing polyphosphate. and at least one of the first slurry, the second slurry and/or the third slurry contains a retardant.

Article 114. a board comprising holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; and at least one of the first slurry, the second slurry, and/or the third slurry containing a retardant. The gypsum board according to any one of clauses 49-59.

Article 115. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover; a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries may be the same or different; and, for example, from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco. 59. Gypsum board according to any one of clauses 49-59, comprising boric acid in an amount of % by weight.

Article 116. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; % boric acid; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco, for example, 60. Gypsum board according to any one of clauses 49-59, containing clay, such as kaolin clay, in an amount of about 1% to about 5% by weight of the stucco.

Article 117. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; % boric acid; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco, e.g. at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate in an amount of about 1% to about 5% by weight of the and at least one of the first slurry, the second slurry and/or the third slurry contains a retarder.

Article 118. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; % boric acid; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco, e.g. and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate in an amount of from about 1% to about 5% by weight of the The gypsum board according to any one of clauses 49-59, containing

Article 119. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; % boric acid; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco, e.g. and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant The gypsum board according to any one of clauses 49-59, containing

Clause 120. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; % boric acid; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. Gypsum board as described.

Article 121. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover; a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries may be the same or different; % amount of boric acid; at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second slurry, and/or at least one of the third slurries contains a retardant, gypsum board according to any one of clauses 49-59

Article 122. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover; a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries may be the same or different; % boric acid; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. Gypsum board as described.

Article 123. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover; a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; the second and third slurries may be the same or different; 60. Gypsum board according to any one of clauses 49 to 59, containing clay, eg kaolin clay, in an amount of about 10%, eg about 1% to about 5% by weight of the stucco.

Article 124. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover; a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; 10% by weight, such as from about 1% to about 5% by weight of the stucco, containing a clay, such as a kaolin clay; and of the first slurry, the second slurry, and/or the third slurry 59. Gypsum board according to any one of clauses 49 to 59, wherein at least one of contains a polyphosphate.

Article 125. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; of the first slurry, the second slurry, and/or the third slurry 60. Any one of clauses 49-59, wherein at least one contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The gypsum board described in .

Article 126. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; 10% by weight, such as from about 1% to about 5% by weight of the stucco, containing a clay, such as a kaolin clay; and of the first slurry, the second slurry, and/or the third slurry 59. Gypsum board according to any one of clauses 49-59, wherein at least one of contains a retardant.

Article 127. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover; a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; Clauses 49-, wherein the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate. 60. The gypsum board according to any one of 59.

Article 128. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; 60. The gypsum board of any one of clauses 49-59, wherein at least one of the slurry, the second slurry and/or the third slurry contains a retarder.

Article 129. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover; a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; Clauses 49-, wherein the two and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. 60. The gypsum board according to any one of 59.

Clause 130. starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; and, for example, stucco. Clause 49-59, comprising boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, for example from about 0.05% to about 0.3% by weight of the stucco. gypsum board.

Article 131. starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; boric acid in an amount of 0.01% to about 0.5%, for example, about 0.05% to about 0.3% by weight of the stucco; and the first slurry, the second slurry, and /or at least one of the third slurries comprises clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; A gypsum board according to any one of clauses 49-59, comprising:

Article 132. The board contains holes in the back cover sheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; the first slurry, the second slurry, and/or or at least one of the third slurries contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco and at least one of the first slurry, the second slurry and/or the third slurry contains polyphosphate.

Article 133. The board contains holes in the back cover sheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; the first slurry, the second slurry, and/or or at least one of the third slurries contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco and at least one of the first slurry, the second slurry and/or the third slurry contains a retardant.

Article 134. starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; boric acid in an amount of 0.01% to about 0.5%, for example, about 0.05% to about 0.3% by weight of the stucco; and the first slurry, the second slurry, and 60. The gypsum board of any one of clauses 49-59, wherein at least one of the third slurries contains polyphosphate.

Article 135. starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; the first slurry, the second slurry, and/or or at least one of the third slurries contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The gypsum board according to any one of 49-59.

Article 136. starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; boric acid in an amount of 0.01% to about 0.5%, for example, about 0.05% to about 0.3% by weight of the stucco; and the first slurry, the second slurry, and /or gypsum board according to any one of clauses 49-59, wherein at least one of the third slurries contains a retardant.

Article 137. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; and a first at least one of the slurry of, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. 60. Gypsum board according to any one of clauses 49-59, containing an amount of clay, such as kaolin clay.

Article 138. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; At least one of the slurry, the second slurry, and/or the third slurry in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco clay, such as kaolin clay; and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate. gypsum board according to the above paragraph.

Article 139. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; At least one of the slurry, the second slurry, and/or the third slurry in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second Gypsum board according to any one of clauses 49-59, wherein at least one of the slurry and/or the third slurry contains a retardant.

Clause 140. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; At least one of the slurry, the second slurry, and/or the third slurry in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. gypsum board according to the above paragraph.

Article 141. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; and a first 60. The gypsum board of any one of clauses 49-59, wherein at least one of the slurry of, the second slurry and/or the third slurry contains polyphosphate.

Article 142. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; at least one of the slurry, the second slurry, and/or the third slurry contains polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry A gypsum board according to any one of clauses 49-59, wherein one contains a retardant.

Article 143. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; and a first 60. The gypsum board of any one of clauses 49-59, wherein at least one of the slurry of, the second slurry and/or the third slurry contains a retardant.

Article 144. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and The second and third slurries may be the same or different; and for example from about 0.01% to about 0.5% by weight of the stucco, such as 60. The gypsum board of any one of clauses 49-59, comprising boric acid in an amount of from about 0.05% to about 0.3% by weight of the stucco.

Article 145. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and Strengthening the bond between at least the back cover sheet, the second and third slurries may be the same or different; boric acid in an amount of about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry, for example, 59. Clause 49-59, containing clay, such as kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. gypsum board.

Article 146. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and Strengthening the bond between at least the back cover sheet, the second and third slurries may be the same or different; boric acid in an amount of about 0.05% to about 0.3% by weight of the stucco; clay, such as kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; and the first slurry, the second slurry, and/or Or the gypsum board of any one of clauses 49-59, wherein at least one of the third slurries contains polyphosphate.

Article 147. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and Strengthening the bond between at least the back cover sheet, the second and third slurries may be the same or different; boric acid in an amount of about 0.05% to about 0.3% by weight of the stucco; clay, such as kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; and the first slurry, the second slurry, and/or Or the gypsum board of any one of clauses 49-59, wherein at least one of the third slurries contains a retardant.

Article 148. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and Strengthening the bond between at least the back cover sheet, the second and third slurries may be the same or different; boric acid in an amount of about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry comprises polyphosphate 597. The gypsum board according to any one of clauses 49-597, containing

Article 149. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and Strengthening the bond between at least the back cover sheet, the second and third slurries may be the same or different; boric acid in an amount of about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry comprises polyphosphate. and at least one of the first slurry, the second slurry and/or the third slurry contains a retarder.

Clause 50. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and Strengthening the bond between at least the back cover sheet, the second and third slurries may be the same or different; boric acid in an amount of about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry comprises a retarder The gypsum board according to any one of clauses 49-59, containing

Article 152. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet, the second and third slurries may be the same or different; contains clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. A gypsum board according to any one of the preceding paragraphs.

Article 152. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet and the second and third slurries may be the same or different; at least one containing a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 60. Gypsum board according to any one of clauses 49-59, wherein at least one of the second slurry and/or the third slurry contains polyphosphate.

Article 153. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet and the second and third slurries may be the same or different; at least one containing a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; at least one of the second slurry, and/or the third slurry contains polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardation 60. Gypsum board according to any one of clauses 49-59, containing an agent.

Article 154. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet and the second and third slurries may be the same or different; at least one containing a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; Gypsum board according to any one of clauses 49-59, wherein at least one of the second slurry and/or the third slurry contains a retardant.

Article 155. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet, the second and third slurries may be the same or different; 59. Gypsum board according to any one of clauses 49 to 59, wherein at least one of contains a polyphosphate.

Article 156. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet and the second and third slurries may be the same or different; 60. Any one of clauses 49-59, wherein at least one contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The gypsum board described in .

Article 157. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet, the second and third slurries may be the same or different; 59. Gypsum board according to any one of clauses 49-59, wherein at least one of contains a retardant.

Article 158. and boric acid in an amount such as from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. The gypsum board according to any one of clauses 49-59, comprising

Article 159. The board contains holes in the back cover sheet; for example boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 1% by weight of the stucco 59. Gypsum board according to any one of clauses 49 to 59, containing clay, for example kaolin clay, in an amount of about 5% by weight.

Article 160. The board is provided with holes in the back cover sheet; for example boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about Clauses 49-, containing clay, for example, kaolin clay in an amount of 5% by weight; and at least one of the first slurry, second slurry, and/or third slurry containing polyphosphate 60. The gypsum board according to any one of 59.

Article 161. The board is provided with holes in the back cover sheet; for example boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about Clauses 49-, wherein at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant, containing a clay, such as a kaolin clay, in an amount of 5% by weight; 60. The gypsum board according to any one of 59.

Article 162. The board contains holes in the back cover sheet; for example boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. and at least one of the first slurry, the second slurry and/or the third slurry contains polyphosphate.

Article 163. The board contains holes in the back cover sheet; for example boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, the second slurry, and/or the third slurry 59. Gypsum board according to any one of clauses 49-59, at least one of which contains a retardant.

Article 164. The board contains holes in the back cover sheet; for example boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. and at least one of the first slurry, the second slurry and/or the third slurry contains a retardant.

Article 165. the board includes holes in the back cover sheet; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco; 59. Gypsum board according to any one of clauses 49 to 59, for example containing clay, eg kaolin clay, in an amount of about 1% to about 5% by weight of the stucco.

Article 166. The board includes holes in the back cover sheet; , a clay, such as a kaolin clay, in an amount of about 1% to about 5% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry, Gypsum board according to any one of clauses 49-59, containing polyphosphate.

Article 167. The board includes holes in the back cover sheet; at least one of the first slurry, the second slurry, and/or the third slurry contains a poly 60. Gypsum board according to any one of clauses 49-59, containing a phosphate; and at least one of the first slurry, the second slurry and/or the third slurry containing a retarder. .

Article 168. 60. Any one of clauses 49-59, wherein the board includes holes in the back cover sheet; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. gypsum board according to the above paragraph.

Article 169. at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, the second Gypsum board according to any one of clauses 49-59, wherein at least one of the slurry and/or the third slurry contains a retarder.

Clause 170. any one of clauses 49-59, wherein the board includes holes in the back cover sheet; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. gypsum board according to the above paragraph.

Article 171. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; reinforcing, the second and third slurries may be the same or different; 60. Gypsum board according to any one of clauses 49-59, comprising boric acid in an amount of about 0.3% by weight.

Article 172. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco. 59. Gypsum board according to any one of clauses 49 to 59, containing clay, eg kaolin clay, in an amount of %, eg from about 1% to about 5% by weight of the stucco.

Article 173. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; including boric acid in an amount of 0.3% by weight; at least one of the first slurry, the second slurry, and/or the third slurry, for example, from about 1% to about 10% by weight of the stucco at least one of the first slurry, the second slurry, and/or the third slurry contains a clay, such as a kaolin clay, in an amount of, for example, about 1% to about 5% by weight of the stucco; , contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. gypsum board.

Article 174. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; including boric acid in an amount of 0.3% by weight; at least one of the first slurry, the second slurry, and/or the third slurry, for example, from about 1% to about 10% by weight of the stucco , e.g., a clay, e.g., kaolin clay, in an amount of from about 1% to about 5% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry. 59. Gypsum board according to any one of clauses 49 to 59, wherein one contains polyphosphate.

Article 175. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; including boric acid in an amount of 0.3% by weight; at least one of the first slurry, the second slurry, and/or the third slurry, for example, from about 1% to about 10% by weight of the stucco , e.g., a clay, e.g., kaolin clay, in an amount of from about 1% to about 5% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry. A gypsum board according to any one of clauses 49-59, wherein one contains a retardant.

Article 176. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. or the gypsum board according to item 1.

Article 177. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, the first 60. Gypsum board according to any one of clauses 49-59, wherein at least one of the second slurry and/or the third slurry contains a retardant.

Article 178. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; any of clauses 49-59, comprising boric acid in an amount of 0.3% by weight; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. or the gypsum board according to item 1.

Article 179. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; reinforcing, the second and third slurries may be the same or different; 59. Gypsum board according to any one of clauses 49-59, containing clay, eg kaolin clay, in an amount of 1% to about 10%, eg about 1% to about 5% by weight of the stucco.

Clause 180. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; % to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 60. The gypsum board of any one of clauses 49-59, wherein at least one of the slurries of contains polyphosphate.

Article 181. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; % to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; of clauses 49-59, wherein at least one of the slurries contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. A gypsum board according to any one of the preceding paragraphs.

Article 182. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; % to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 60. The gypsum board according to any one of clauses 49-59, wherein at least one of the slurries of contains a retardant.

Article 183. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; reinforcing, the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate , gypsum board according to any one of clauses 49-59.

Article 184. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; reinforcing, the second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; 60. The gypsum board of any one of clauses 49-59, wherein at least one of the first slurry, the second slurry and/or the third slurry contains a retardant.

Article 185. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; strengthen, the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant , gypsum board according to any one of clauses 49-59.

Article 186. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; and Any of clauses 49-59, for example comprising boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco The gypsum board according to item 1.

Article 187. a backing coversheet in which the board is in the form of a super absorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing cover sheet and the set gypsum core; , boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; and/or at least one of the third slurry contains clay, e.g. 59. Gypsum board according to any one of clauses 49 to 59, containing kaolin clay.

Article 188. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; , boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; At least one of the slurry and/or the third slurry contains clay, e.g. 60. The gypsum of any one of clauses 49-59, containing kaolin clay; and at least one of the first slurry, second slurry, and/or third slurry containing polyphosphate. board.

Article 189. a backing coversheet in which the board is in the form of a super absorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing cover sheet and the set gypsum core; , boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; At least one of the slurry and/or the third slurry contains clay, e.g., in an amount of from about 1% to about 10% by weight of the stucco, e.g. 60. The gypsum of any one of clauses 49-59, comprising kaolin clay; and at least one of the first slurry, second slurry, and/or third slurry comprising a retardant. board.

Article 190. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; , boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; and/or at least one of the third slurry contains polyphosphate.

Article 191. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; , boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; and/or at least one of the third slurry contains a retardant.

Article 192. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 59. Gypsum board according to any one of clauses 49 to 59, containing clay, eg kaolin clay, in an amount of 5% by weight.

Article 193. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; Clauses 49-59, containing a clay, such as a kaolin clay, in an amount of weight percent; and at least one of the first slurry, the second slurry, and/or the third slurry containing a polyphosphate. The gypsum board according to any one of .

Article 194. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry. 60. The gypsum board of any one of clauses 49-59, wherein at least one of the , second slurry and/or third slurry contains a retardant.

Article 195. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; Clauses 49-59, wherein at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant in an amount of weight percent clay, such as kaolin clay; The gypsum board according to any one of .

Article 196. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. and at least one of the first slurry, the second slurry and/or the third slurry contains polyphosphate.

Article 197. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, the second slurry, and/or the third slurry Gypsum board according to any one of clauses 49-59, at least one of which contains a retardant.

Article 198. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. and at least one of the first slurry, the second slurry and/or the third slurry contains a retardant.

Article 199. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; 59. The gypsum board of any one of clauses 49-59, comprising boric acid in an amount by weight of the stucco, such as from about 0.05% to about 0.3% by weight.

Clause 200. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; %, for example, from about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry. 59. Any one of clauses 49-59, wherein the clay, e.g., kaolin clay, in an amount, e.g., from about 1% to about 10%, e.g., from about 1% to about 5%, by weight of the stucco. gypsum board according to the above paragraph.

Clause 201. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; %, for example, from about 0.05% to about 0.3% by weight of the stucco; at least one of the first slurry, the second slurry, and/or the third slurry comprises a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 60. Gypsum board according to any one of clauses 49-59, wherein at least one of the slurry and/or the third slurry contains polyphosphate.

Clause 202. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; %, for example, from about 0.05% to about 0.3% by weight of the stucco; at least one of the first slurry, the second slurry, and/or the third slurry comprises a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; Gypsum board according to any one of clauses 49-59, wherein at least one of the slurry and/or the third slurry contains a retardant.

Clause 203. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; %, for example, from about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry. 59. Gypsum board according to any one of clauses 49 to 59, wherein one contains polyphosphate.

Clause 204. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; %, for example, from about 0.05% to about 0.3% by weight of the stucco; at least one of the first slurry, the second slurry, and/or the third slurry comprises , contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. gypsum board.

Clause 205. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; %, for example, from about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry. A gypsum board according to any one of clauses 49-59, wherein one contains a retardant.

Article 206. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and the first slurry, the second slurry, and/or the third contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. The gypsum board according to any one of 49-59.

Article 207. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; at least one of the slurries contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 60. The gypsum board of any one of clauses 49-59, wherein at least one of the first slurry, the second slurry and/or the third slurry contains polyphosphate.

Clause 208. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; at least one of the slurries contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry 59. Gypsum board according to any one of clauses 49-59, one of which contains a retardant.

Article 209. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; at least one of the slurries contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; Gypsum board according to any one of clauses 49-59, wherein at least one of the first slurry, the second slurry and/or the third slurry contains a retarder.

Clause 210. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and the first slurry, the second slurry, and/or the third 60. The gypsum board of any one of clauses 49-59, wherein at least one of the slurries of contains polyphosphate.

Article 211. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; of clauses 49-59, wherein at least one of the slurries contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. A gypsum board according to any one of the preceding paragraphs.

Article 212. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and the first slurry, the second slurry, and/or the third 60. The gypsum board according to any one of clauses 49-59, wherein at least one of the slurries of contains a retardant.

Article 213. The board comprises a backing cover sheet in the form of super absorbent paper; 60. Gypsum board according to any one of clauses 49-59, comprising an amount of boric acid.

Article 214. The board is a backing coversheet in the form of super absorbent paper; for example, in an amount of from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% to about 10% by weight of the stucco, such as about 60. Gypsum board according to any one of clauses 49 to 59, containing clay, eg kaolin clay, in an amount of 1% to about 5% by weight.

Article 215. The board is a backing coversheet in the form of super absorbent paper; for example, in an amount of from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco of boric acid; a clay, such as a kaolin clay, in an amount from weight percent to about 5 weight percent; and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate. , gypsum board according to any one of clauses 49-59.

Article 216. The board is a backing coversheet in the form of a superabsorbent paper; for example, in an amount of from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco of boric acid; a clay, such as a kaolin clay, in an amount from weight percent to about 5 weight percent; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. , gypsum board according to any one of clauses 49-59.

Article 217. The board is a backing coversheet in the form of a superabsorbent paper; for example, in an amount of from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate. board.

Article 218. The board is a backing coversheet in the form of a superabsorbent paper; for example, in an amount of from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second slurry, and/or 59. The gypsum board of any one of clauses 49-59, wherein at least one of the third slurries contains a retardant.

Article 219. The board is a backing coversheet in the form of a superabsorbent paper; for example, in an amount of from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco and at least one of the first slurry, the second slurry, and/or the third slurry contains a retarder. board.

Clause 220. and at least one of the first slurry, second slurry, and/or third slurry comprises, for example, from about 1% by weight of stucco to about 59. Gypsum board according to any one of clauses 49 to 59, containing clay, eg kaolin clay, in an amount of 10% by weight, eg from about 1% to about 5% by weight of the stucco.

Article 221. The board includes a back cover sheet in the form of super absorbent paper; %, for example, from about 1% to about 5% by weight of the stucco; and of the first slurry, the second slurry, and/or the third slurry. 59. Gypsum board according to any one of clauses 49-59, at least one of which contains a polyphosphate.

Article 222. The board includes a back cover sheet in the form of super absorbent paper; %, for example, from about 1% to about 5% by weight of the stucco; 60. Any one of clauses 49-59, wherein one contains the polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. Gypsum board as described.

Article 223. The board includes a back cover sheet in the form of superabsorbent paper; %, for example, from about 1% to about 5% by weight of the stucco; and of the first slurry, the second slurry, and/or the third slurry. 59. Gypsum board according to any one of clauses 49-59, at least one of which contains a retardant.

Article 224. of clauses 49-59, wherein the board comprises a back cover sheet in the form of superabsorbent paper; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. A gypsum board according to any one of the preceding paragraphs.

Article 225. The board includes a back cover sheet in the form of superabsorbent paper; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry 60. The gypsum board of any one of clauses 49-59, wherein at least one of the , second slurry and/or third slurry contains a retardant.

Article 226. Clauses 49-59, wherein the board comprises a back cover sheet in the form of superabsorbent paper; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The gypsum board according to any one of .

Article 227. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; may be the same or different; and boron in an amount of, for example, from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. Gypsum board according to any one of clauses 49-59, comprising an acid.

Article 228. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% to about 10% by weight of the stucco, such as about 1% by weight of the stucco 59. Gypsum board according to any one of clauses 49 to 59, containing clay, such as kaolin clay, in an amount of to about 5% by weight.

Article 229. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 1% by weight of the stucco Clause 49, containing clay, e.g., kaolin clay, in an amount of about 5% by weight; and at least one of the first slurry, second slurry, and/or third slurry containing polyphosphate. 60. The gypsum board according to any one of 1 to 59.

Clause 230. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 1% by weight of the stucco Clause 49, containing clay, e.g., kaolin clay, in an amount of about 5% by weight; and at least one of the first slurry, the second slurry, and/or the third slurry containing a retardant. 60. The gypsum board according to any one of -59.

Article 231. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; and at least one of the first slurry, the second slurry and/or the third slurry contains polyphosphate.

Article 232. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, the second slurry, and/or the third Gypsum board according to any one of clauses 49-59, wherein at least one of the slurries contains a retardant.

Article 233. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; and at least one of the first slurry, the second slurry and/or the third slurry contains a retardant.

Article 234. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably between at least the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% to about 10% by weight of the stucco, such as 59. Gypsum board according to any one of clauses 49 to 59, containing clay, for example kaolin clay, in an amount of from about 1% to about 5% by weight of the stucco.

Article 235. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; clay, such as kaolin clay, in an amount of about 1% to about 5% by weight of the stucco; Gypsum board according to any one of clauses 49-59, containing phosphate.

Article 236. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; clay, such as kaolin clay, in an amount of from about 1% to about 5% by weight of the stucco; at least one of the first slurry, the second slurry, and/or the third slurry comprises a polyphosphate; and at least one of the first slurry, the second slurry and/or the third slurry contains a retarder.

Article 237. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. The gypsum board described in .

Article 238. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second slurry , and/or at least one of the third slurries contains a retarder.

Article 239. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The gypsum board described in .

Clause 240. starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; and, for example, about 0.01% by weight of the stucco. 59. The gypsum board of any one of clauses 49-59, comprising boric acid in an amount of from about 0.5% by weight of the stucco, for example from about 0.05% to about 0.3% by weight of the stucco.

Article 241. Starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; for example, from about 0.01% by weight of the stucco boric acid in an amount of about 0.5% by weight, such as from about 0.05% to about 0.3% by weight of the stucco; and the first slurry, the second slurry, and/or the third slurry. contains clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. 60. The gypsum board according to any one of 59.

Article 242. Starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; for example, from about 0.01% by weight of the stucco of the first slurry, the second slurry, and/or the third slurry; at least one of which contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 60. The gypsum board of any one of clauses 49-59, wherein at least one of the slurry, the second slurry and/or the third slurry contains polyphosphate.

Article 243. Starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; for example, from about 0.01% by weight of the stucco of the first slurry, the second slurry, and/or the third slurry; at least one of which contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 60. The gypsum board of any one of clauses 49-59, wherein at least one of the slurry, the second slurry and/or the third slurry contains a retarder.

Article 244. Starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; for example, from about 0.01% by weight of the stucco boric acid in an amount of about 0.5% by weight, such as from about 0.05% to about 0.3% by weight of the stucco; and the first slurry, the second slurry, and/or the third slurry. 59. Gypsum board according to any one of clauses 49-59, at least one of which contains a polyphosphate.

Article 245. starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; for example, from about 0.01% by weight of stucco; of the first slurry, the second slurry, and/or the third slurry; any of clauses 49-59, at least one of which contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The gypsum board according to item 1.

Article 246. Starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; for example, from about 0.01% by weight of the stucco boric acid in an amount of about 0.5% by weight, such as from about 0.05% to about 0.3% by weight of the stucco; and the first slurry, the second slurry, and/or the third slurry. 59. Gypsum board according to any one of clauses 49-59, at least one of which contains a retardant.

Article 247. The board comprises starch contained between at least one of the set gypsum core and the cover sheet, preferably at least between the back cover sheet and the set gypsum core; At least one of the slurry and/or the third slurry contains clay, e.g. 60. Gypsum board according to any one of clauses 49-59, containing kaolin clay.

Article 248. The board comprises starch contained between at least one of the set gypsum core and the cover sheets, preferably at least between the back cover sheet and the set gypsum core; first slurry, second slurry and/or at least one of the third slurries comprises a clay, such as kaolin, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. 60. Gypsum board according to any one of clauses 49 to 59, containing clay; and at least one of the first slurry, second slurry and/or third slurry containing polyphosphate. .

Article 249. The board comprises starch contained between at least one of the set gypsum core and the cover sheets, preferably at least between the back cover sheet and the set gypsum core; first slurry, second slurry and/or at least one of the third slurries comprises a clay, such as kaolin, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second slurry, and/or the 59. The gypsum board of any one of clauses 49-59, wherein at least one of the slurries of 3 contains a retardant.

Clause 250. The board comprises starch contained between at least one of the set gypsum core and the cover sheets, preferably at least between the back cover sheet and the set gypsum core; first slurry, second slurry and/or at least one of the third slurries comprises a clay, such as kaolin, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. 60. Gypsum board according to any one of clauses 49-59, containing clay; and at least one of the first slurry, second slurry and/or third slurry containing a retarder. .

Article 251. The board comprises starch contained between at least one of the set gypsum core and the cover sheets, preferably at least between the back cover sheet and the set gypsum core; Gypsum board according to any one of clauses 49 to 59, wherein at least one of the slurry and/or the third slurry contains polyphosphate.

Article 252. The board comprises starch contained between at least one of the set gypsum core and the cover sheets, preferably at least between the back cover sheet and the set gypsum core; first slurry, second slurry and/or at least one of the third slurry contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retarder. The gypsum board according to any one of clauses 49-59.

Article 253. The board comprises starch contained between at least one of the set gypsum core and the cover sheets, preferably at least between the back cover sheet and the set gypsum core; Gypsum board according to any one of clauses 49-59, wherein at least one of the slurry and/or the third slurry contains a retarder.

Article 254. A board has (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, a first side of the front skim coat layer facing the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet The second and third slurries may be the same or different; and for example from about 0.01% to about 0.5% by weight of the stucco, such as about 0.5% by weight of the stucco, for example about 0.5% by weight of the stucco. 59. The gypsum board of any one of clauses 49-59, comprising boric acid in an amount of 05% to about 0.3% by weight.

Article 255. A board has (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, a first side of the front skim coat layer facing the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet The second and third slurries may be the same or different; for example, about 0.01% to about 0.5% by weight of stucco, such as about 0.05% by weight of stucco. and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% by weight of the stucco. 59. Gypsum board according to any one of clauses 49 to 59, containing clay, eg kaolin clay, in an amount of from about 10%, eg from about 1% to about 5% by weight of the stucco.

Article 256. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet to strengthen the bond between the second and third slurries, which may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 1% by weight of the stucco; a clay, such as a kaolin clay, in an amount of about 10% by weight, such as from about 1% to about 5% by weight of the stucco; and of the first slurry, the second slurry, and/or the third slurry 59. Gypsum board according to any one of clauses 49-59, at least one of which contains a polyphosphate.

Article 257. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet to strengthen the bond between the second and third slurries, which may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 1% by weight of the stucco; a clay, such as a kaolin clay, in an amount of about 10% by weight, such as from about 1% to about 5% by weight of the stucco; and of the first slurry, the second slurry, and/or the third slurry Gypsum board according to any one of clauses 49-59, at least one of which contains a retardant.

Article 258. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet to strengthen the bond between the second and third slurries, which may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate, clause 49. 60. The gypsum board according to any one of 1 to 59.

Article 259. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet to strengthen the bond between the second and third slurries, which may be the same or different; % to about 0.3% by weight; at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; 60. The gypsum board of any one of clauses 49-59, wherein at least one of the slurry of, the second slurry and/or the third slurry contains a retardant.

Article 260. A board has (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, a first side of the front skim coat layer facing the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet The second and third slurries may be the same or different; for example, about 0.01% to about 0.5% by weight of stucco, such as about 0.05% by weight of stucco. and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant, clause 49. 60. The gypsum board according to any one of 1 to 59.

Article 261. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third 59, containing clay, such as kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. gypsum board.

Article 262. A board has (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, a first side of the front skim coat layer facing the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet The second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry may, for example, a clay, such as a kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; and the first slurry, the second slurry, and 60. The gypsum board of any one of clauses 49-59, wherein at least one of the third slurries contains polyphosphate.

Article 263. A board has (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, a first side of the front skim coat layer facing the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet The second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry may, for example, a clay, such as a kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; the first slurry, the second slurry, and/or or at least one of the third slurries contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The gypsum board according to any one of 49-59.

Article 264. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet The second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry may, for example, a clay, such as a kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; and the first slurry, the second slurry, and /or gypsum board according to any one of clauses 49-59, wherein at least one of the third slurries contains a retardant.

Article 265. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet and the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third Gypsum board according to any one of clauses 49-59, containing phosphate.

Article 266. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet the second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises polyphosphate and at least one of the first slurry, the second slurry and/or the third slurry contains a retarder.

Article 267. A board has (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, a first side of the front skim coat layer facing the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third 60. Gypsum board according to any one of clauses 49-59, containing an agent.

Article 268. At least one of the first slurry, the second slurry, and/or the third slurry contains, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 0.05% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% by weight of the stucco. 59. Gypsum board according to any one of clauses 49 to 59, containing clay, eg kaolin clay, in an amount of from about 10%, eg from about 1% to about 5% by weight of the stucco.

Article 269. At least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 0.05% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 1% by weight of the stucco; a clay, such as a kaolin clay, in an amount of about 10% by weight, such as from about 1% to about 5% by weight of the stucco; and of the first slurry, the second slurry, and/or the third slurry 59. Gypsum board according to any one of clauses 49-59, at least one of which contains a polyphosphate.

Article 270. At least one of the first slurry, the second slurry, and/or the third slurry contains, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 0.05% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 1% by weight of the stucco; a clay, such as a kaolin clay, in an amount of about 10% by weight, such as from about 1% to about 5% by weight of the stucco; and of the first slurry, the second slurry, and/or the third slurry Gypsum board according to any one of clauses 49-59, at least one of which contains a retardant.

Article 271. At least one of the first slurry, the second slurry, and/or the third slurry contains, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 0.05% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate, clause 49. 60. The gypsum board according to any one of -59.

Article 272. At least one of the first slurry, the second slurry, and/or the third slurry contains, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 0.05% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first 60. The gypsum board of any one of clauses 49-59, wherein at least one of the slurry of, the second slurry and/or the third slurry contains a retardant.

Article 273. At least one of the first slurry, the second slurry, and/or the third slurry contains, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 0.05% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant, clause 49. 60. The gypsum board according to any one of -59.

Article 274. At least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco % amount of clay, such as kaolin clay; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. A gypsum board according to any one of the preceding paragraphs.

Article 275. At least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco % amount of clay, such as kaolin clay; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, Gypsum board according to any one of clauses 49-59, wherein at least one of the second slurry and/or the third slurry contains a retardant.

Article 276. At least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco % amount of clay, such as kaolin clay; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, Gypsum board according to any one of clauses 49-59, wherein at least one of the second slurry and/or the third slurry contains a retardant.

Article 277. At least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco % amount of clay, such as kaolin clay; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. A gypsum board according to any one of the preceding paragraphs.

Article 278. at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and of the first slurry, the second slurry, and/or the third slurry 59. Gypsum board according to any one of clauses 49-59, wherein at least one of contains a retardant.

Article 279. 1. A method of making a gypsum board, comprising: an aqueous slurry comprising a mixture of water and stucco, wherein the stucco comprises calcium sulfate hemihydrate, said calcium sulfate hemihydrate being at least 60 weight percent on a dry basis. from about 500 ppm to about 3000 ppm chloride anion per 1,000,000 parts by weight of said calcium sulfate hemihydrate, and a weight ratio of water to calcium sulfate hemihydrate of from 0.2:1 to 1.2 and an aqueous slurry between a front coversheet and a back coversheet, each coversheet having an inner surface and an outer surface, the back coversheet comprising: disposing an aqueous slurry comprising a plurality of perforations therethrough and contacting the inner surfaces of the front and back cover sheets; and curing the calcium sulfate hemihydrate to form a board core comprising calcium sulfate dihydrate. A method comprising forming a panel comprising a layer, drying the panel, and cutting the panel into gypsum board having one or more predetermined dimensions.

Clause 280. 280. The method of Clause 279, further comprising introducing a plurality of holes in the back cover sheet with a wallboard punching device.

Article 281. 281. The method of clause 279 or 280, wherein the plurality of holes are present in the back coversheet before the back coversheet contacts the aqueous slurry.

Article 282. 282. The method of any one of clauses 279-281, wherein the paper for the backing paper coversheet is fed from a roller and a plurality of holes are present in the backing coversheet prior to contacting the backing coversheet with the aqueous slurry.

Article 283. 283. The method of any one of clauses 279-282, wherein at least a portion of the aqueous slurry is in a foamed state while being disposed between the front coversheet and the back coversheet.

Article 284. Any of clauses 279-283, wherein the calcium sulfate hemihydrate comprises synthetic gypsum comprising one or more chloride salts, wherein the one or more chloride salts provide at least a portion of the chloride anions. or the method described in paragraph 1.

Article 285. 1. A method of making a gypsum board, comprising: an aqueous slurry comprising a mixture of water and stucco, wherein the stucco comprises calcium sulfate hemihydrate, said calcium sulfate hemihydrate being at least 60 weight percent on a dry basis. from about 500 ppm to about 3000 ppm chloride anion per 1,000,000 parts by weight (pbw) of said calcium sulfate hemihydrate, and a water to calcium sulfate hemihydrate weight ratio of from 0.2:1 Preparing an aqueous slurry comprising a 1.2:1 mixture of water and an aqueous slurry between a front paper cover sheet and a back cover sheet, each cover sheet having an inner surface and an outer surface, the front side an inner surface of at least one of the paper cover sheet and the backing paper cover sheet being coated with a starch layer, placing an aqueous slurry in contact with the starch layer and curing the calcium sulfate hemihydrate; A method comprising forming a panel including a gypsum core comprising calcium sulfate dihydrate, drying the panel, and cutting the panel into gypsum boards having one or more predetermined dimensions.

Article 286. 286. The method of clause 285, further comprising applying a starch layer to the inner surface of at least one of the front paper cover sheet and the back paper cover sheet as a continuous starch layer covering the entire inner surface.

Article 287. Clause 285, further comprising applying a starch layer to the inner surface of at least one of the front paper cover sheet and the back paper cover sheet as a continuous starch layer covering the entire inner surface, the back paper cover sheet having holes. or the method according to 286.

Article 288. 288. The method of any one of clauses 285-287, wherein at least a portion of the gypsum slurry is in a foamed state while being disposed between the front paper cover sheet and the back cover sheet.

Article 289. A first portion of the gypsum slurry is disposed in an unexpanded state as a first dense region in layered form in contact with the front paper cover sheet or the starch layer thereon, and a second portion of the gypsum slurry is disposed in the first 289. The method of any one of clauses 285-288, wherein the low density region is placed in a foamed state as a low density region in contact with the high density region of the.

Clause 290. 289. The method of any one of clauses 285-289, wherein the calcium sulfate hemihydrate comprises synthetic gypsum comprising one or more chloride salts.

Article 291. A method of making a composite gypsum board comprising: (a) mixing at least water and stucco containing a high salt impurity content to form a core slurry; optionally mixing the skim coat starch to form a top skim coat slurry; and (c) placing the top skim coat slurry against the top cover sheet in bonded relationship to form a slurry surface and a cover sheet surface. and (d) placing a core slurry in bonded relationship to the surface composite to form a core composite, the core slurry having first and second surfaces. with the first side facing the slurry surface of the face composite; and (e) mixing water, stucco, and skim coat starch to form a back skim coat slurry wherein the front and back skim coat slurries may be the same or different; and a coversheet surface; and (g) placing the backing composite in bonded relationship to the core composite to form a board precursor, the backing composite comprising: (h) drying the board precursor to form a board, wherein the skim-coated starch is applied to the board core and the back cover; strengthening the bond between the sheet and optionally between the board core and the first cover sheet.

Article 292. The core starch is the pregelatinized starch in an amount of about 0.5% to about 1.5% by weight of the stucco, and the skim coat starch is the pregelatinized starch in an amount of about 1.5% to about 5% by weight of the stucco. 292. The method of clause 291, which is a cooked starch.

Article 293. The first and/or second skim coat layer is about 1/8 inch to about 1/64 inch, such as about 1/12 inch to about 0.083 inch. 293. The method of clause 291 or 292, having a dry thickness of about 0.031 inch (1/32 inch).

Article 294. skim-coated starch in the second and/or third slurries from about 0.3% to about 8.0% by weight of the stucco, such as from about 1.0% to about 4.0% by weight of the stucco; 294. The method of any one of clauses 291-293, present in an amount.

Article 295. 295. The method of any one of clauses 291-294, wherein the first slurry comprises at least about 150 ppm chloride anion per 1,000,000 parts by weight of said calcium sulfate hemihydrate.

Article 296. 296. The method of any one of clauses 291-295, wherein the salt impurity is a chloride salt such as sodium chloride, magnesium chloride, or calcium chloride.

Article 297. 297. The method of any one of clauses 291-296, wherein the core starch comprises pregelatinized starch and/or migratory starch having a molecular weight of about 6,000 Daltons or less.

Article 298. The skim-coated starch exhibits starch in a slurry comprising (i) a hydrothermal viscosity of about 20 BU to about 300 BU by hydrothermal viscosity assay (HWVA method) and/or (ii) a starch concentration of 15% solids in water. Place and the starch is heated from 25° C. to 95° C. at a rate of 3° C./min, the slurry is held at 95° C. for 10 minutes, and the starch is cooled to 50° C. at a rate of −3° C./min, 75 rpm and 700 cmg 298. The method of any one of clauses 291-297, comprising uncooked starch having a moderate peak viscosity of about 120 BU to 1000 BU when measured by using a Viscograph-E instrument set to Method.

Article 299. The skim-coated starch has a viscosity of from about 20 centipoise to about 700 centipoise (e.g., from about 20 centipoise to about 300 centipoise or from about 30 centipoise to about 200 centipoise) when the viscosity is measured while subjecting the starch to conditions according to the VMA method. , pregelatinized starch.

Clause 300. A method of making a gypsum board comprising: (a) mixing stucco containing at least water and a high salt impurity content to form a core slurry; forming a board core in mating relation to the coversheet, the board core having a first side and a second side, the first side facing the front coversheet; and (c) applying a back coversheet in bonded relationship to the second side of the board core to form a board precursor, wherein at least one of the coversheets is superabsorbent paper. and (d) drying the board precursor to form a board.

Clause 301. 301. The method of clause 300, further comprising applying a second slurry comprising at least stucco and water to the front cover to form a front skim coat disposed between the front coversheet and the board core.

Clause 302. applying a third slurry comprising at least stucco and water to the backing paper to form a back skim coat disposed between the back cover sheet and the board core, wherein the second and third slurries are the same; or different, the method of clause 300 or 301, further comprising forming.

Clause 303. 303. The method of any one of clauses 300-302, wherein the back cover sheet is super absorbent paper.

Clause 304. The front and/or back skim coat is from about 0.125 inch (1/8 inch) to about 0.016 inch (1/64 inch), such as from about 0.08 inch (1/12 inch) to about 0.03 304. The method of any one of clauses 300-303, having a dry thickness of an inch (1/32 inch).

Clause 305. 305. The process of any one of clauses 300-304, wherein the high salt impurities comprise at least about 150 ppm chloride anions per 1,000,000 parts by weight of said stucco.

Article 306. 306. The method of any one of clauses 300-305, wherein the salt impurities comprise chloride salts such as sodium chloride, potassium chloride, magnesium chloride, or calcium chloride.

Clause 307. 307. The method of any one of clauses 300-306, wherein the superabsorbent paper has a bonded side Cobb value of at least about 2.1 g/100 cm ² by the Cobb test.

Clause 308. 308. The method of any one of clauses 300-307, wherein the superabsorbent paper has a bonded side Cobb value of from about 2.1 g/100 cm ² to about 3.1 g/100 cm ² by the Cobb test.

Article 309. Any of clauses 300-308, wherein the superabsorbent paper has a basis weight of from about 40 lb/MSF to about 65 lb/MSF, such as from about 42 lb/MSF to about 60 lb/MSF, such as from about 45 lb/MSF to about 55 lb/MSF or the method described in paragraph 1.

Clause 310. 309. The method of any one of clauses 300-309, wherein the superabsorbent paper has a caliper of about 10 mils to about 15 mils.

Article 311. A method of making a gypsum board comprising: (a) mixing at least water and stucco containing a high salt impurity content to form a core slurry; and (b) at least water, stucco, and optionally (c) disposing the front skim coat slurry against the front coversheet in bonded relationship to have a slurry surface and a coversheet surface; forming a surface composite; and (d) placing a core slurry in bonded relationship to the surface composite to form a core composite, wherein the core slurry covers the first and second surfaces. forming a board core having a first side facing the slurry surface of the surface composite; and (e) mixing water, stucco, and optionally skim-coated starch, forming a back skim coat slurry, wherein the front and back skim coat slurries may be the same or different; and (f) placing the back skim coat slurry in bonded relationship to the back cover sheet. (g) placing the backing composite in bonded relationship to the core composite to form a board precursor, comprising: (h) drying the board precursor in a kiln to form a board, comprising: (i) perforating at least one of the cover sheets, preferably the back cover sheet; and (j) at least one of the cover sheets, preferably the back cover sheet, being in the form of superabsorbent paper; (k) applying starch between the set gypsum core and at least one of the cover sheets, preferably between at least the back cover sheet and the set gypsum core; Including skim-coated starch in the second and/or third slurries to strengthen the bond between the board core, the face and/or (m) drying at least one in-kiln high frequency moisture sensor in communication with a controller outside the kiln; Using the kiln contained therein to generate an in-kiln moisture reading, (i) an upstream high frequency moisture sensor, and a relative high frequency moisture sensor; The moisture content in the board is measured upstream of the kiln using an upstream sensor that is less susceptible to high salinity during rallying and is in communication with the controller to determine the first upstream moisture content. respectively generating a reading and a second upstream moisture reading; and (ii) an upstream high frequency moisture sensor and a moisture reading from the upstream sensor that is less susceptible to high salt concentrations in the slurry than the high frequency moisture sensor. and (iii) biasing the in-kiln high frequency moisture sensor to correct for any error in the in-kiln moisture reading when a delta exists between the first and second moisture readings. and drying.

Article 312. 312. The method of clause 311, wherein the high salt impurities comprise at least about 150 ppm chloride anions per 1,000,000 parts by weight of said stucco.

Article 313. 313. The method of Clause 311 or 312, wherein the salt impurity comprises a chloride salt such as sodium chloride, potassium chloride, magnesium chloride, or calcium chloride.

Article 314. 314. The method of any one of clauses 311-313, wherein at least one of the first slurry, the second slurry and/or the third slurry contains boric acid.

Article 315. Any one of clauses 311-314, wherein the boric acid is in an amount from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. The method described in section.

Article 316. At least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco 316. A method according to any one of clauses 311 to 315, containing a clay, such as a kaolin clay, in an amount of %.

Article 317. 317. The method of any one of clauses 311-316, wherein at least one of the first slurry, the second slurry and/or the third slurry contains polyphosphate.

Article 318. 97. The method of clause 96, wherein the polyphosphate is sodium trimetaphosphate.

Article 319. 319. The method of any one of clauses 311-318, wherein at least one of the first slurry, the second slurry and/or the third slurry contains a retardant.

Clause 320. drying comprises (a) a downstream high frequency moisture sensor and a downstream sensor that is less susceptible to high salt concentrations in the slurry compared to the high frequency moisture sensor, the downstream high frequency sensor and the microwave sensor being in communication with the controller; using to measure the moisture content in the board downstream of the kiln to generate a first downstream moisture reading and used to bias a second upstream moisture reading; (c) adjusting the burner output and/or the air system; and adjusting the temperature in the kiln to reduce heating therein.

Article 321. 321. The method of clause 320, wherein the setpoint controls burner power/temperature and/or airflow within the kiln.

Article 322. 322. The method of any one of clauses 311-321, wherein at least one of the sensors that are less susceptible to high salt concentrations in the slurry compared to high frequency moisture sensors is a microwave sensor.

Article 323. 323. The method of any one of clauses 311-322, wherein at least one of the radio frequency sensors is a dielectric sensor.

Article 324. 324. The method of any one of clauses 311-323, wherein the controller is a programmable logic controller.

Article 325. 325. The method of any one of clauses 311-324, wherein the kiln has one zone.

Article 326. 325. The method of any one of clauses 311-325, wherein the kiln has at least two zones.

Article 327. 326. The method of any one of clauses 311-326, wherein the kiln contains at least two in-kiln moisture sensors.

Article 328. 1. A method of making a gypsum board comprising: (a) mixing at least water, stucco, and foam to form a first slurry; (c) cutting the board precursor into boards; (d) at least one in-kiln high frequency moisture sensor and a controller outside the kiln; drying the board in a kiln containing therein a kiln moisture sensor in communication with to generate a kiln moisture reading; and (e) the upstream high frequency moisture sensor and compared to the high frequency moisture sensor Measuring the moisture content in the board upstream of the kiln using an upstream sensor that is insensitive to high salt concentrations in the slurry and in communication with the controller to determine the first upstream moisture generating a reading and a second upstream moisture reading, respectively; and (f) an upstream high frequency moisture sensor and a moisture reading from the upstream sensor that is less susceptible to high salt concentrations in the slurry than the high frequency moisture sensor. and (g) biasing the in-kiln high frequency moisture sensor to correct for any error in the in-kiln moisture reading when a delta exists between the first and second moisture readings. A method, including doing.

Article 329. where the kiln has burner power and/or air extraction associated therewith, and the method has (a) a downstream high frequency moisture sensor and a downstream sensor that is less susceptible to high salt concentrations in the slurry compared to the high frequency moisture sensor; measuring the moisture content in the board downstream of the kiln using a downstream radio frequency sensor and a microwave sensor in communication with the controller to obtain a first downstream moisture reading and a second downstream moisture reading; (b) correlating moisture readings from downstream high frequency moisture sensors and downstream sensors that are less susceptible to high salt concentrations in the slurry compared to high frequency moisture sensors; 328. The method of clause 328, further comprising: adjusting the burner power and/or the air system to adjust the temperature in the kiln to reduce heating therein.

Article 330. 329. The method of clause 329, wherein the set points control burner power, temperature, and/or airflow within the kiln.

Article 331. 331. The method of any one of clauses 328-330, wherein at least one of the sensors that are less susceptible to high salt concentrations in the slurry than high frequency moisture sensors is a microwave sensor.

Article 332. 332. The method of any one of clauses 328-331, wherein at least one of the high frequency sensors produces a dielectric reading.

Article 333. 333. The method of any one of clauses 328-332, wherein the controller is a programmable logic controller.

Article 334. 333. The method of any one of clauses 328-333, wherein the kiln has one zone.

Article 335. 335. The method of any one of clauses 328-334, wherein the kiln has at least two zones.

Article 336. 336. The method of any one of clauses 328-335, wherein the kiln contains at least two in-kiln moisture sensors.

Article 337. 337. The process of any one of clauses 328-336, wherein the high salt impurities comprise at least about 150 ppm chloride anions per 1,000,000 parts by weight of said stucco.

Article 338. 338. The method of any one of clauses 328-337, wherein the salt impurities comprise chloride salts such as sodium chloride, potassium chloride, magnesium chloride, or calcium chloride.

Article 339. 339. Any one of clauses 328-338, further comprising applying a second slurry comprising at least stucco and water to the cover sheet to form a front skim coat disposed between the front cover sheet and the board core. described method.

Article 340. applying a third slurry comprising at least stucco and water to the backing paper to form a back skim coat disposed between the back cover sheet and the board core, wherein the second and third slurries are the same; or different, the method of clause 338 or 339, further comprising forming.

Article 341. 341. The method of any one of clauses 328-340, wherein at least one of the first slurry, the second slurry and/or the third slurry contains boric acid.

Article 342. 342. The method of clause 341, wherein the boric acid is in an amount from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco.

Article 343. At least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco 343. A method according to any one of clauses 328 to 342, containing a clay, such as a kaolin clay, in an amount of %.

Article 344. 343. The method of any one of clauses 311-343, wherein the board comprises holes in the back cover sheet; and a back cover sheet in the form of superabsorbent paper.

Article 345. Clause 311, wherein the board comprises holes in the back cover sheet; and starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. 343. The method of any one of paragraphs 1-343.

Article 346. the board defining holes in the back cover sheet; and (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being a second slurry comprising water, stucco, and skim coat starch. wherein the first side of the back skim coat faces the back cover sheet and the second side of the back ski coat faces the first core side; and (ii) A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and optionally skim coat starch; a top skim coat layer with one side facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, the skim coat starch covering the core 343. The method of any one of clauses 311-343, wherein the second and third slurries may be the same or different, enhancing the bond between the and at least the back cover sheet.

Article 347. and a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. 343. The method of any one of clauses 311-343, comprising

Article 348. The board is a back cover sheet in the form of a super absorbent paper; and (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch. a back skim coat layer formed from a second slurry, the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and optionally skim coat starch, a front skim coat layer, the first side of the skim coat layer facing the second side of the board core and the second side of the front skim coat layer facing the front cover sheet, the skim coat 344.The method of any one of clauses 311-343, wherein the starch enhances the bond between the core and at least the back coversheet, and the second and third slurries may be the same or different.

Article 349. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; and (i) first and second skim coats; A back skim coat layer defining a surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet. a back skim coat layer, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a top skim coat layer, the second side of the layer facing the top cover sheet, the skim coat starch reinforcing the bond between the core and at least the back cover sheet; 343. The method of any one of clauses 311-343, wherein the slurries may be the same or different.

Clause 350. a back cover sheet in the form of superabsorbent paper; and between at least one of the set gypsum core and the cover sheet, preferably at least between the back cover sheet and the set gypsum core. 343. The method of any one of clauses 311-343, comprising the included starch.

Article 351. The board comprises holes in the back cover sheet; the back cover sheet is in the form of an absorbent paper; and (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco and a second slurry comprising skim coat starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and optionally skim coat starch. with the first side of the front skim coat layer facing the second side of the board core and the second side of the front skim coat layer facing the front cover sheet. a layer, wherein the skim-coated starch enhances the bond between the core and at least the backing coversheet, and the second and third slurries may be the same or different; The method described in section.

Article 352. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; A back skim coat layer defining first and second skim coat surfaces, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat being the back skim coat layer; a back skim coat layer facing the cover sheet and the second side of the back ski coat facing the first core side; and (ii) a front skim coat layer defining the first and second sides. wherein a top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core; a top skim coat layer with a second side of the top skim coat layer facing the top cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; 343. The method of any one of clauses 311-343, wherein the second and third slurries may be the same or different.

Article 353. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; and (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; defining a back skim coat layer, the side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; a top skim coat layer, the top skim coat layer being formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer being the second surface of the board core; and a second side of the top skim coat layer facing the top cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet and the second and third slurries may be the same or different.

Article 354. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side of the skim coat facing the back coversheet and the second side of the back skim coat facing the first core side, and (ii) first and second A front skim coat layer defining a surface of the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, the first surface of the front skim coat layer comprising: a top skim coat layer facing the second side of the board core, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch covering the core and at least the back cover sheet; and the second and third slurries may be the same or different; and, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 343. The method of any one of clauses 311-343, comprising boric acid in an amount of 0.05% to about 0.3% by weight.

Article 355. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side of the skim coat facing the back coversheet and the second side of the back skim coat facing the first core side, and (ii) first and second A front skim coat layer defining a surface of the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, the first surface of the front skim coat layer comprising: a top skim coat layer facing the second side of the board core, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch covering the core and at least the back cover sheet; and the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, about 1 part of stucco. 343. A method according to any one of clauses 311 to 343, containing clay, eg kaolin clay, in an amount of from about 1% to about 10% by weight, eg from about 1% to about 5% by weight of the stucco.

Article 356. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side of the skim coat facing the back coversheet and the second side of the back skim coat facing the first core side, and (ii) first and second A front skim coat layer defining a surface of the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, the first surface of the front skim coat layer comprising: a top skim coat layer facing the second side of the board core, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch covering the core and at least the back cover sheet; and the second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1 weight of stucco; % to about 10% by weight, such as from about 1% to about 5% by weight of the stucco; the first slurry, the second slurry, and/or the third slurry. contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. or the method described in paragraph 1.

Article 357. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side of the skim coat facing the back coversheet and the second side of the back skim coat facing the first core side, and (ii) first and second A front skim coat layer defining a surface of the front skim coat layer is formed from a third slurry comprising water, stucco, and, optionally, skim coat starch, the first surface of the front skim coat layer comprising: a top skim coat layer facing the second side of the board core, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch covering the core and at least the back cover sheet; and the second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1 weight of stucco; % to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 343. The method of any one of clauses 311-343, wherein at least one of the slurries contains polyphosphate.

Article 358. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. and boric acid in an amount of, for example, from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. 343. The method of any one of paragraphs 311-343.

Article 359. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. for example, from about 0.01% to about 0.5% by weight of the stucco, for example from about 0.05% to about 0.3% by weight of the stucco; At least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco 343. The method of any one of clauses 311-343, containing an amount of clay, such as kaolin clay.

Article 360. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. for example, from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; at least one of the slurry of, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate. The method according to item 1.

Article 361. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. for example, from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; at least one of the slurry of, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second and/or at least one of the third slurry contains a retardant.

Article 362. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. for example, from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; at least one of the slurry of, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The method according to item 1.

Article 363. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. for example, from about 0.01% to about 0.5% by weight of the stucco, for example from about 0.05% to about 0.3% by weight of the stucco; 344. The method of any one of clauses 311-343, wherein at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate.

Article 364. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. for example, from about 0.01% to about 0.5% by weight of the stucco, for example from about 0.05% to about 0.3% by weight of the stucco; 344. The method of any one of clauses 311-343, wherein at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Article 365. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, about 1% to about 10% by weight of the stucco, such as 343. The method of any one of clauses 311-343, containing a clay, such as a kaolin clay, in an amount of about 1% to about 5% by weight.

Article 366. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% to about 10% by weight of the stucco, such as about a clay, such as a kaolin clay, in an amount of 1% to about 5% by weight; and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate. 343. The method of any one of clauses 311-343.

Article 367. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% to about 10% by weight of the stucco, such as about clay, such as kaolin clay, in an amount from 1% to about 5% by weight; at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Article 368. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% to about 10% by weight of the stucco, such as about clay, such as kaolin clay, in an amount from 1% to about 5% by weight; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retarder. 343. The method of any one of clauses 311-343.

Article 369. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. Method.

Article 370. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second slurry, and/or Or the method of any one of clauses 311-343, wherein at least one of the third slurries contains a retardant.

Article 371. A board includes holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core. and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. Method.

Article 372. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch strengthens the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and, for example, about 0.01 weight of stucco % to about 0.5%, such as from about 0.05% to about 0.3% by weight of the stucco.

Article 373. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; boric acid in an amount of from to about 0.5%, for example from about 0.05% to about 0.3% by weight of the stucco; Clause 311, wherein at least one of the slurries contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 343. The method of any one of paragraphs 1-343.

Article 374. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; the first slurry, the second slurry, and/or the third slurry comprises boric acid in an amount of to about 0.5%, for example, from about 0.05% to about 0.3% by weight of the stucco; at least one of which contains a clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; at least one of the slurry, the second slurry, and/or the third slurry contains polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry 343. The method of any one of clauses 311-343, wherein one contains a retardant.

Article 375. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; the first slurry, the second slurry, and/or the third slurry comprises boric acid in an amount of to about 0.5%, for example, from about 0.05% to about 0.3% by weight of the stucco; at least one of which contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 344. The method of any one of clauses 311-343, wherein at least one of the slurry of, the second slurry, and/or the third slurry contains polyphosphate.

Article 376. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; the first slurry, the second slurry, and/or the third slurry comprises boric acid in an amount of to about 0.5%, for example, from about 0.05% to about 0.3% by weight of the stucco; at least one of which contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 344. The method of any one of clauses 311-343, wherein at least one of the slurry of, the second slurry, and/or the third slurry contains a retardant.

Article 377. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch strengthens the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; boric acid in an amount of from to about 0.5%, for example from about 0.05% to about 0.3% by weight of the stucco; 343. The method of any one of clauses 311-343, wherein at least one of the slurries contains polyphosphate.

Article 378. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch strengthens the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; comprising boric acid in an amount of to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. or the method described in paragraph 1.

Article 379. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch strengthens the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; boric acid in an amount of from to about 0.5%, for example from about 0.05% to about 0.3% by weight of the stucco; 343. The method of any one of clauses 311-343, wherein at least one of the slurries contains a retardant.

Article 380. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and the first slurry, the second slurry and/or at least one of the third slurries comprises a clay, such as kaolin, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. 343. The method of any one of clauses 311-343, comprising clay.

Article 381. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; the first slurry, the second slurry, and/or at least one of the third slurries is clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate.

Article 382. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; the first slurry, the second slurry, and/or at least one of the third slurries is clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second slurry, and/or the third contains a retardant.

Article 383. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; the first slurry, the second slurry, and/or at least one of the third slurries is clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Article 384. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and the first slurry, the second slurry , and/or at least one of the third slurries contains a polyphosphate.

Article 385. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; the first slurry, the second slurry, and/or at least one of the third slurries contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. , Clauses 311-343.

Article 386. a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and Formed from a second slurry comprising skim-coated starch, the first side of the back skim coat facing the back cover sheet and the second side of the back ski coat facing the first core side. , a back skim coat layer, and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer comprising water, stucco, and, optionally, skim coat starch. wherein the first side of the top skim coat layer faces the second side of the board core and the second side of the top skim coat layer faces the top cover sheet; wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and the first slurry, the second slurry , and/or at least one of the third slurries contains a retardant.

Article 387. a backing coversheet in the form of superabsorbent paper; and, for example, from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.05% by weight of stucco. 343. The method of any one of clauses 311-343, comprising boric acid in an amount of 0.3% by weight.

Article 388. back cover sheet in the form of superabsorbent paper; for example from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0% by weight of stucco; and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco. 343. A method according to any one of clauses 311 to 343, comprising clay, eg kaolin clay, in an amount of, eg, about 1% to about 5% by weight of the stucco.

Article 389. back cover sheet in the form of superabsorbent paper; for example from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0% by weight of stucco; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco; For example, contains a clay, such as a kaolin clay, in an amount of about 1% to about 5% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry , containing polyphosphate.

Article 390. back cover sheet in the form of superabsorbent paper; for example from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0% by weight of stucco; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco; For example, contains a clay, such as a kaolin clay, in an amount of about 1% to about 5% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry , containing a retardant.

Article 391. back cover sheet in the form of superabsorbent paper; for example from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0% by weight of stucco; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. The method according to item 1.

Article 392. back cover sheet in the form of superabsorbent paper; for example from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0% by weight of stucco; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and/or at least one of the third slurry contains a retardant.

Article 393. back cover sheet in the form of superabsorbent paper; for example from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0% by weight of stucco; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The method according to item 1.

Article 394. a back cover sheet in the form of superabsorbent paper; 343. A method according to any one of clauses 311 to 343, containing the clay, eg kaolin clay, in an amount of about 1% to about 10%, eg about 1% to about 5% by weight of the stucco.

Article 395. a board comprising holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; a clay, such as a kaolin clay, in an amount of 1% to about 10%, for example, about 1% to about 5% by weight of the stucco; 343. The method of any one of clauses 311-343, wherein at least one of the slurries of 3 contains polyphosphate.

Article 396. a board comprising holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; containing clay, such as kaolin clay, in an amount of 1% to about 10%, eg, about 1% to about 5%, by weight of the stucco; the first slurry, the second slurry, and/or the third contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The method according to any one of .

Article 397. a board comprising holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; a clay, such as a kaolin clay, in an amount of 1% to about 10%, for example, about 1% to about 5% by weight of the stucco; 343. The method of any one of clauses 311-343, wherein at least one of the slurries of 3 contains a retardant.

Article 398. a board comprising holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; and at least one of the first slurry, the second slurry, and/or the third slurry containing polyphosphate. , Clauses 311-343.

Article 399. a board comprising holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; and at least one of the first slurry, the second slurry and/or the third slurry containing polyphosphate. and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Clause 400. a board comprising holes in the back cover sheet; a back cover sheet in the form of superabsorbent paper; and at least one of the first slurry, the second slurry, and/or the third slurry containing a retardant. 343. The method of any one of clauses 311-343.

Clause 401. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries may be the same or different; and, for example, from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco. 343. The method of any one of clauses 311-343, comprising boric acid in an amount of % by weight.

Clause 402. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; % boric acid; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco, for example, 343. A method according to any one of clauses 311 to 343, containing a clay, such as a kaolin clay, in an amount of about 1% to about 5% by weight of the stucco.

Clause 403. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; % boric acid; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco, e.g. at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate in an amount of about 1% to about 5% by weight of the and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Clause 404. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; % boric acid; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco, e.g. and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate in an amount of from about 1% to about 5% by weight of the 343. The method of any one of clauses 311-343, comprising

Clause 405. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; % boric acid; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco, e.g. and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant 343. The method of any one of clauses 311-343, comprising

Article 406. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; % boric acid; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. described method.

Article 407. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; % amount of boric acid; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, the second slurry, and/or at least one of the third slurries contains a retardant.

Clause 408. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; % boric acid; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. described method.

Article 409. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; the second and third slurries may be the same or different; 343. A method according to any one of clauses 311 to 343, containing the clay, eg kaolin clay, in an amount of about 10%, eg about 1% to about 5% by weight of the stucco.

Clause 410. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; 10% by weight, such as from about 1% to about 5% by weight of the stucco, containing a clay, such as a kaolin clay; and of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate.

Article 411. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; of the first slurry, the second slurry, and/or the third slurry any one of clauses 311-343, wherein at least one contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant The method described in .

Article 412. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The two and third slurries can be the same or different; 10% by weight, such as from about 1% to about 5% by weight of the stucco, containing a clay, such as a kaolin clay; and of the first slurry, the second slurry, and/or the third slurry contains a retarding agent.

Article 413. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; clauses 311-, wherein the second and third slurries may be the same or different; and at least one of the first, second, and/or third slurry contains polyphosphate 343. The method of any one of clauses 343 to 343.

Article 414. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; The second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; 344. The method of any one of clauses 311-343, wherein at least one of the slurry, the second slurry and/or the third slurry contains a retardant.

Article 415. starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core; (i) a first and a back skim coat layer defining a second skim coat surface, the back ski coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first surface of the back ski coat being the back cover a back skim coat layer facing the sheet, the second side of the back ski coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides; Then, a top skimcoat layer is formed from a third slurry comprising water, stucco, and optionally skimcoat starch, the first side of the top skimcoat layer facing the second side of the board core. a top skim coat layer, the second side of the top skim coat layer facing the top cover sheet, the skim coat starch enhancing the bond between the core and at least the back cover sheet; Clauses 311-, wherein the two and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. 343. The method of any one of clauses 343 to 343.

Article 416. starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; and, for example, stucco. Clause 311-343, comprising boric acid in an amount of from about 0.01% to about 0.5%, for example from about 0.05% to about 0.3% by weight of the stucco the method of.

Article 417. The board contains holes in the back cover sheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; boric acid in an amount of 0.01% to about 0.5%, for example, about 0.05% to about 0.3% by weight of the stucco; and the first slurry, the second slurry, and /or at least one of the third slurries comprises clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 343. The method of any one of clauses 311-343, comprising:

Article 418. starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; the first slurry, the second slurry, and/or or at least one of the third slurries contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate.

Article 419. starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; the first slurry, the second slurry, and/or or at least one of the third slurries contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Clause 420. starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; boric acid in an amount of 0.01% to about 0.5%, for example, about 0.05% to about 0.3% by weight of the stucco; and the first slurry, the second slurry, and /or The method of any one of clauses 311-343, wherein at least one of the third slurries contains polyphosphate.

Article 421. starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; the first slurry, the second slurry, and/or or at least one of the third slurries contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. 343. The method of any one of paragraphs 311-343.

Article 422. starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; boric acid in an amount of 0.01% to about 0.5%, for example, about 0.05% to about 0.3% by weight of the stucco; and the first slurry, the second slurry, and /or The method of any one of clauses 311-343, wherein at least one of the third slurries contains a retardant.

Article 423. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; and a first at least one of the slurry of, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. 343. The method of any one of clauses 311-343, containing an amount of clay, such as kaolin clay.

Article 424. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; At least one of the slurry, the second slurry, and/or the third slurry in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco clay, such as kaolin clay; and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate. The method described in section.

Article 425. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; At least one of the slurry, the second slurry, and/or the third slurry in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second 343. The method of any one of clauses 311-343, wherein at least one of the slurry and/or the third slurry contains a retardant.

Article 426. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; At least one of the slurry, the second slurry, and/or the third slurry in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The method described in section.

Article 427. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; and a first 344. The method of any one of clauses 311-343, wherein at least one of the slurry of, the second slurry, and/or the third slurry contains polyphosphate.

Article 428. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; at least one of the slurry, the second slurry, and/or the third slurry contains polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry 343. The method of any one of clauses 311-343, wherein one contains a retardant.

Article 429. a board comprising holes in the back coversheet; starch contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; and a first 344. The method of any one of clauses 311-343, wherein at least one of the slurry of, the second slurry, and/or the third slurry contains a retardant.

Article 430. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and The second and third slurries may be the same or different; and for example from about 0.01% to about 0.5% by weight of the stucco, such as 343, comprising boric acid in an amount of from about 0.05% to about 0.3% by weight of the stucco.

Article 431. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and Strengthening the bond between at least the back cover sheet, the second and third slurries may be the same or different; boric acid in an amount of about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry, for example, Clause 311-343, containing a clay, such as a kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. Method.

Article 432. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and Strengthening the bond between at least the back cover sheet, the second and third slurries may be the same or different; boric acid in an amount of about 0.05% to about 0.3% by weight of the stucco; clay, such as kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; and the first slurry, the second slurry, and/or Or the method of any one of clauses 311-343, wherein at least one of the third slurries contains polyphosphate.

Article 433. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and Strengthening the bond between at least the back cover sheet, the second and third slurries may be the same or different; boric acid in an amount of about 0.05% to about 0.3% by weight of the stucco; clay, such as kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; and the first slurry, the second slurry, and/or Or the method of any one of clauses 311-343, wherein at least one of the third slurries contains a retardant.

Article 434. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and Strengthening the bond between at least the back cover sheet, the second and third slurries may be the same or different; boric acid in an amount of about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry comprises polyphosphate 343. The method of any one of clauses 311-343, comprising

Article 435. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and Strengthening the bond between at least the back cover sheet, the second and third slurries may be the same or different; boric acid in an amount of about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry comprises polyphosphate. and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Article 436. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and Strengthening the bond between at least the back cover sheet, the second and third slurries may be the same or different; boric acid in an amount of about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry comprises a retardant 343. The method of any one of clauses 311-343, comprising

Article 437. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet, the second and third slurries may be the same or different; contains clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. A method according to any one of paragraphs.

Article 438. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet and the second and third slurries may be the same or different; at least one containing a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 344. The method of any one of clauses 311-343, wherein at least one of the second slurry and/or the third slurry contains polyphosphate.

Article 439. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet and the second and third slurries may be the same or different; at least one containing a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; at least one of the second slurry, and/or the third slurry contains polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardation 343. The method of any one of clauses 311-343, comprising an agent.

Article 440. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet and the second and third slurries may be the same or different; at least one containing a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 344. The method of any one of clauses 311-343, wherein at least one of the second slurry and/or the third slurry contains a retardant.

Article 441. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet, the second and third slurries may be the same or different; contains a polyphosphate.

Article 442. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet and the second and third slurries may be the same or different; any one of clauses 311-343, wherein at least one contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant The method described in .

Article 443. (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer formed with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a second A front skim coat layer defining first and second surfaces, the front skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a face skim coat layer facing the second face of the board core and the second face of the face skim coat layer facing the face cover sheet, wherein the skim coat starch comprises the core and strengthens the bond between at least the back cover sheet, the second and third slurries may be the same or different; contains a retarding agent.

Article 444. and boric acid in an amount such as from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. 343. The method of any one of clauses 311-343, comprising

Article 445. The board contains holes in the back cover sheet; for example boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 1% by weight of the stucco 343. A method according to any one of clauses 311 to 343, containing clay, eg kaolin clay, in an amount of about 5% by weight.

Article 446. The board is provided with holes in the back cover sheet; for example boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about clauses 311-, wherein at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; 343. The method of any one of clauses 343 to 343.

Article 447. The board contains holes in the back cover sheet; for example boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about clauses 311-, wherein at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant, containing a clay, such as a kaolin clay, in an amount of 5% by weight; 343. The method of any one of clauses 343 to 343.

Article 448. The board is provided with holes in the back cover sheet; for example boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate.

Article 449. The board is provided with holes in the back cover sheet; for example boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, the second slurry, and/or the third slurry contains a retardant.

Clause 450. The board contains holes in the back cover sheet; for example boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Article 451. the board includes holes in the back cover sheet; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco; 343. The method of any one of clauses 311-343, comprising a clay, such as a kaolin clay, in an amount of, for example, about 1% to about 5% by weight of the stucco.

Article 452. The board includes holes in the back cover sheet; , a clay, such as a kaolin clay, in an amount of about 1% to about 5% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry, 343. The method of any one of clauses 311-343, containing polyphosphate.

Article 453. The board includes holes in the back cover sheet; at least one of the first slurry, the second slurry, and/or the third slurry contains a poly 344. The method of any one of clauses 311-343, wherein at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Article 454. any one of clauses 311-343, wherein the board includes holes in the back cover sheet; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. The method described in section.

Article 455. at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, the second 343. The method of any one of clauses 311-343, wherein at least one of the slurry and/or the third slurry contains a retardant.

Article 456. any one of clauses 311-343, wherein the board includes holes in the back cover sheet; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The method described in section.

Article 457. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; reinforcing, the second and third slurries may be the same or different; 343. The method of any one of clauses 311-343, comprising boric acid in an amount of about 0.3% by weight.

Article 458. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains, for example, from about 1% to about 10% by weight of the stucco. %, eg, from about 1% to about 5% by weight of the stucco.

Article 459. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; including boric acid in an amount of 0.3% by weight; at least one of the first slurry, the second slurry, and/or the third slurry, for example, from about 1% to about 10% by weight of the stucco at least one of the first slurry, the second slurry, and/or the third slurry contains a clay, such as a kaolin clay, in an amount of, for example, about 1% to about 5% by weight of the stucco; , contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. Method.

Article 460. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; including boric acid in an amount of 0.3% by weight; at least one of the first slurry, the second slurry, and/or the third slurry, for example, from about 1% to about 10% by weight of the stucco , e.g., a clay, e.g., kaolin clay, in an amount of from about 1% to about 5% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry. 343. The method of any one of clauses 311-343, wherein one contains a polyphosphate.

Article 461. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; including boric acid in an amount of 0.3% by weight; at least one of the first slurry, the second slurry, and/or the third slurry, for example, from about 1% to about 10% by weight of the stucco , e.g., a clay, e.g., kaolin clay, in an amount of from about 1% to about 5% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry. 343. The method of any one of clauses 311-343, wherein one contains a retardant.

Article 462. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. or the method described in paragraph 1.

Article 463. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, the first 344. The method of any one of clauses 311-343, wherein at least one of the second slurry and/or the third slurry contains a retardant.

Article 464. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; any of clauses 311-343, comprising boric acid in an amount of 0.3% by weight; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. or the method described in paragraph 1.

Article 465. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; reinforcing, the second and third slurries may be the same or different; 343. A method according to any one of clauses 311 to 343, containing the clay, eg kaolin clay, in an amount of 1% to about 10%, eg about 1% to about 5% by weight of the stucco.

Article 466. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; % to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; contains polyphosphate.

Article 467. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; % to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; of clauses 311-343, wherein at least one of the slurries contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. A method according to any one of paragraphs.

Article 468. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; Strengthening, the second and third slurries may be the same or different; % to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; contains a retardant.

Article 469. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; reinforcing, the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate , Clauses 311-343.

Article 470. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; reinforcing, the second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and at least one of the first slurry, the second slurry and/or the third slurry contains a retardant.

Article 471. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back skim coat; faces the back cover sheet and the second side of the back skim coat faces the first core side; and (ii) a surface defining the first and second sides; A skim coat layer, wherein the top skim coat layer is formed from a third slurry comprising water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second surface of the board core; a face skim coat layer facing the face, the second side of the face skim coat layer facing the face cover sheet, the skim coat starch providing bonding between the core and at least the back cover sheet; strengthen, the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant , Clauses 311-343.

Article 472. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; and Any of clauses 311-343, including boric acid in an amount of, for example, from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco The method according to item 1.

Article 473. a backing coversheet in which the board is in the form of a super absorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing cover sheet and the set gypsum core; , boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; and/or at least one of the third slurry contains clay, e.g. , kaolin clay.

Article 474. a backing coversheet in which the board is in the form of a super absorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing cover sheet and the set gypsum core; , boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; At least one of the slurry and/or the third slurry contains clay, e.g., in an amount of from about 1% to about 10% by weight of the stucco, e.g. 344. The method of any one of clauses 311-343, comprising kaolin clay; and at least one of the first slurry, second slurry, and/or third slurry comprising polyphosphate. .

Article 475. a backing coversheet in which the board is in the form of a super absorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing cover sheet and the set gypsum core; , boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; At least one of the slurry and/or the third slurry contains clay, e.g., in an amount of from about 1% to about 10% by weight of the stucco, e.g. 344. The method of any one of clauses 311-343, wherein the kaolin clay is contained; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. .

Article 476. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; , boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; and/or at least one of the third slurry contains polyphosphate.

Article 477. The board has a backing coversheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the backing coversheet and the set gypsum core; , boric acid in an amount of from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco; and/or at least one of the third slurry contains a retardant.

Article 478. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 343. A method according to any one of clauses 311 to 343, containing clay, eg kaolin clay, in an amount of 5% by weight.

Article 479. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; Clauses 311-343, containing a clay, such as a kaolin clay, in an amount of weight percent; and at least one of the first slurry, the second slurry, and/or the third slurry containing a polyphosphate. The method according to any one of .

Article 480. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry. 344. The method of any one of clauses 311-343, wherein at least one of the , second slurry, and/or third slurry contains a retardant.

Article 481. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; Clauses 311-343, containing a clay, such as a kaolin clay, in an amount of weight percent; and at least one of the first slurry, the second slurry, and/or the third slurry containing a retardant. The method according to any one of .

Article 482. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate.

Article 483. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, the second slurry, and/or the third slurry 343. The method of any one of clauses 311-343, at least one of which contains a retardant.

Article 484. The board comprises a backing cover sheet in the form of a superabsorbent paper; a starch contained between at least one of the set gypsum core and the set gypsum core, preferably at least between the back cover sheet and the set gypsum core. and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Article 485. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; 343. The method of any one of clauses 311-343, comprising boric acid in an amount of weight percent, such as from about 0.05 weight percent to about 0.3 weight percent of the stucco.

Article 486. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; %, for example, from about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry. 343. Any one of clauses 311-343, wherein the clay, e.g., kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, e.g., from about 1% to about 5% by weight of the stucco. The method described in section.

Article 487. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; %, for example, from about 0.05% to about 0.3% by weight of the stucco; at least one of the first slurry, the second slurry, and/or the third slurry comprises a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 343. The method of any one of clauses 311-343, wherein at least one of the slurry and/or the third slurry contains polyphosphate.

Article 488. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; %, for example, from about 0.05% to about 0.3% by weight of the stucco; at least one of the first slurry, the second slurry, and/or the third slurry comprises a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 344. The method of any one of clauses 311-343, wherein at least one of the slurry and/or the third slurry contains a retardant.

Article 489. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; %, for example, from about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry. 343. The method of any one of clauses 311-343, wherein one contains a polyphosphate.

Article 490. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; %, for example, from about 0.05% to about 0.3% by weight of the stucco; at least one of the first slurry, the second slurry, and/or the third slurry comprises , contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. Method.

Article 491. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; %, for example, from about 0.05% to about 0.3% by weight of the stucco; and at least one of the first slurry, the second slurry, and/or the third slurry. 343. The method of any one of clauses 311-343, wherein one contains a retardant.

Article 492. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and the first slurry, the second slurry, and/or the third contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. 343. The method of any one of paragraphs 311-343.

Article 493. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; at least one of the slurries contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 344. The method of any one of clauses 311-343, wherein at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate.

Article 494. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; at least one of the slurries contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry 343. The method of any one of clauses 311-343, one of which contains a retardant.

Article 495. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; at least one of the slurries contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 344. The method of any one of clauses 311-343, wherein at least one of the first slurry, the second slurry and/or the third slurry contains a retardant.

Article 496. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and the first slurry, the second slurry, and/or the third contains polyphosphate.

Article 497. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, and the second and third slurries may be the same or different; of clauses 311-343, wherein at least one of the slurries contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. A method according to any one of paragraphs.

Article 498. The board is a back cover sheet in the form of a superabsorbent paper; (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer comprising water, stucco, and skim coat starch; a back skim coat layer formed from a slurry of 2, with the first side of the back ski coat facing the back cover sheet and the second side of the back ski coat facing the first core side; and (ii) a top skim coat layer defining first and second surfaces, the top skim coat layer being formed from a third slurry comprising water, stucco, and, optionally, skim coat starch; a top skim coat layer, the first side of the layer facing the second side of the board core and the second side of the top skim coat layer facing the top cover sheet, skim coat starch; enhances the bond between the core and at least the back cover sheet, the second and third slurries may be the same or different; and the first slurry, the second slurry, and/or the third contains a retardant.

Article 499. The board comprises a backing cover sheet in the form of super absorbent paper; 343. The method of any one of clauses 311-343, comprising an amount of boric acid.

Clause 500. The board is a backing coversheet in the form of a superabsorbent paper; for example, in an amount of from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% to about 10% by weight of the stucco, such as about 343. The method of any one of clauses 311-343, containing clay, such as kaolin clay, in an amount from 1% to about 5% by weight.

Clause 501. The board is a backing coversheet in the form of a superabsorbent paper; for example, in an amount of from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco of boric acid; a clay, such as a kaolin clay, in an amount from about 5% by weight to about 5% by weight; and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate. , Clauses 311-343.

Clause 502. The board is a backing coversheet in the form of a superabsorbent paper; for example, in an amount of from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco of boric acid; a clay, such as a kaolin clay, in an amount from weight percent to about 5 weight percent; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. , Clauses 311-343.

Clause 503. The board is a backing coversheet in the form of a superabsorbent paper; for example, in an amount of from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate. .

Clause 504. The board is a backing coversheet in the form of super absorbent paper; for example, in an amount of from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second slurry, and/or 343. The method of any one of clauses 311-343, wherein at least one of the third slurries contains a retardant.

Clause 505. The board is a backing coversheet in the form of a superabsorbent paper; for example, in an amount of from about 0.01% to about 0.5% by weight of stucco, such as from about 0.05% to about 0.3% by weight of stucco and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. .

Article 506. and at least one of the first slurry, second slurry, and/or third slurry comprises, for example, from about 1% by weight of stucco to about 343. A method according to any one of clauses 311 to 343, containing the clay, eg kaolin clay, in an amount of 10% by weight, eg from about 1% to about 5% by weight of the stucco.

Article 507. The board includes a back cover sheet in the form of superabsorbent paper; %, for example, from about 1% to about 5% by weight of the stucco; and of the first slurry, the second slurry, and/or the third slurry. 343. The method of any one of clauses 311-343, wherein at least one contains a polyphosphate.

Article 508. The board includes a back cover sheet in the form of superabsorbent paper; %, for example, from about 1% to about 5% by weight of the stucco; 344. Any one of clauses 311-343, wherein one contains the polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. described method.

Article 509. The board includes a back cover sheet in the form of superabsorbent paper; %, for example, from about 1% to about 5% by weight of the stucco; and of the first slurry, the second slurry, and/or the third slurry. 343. The method of any one of clauses 311-343, wherein at least one contains a retardant.

Article 510. of clauses 311-343, wherein the board includes a back cover sheet in the form of superabsorbent paper; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. A method according to any one of paragraphs.

Article 511. The board includes a back cover sheet in the form of superabsorbent paper; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry , the second slurry, and/or the third slurry contains a retardant.

Article 512. Clauses 311-343, wherein the board includes a back cover sheet in the form of superabsorbent paper; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The method according to any one of .

Article 513. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; may be the same or different; and boron in an amount of, for example, from about 0.01% to about 0.5% by weight of the stucco, such as from about 0.05% to about 0.3% by weight of the stucco. 343. The method of any one of clauses 311-343, comprising an acid.

Article 514. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% to about 10% by weight of the stucco, such as about 1% by weight of the stucco 343. The method of any one of clauses 311-343, containing a clay, such as a kaolin clay, in an amount of to about 5% by weight.

Article 515. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 1% by weight of the stucco Clause 311, containing a clay, such as a kaolin clay, in an amount of about 5% by weight; and at least one of the first slurry, the second slurry, and/or the third slurry containing a polyphosphate. 343. The method of any one of paragraphs 1-343.

Article 516. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 1% by weight of the stucco Clause 311, wherein the clay, e.g., kaolin clay, in an amount of about 5% by weight; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. 343. The method of any one of paragraphs 1-343.

Article 517. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate.

Article 518. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, the second slurry, and/or the third 343. The method of any one of clauses 311-343, wherein at least one of the slurries contains a retardant.

Article 519. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Article 520. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% to about 10% by weight of the stucco, such as 343. The method of any one of clauses 311 to 343, containing a clay, such as a kaolin clay, in an amount of from about 1% to about 5% by weight of the stucco.

Article 521. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; clay, such as kaolin clay, in an amount of about 1% to about 5% by weight of the stucco; 343. The method of any one of clauses 311-343, containing phosphate.

Article 522. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; can be the same or different; clay, such as kaolin clay, in an amount of from about 1% to about 5% by weight of the stucco; at least one of the first slurry, the second slurry, and/or the third slurry comprises a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Article 523. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate. The method described in .

Article 524. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second slurry , and/or at least one of the third slurries contains a retardant.

Article 525. a starch board contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; (i) first and second skim-coated surfaces; wherein the back skim coat layer is formed from a second slurry comprising water, stucco, and skim coat starch, the first side of the back ski coat facing the back cover sheet , a back skim coat layer, the second side of the back skim coat facing the first core side, and (ii) a front skim coat layer defining the first and second sides, the front skim coat layer comprising , water, stucco, and optionally skim coat starch, the first side of the top skim coat layer facing the second side of the board core, the top skim coat layer a front skim coat layer facing the front cover sheet, wherein the skim coat starch enhances the bond between the core and at least the back cover sheet; the second and third slurries; may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. The method described in .

Article 526. starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; and, for example, about 0.01% by weight of the stucco. 343. The method of any one of clauses 311-343, comprising boric acid in an amount of to about 0.5% by weight, such as from about 0.05% to about 0.3% by weight of the stucco.

Article 527. starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; for example, from about 0.01% by weight of stucco; boric acid in an amount of about 0.5% by weight, such as from about 0.05% to about 0.3% by weight of the stucco; and the first slurry, the second slurry, and/or the third slurry. contains clay, such as kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. 343. The method of any one of clauses 343 to 343.

Article 528. starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; for example, from about 0.01% by weight of stucco; of the first slurry, the second slurry, and/or the third slurry; at least one of which contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 344. The method of any one of clauses 311-343, wherein at least one of the slurry, the second slurry, and/or the third slurry contains polyphosphate.

Article 529. starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; for example, from about 0.01% by weight of stucco; of the first slurry, the second slurry, and/or the third slurry; at least one of which contains a clay, such as a kaolin clay, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; 344. The method of any one of clauses 311-343, wherein at least one of the slurry, the second slurry and/or the third slurry contains a retardant.

Article 530. starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; for example, from about 0.01% by weight of stucco; boric acid in an amount of about 0.5% by weight, such as from about 0.05% to about 0.3% by weight of the stucco; and the first slurry, the second slurry, and/or the third slurry. contains a polyphosphate.

Article 531. starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; for example, from about 0.01% by weight of stucco; of the first slurry, the second slurry, and/or the third slurry; any of clauses 311-343, at least one of which contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant The method according to item 1.

Article 532. starch in which the board is contained between the set gypsum core and at least one of the cover sheets, preferably at least between the back cover sheet and the set gypsum core; for example, from about 0.01% by weight of stucco; boric acid in an amount of about 0.5% by weight, such as from about 0.05% to about 0.3% by weight of the stucco; and the first slurry, the second slurry, and/or the third slurry. contains a retardant.

Article 533. The board comprises starch contained between at least one of the set gypsum core and the cover sheet, preferably at least between the back cover sheet and the set gypsum core; At least one of the slurry and/or the third slurry contains clay, e.g. 343. The method of any one of clauses 311-343, comprising kaolin clay.

Article 534. The board comprises starch contained between at least one of the set gypsum core and the cover sheets, preferably at least between the back cover sheet and the set gypsum core; first slurry, second slurry and/or at least one of the third slurries comprises a clay, such as kaolin, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. 344. The method of any one of clauses 311-343, wherein at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate.

Article 535. The board comprises starch contained between at least one of the set gypsum core and the cover sheets, preferably at least between the back cover sheet and the set gypsum core; first slurry, second slurry and/or at least one of the third slurries comprises a clay, such as kaolin, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; and the first slurry, the second slurry, and/or the third 343. The method of any one of clauses 311-343, wherein at least one of the slurries of 3 contains a retardant.

Article 536. The board comprises starch contained between at least one of the set gypsum core and the cover sheets, preferably at least between the back cover sheet and the set gypsum core; first slurry, second slurry and/or at least one of the third slurries comprises a clay, such as kaolin, in an amount of, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. 344. The method of any one of clauses 311-343, wherein at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Article 537. The board comprises starch contained between at least one of the set gypsum core and the cover sheet, preferably at least between the back cover sheet and the set gypsum core; 343. The method of any one of clauses 311-343, wherein at least one of the slurry and/or the third slurry contains polyphosphate.

Article 538. The board comprises starch contained between at least one of the set gypsum core and the cover sheets, preferably at least between the back cover sheet and the set gypsum core; first slurry, second slurry and/or at least one of the third slurry contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. 343. The method of any one of clauses 311-343.

Article 539. The board comprises starch contained between at least one of the set gypsum core and the cover sheet, preferably at least between the back cover sheet and the set gypsum core; 344. The method of any one of clauses 311-343, wherein at least one of the slurry and/or the third slurry contains a retardant.

Article 540. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet The second and third slurries may be the same or different; and for example from about 0.01% to about 0.5% by weight of the stucco, such as about 0.5% by weight of the stucco, for example about 0.5% by weight of the stucco. 343. The method of any one of clauses 311-343, comprising boric acid in an amount of 0.05% to about 0.3% by weight.

Article 541. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet to strengthen the bond between the second and third slurries, which may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% by weight of the stucco. 343. The method of any one of clauses 311-343, containing the clay, eg, kaolin clay, in an amount of from about 10%, eg, from about 1% to about 5% by weight of the stucco.

Article 542. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet to strengthen the bond between the second and third slurries, which may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 1% by weight of the stucco; a clay, such as a kaolin clay, in an amount of about 10% by weight, such as from about 1% to about 5% by weight of the stucco; and of the first slurry, the second slurry, and/or the third slurry 343. The method of any one of clauses 311-343, at least one of which contains a polyphosphate.

Article 543. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet to strengthen the bond between the second and third slurries, which may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 1% by weight of the stucco; a clay, such as a kaolin clay, in an amount of about 10% by weight, such as from about 1% to about 5% by weight of the stucco; and of the first slurry, the second slurry, and/or the third slurry 343. The method of any one of clauses 311-343, at least one of which contains a retardant.

Article 544. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet to strengthen the bond between the second and third slurries, which may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate, clause 311. 343. The method of any one of paragraphs 1-343.

Article 545. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet to strengthen the bond between the second and third slurries, which may be the same or different; % to about 0.3% by weight; at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; 344. The method of any one of clauses 311-343, wherein at least one of the slurry of, the second slurry, and/or the third slurry contains a retardant.

Article 546. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet to strengthen the bond between the second and third slurries, which may be the same or different; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant, clause 311. 343. The method of any one of paragraphs 1-343.

Article 547. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third , containing clay, such as kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco. the method of.

Article 548. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet The second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry may, for example, a clay, such as a kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; and the first slurry, the second slurry, and /or The method of any one of clauses 311-343, wherein at least one of the third slurries contains polyphosphate.

Article 549. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet The second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry may, for example, a clay, such as a kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; the first slurry, the second slurry, and/or or at least one of the third slurries contains a polyphosphate; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. 311-343.

Clause 550. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet The second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry may, for example, a clay, such as a kaolin clay, in an amount of from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco; and the first slurry, the second slurry, and /or The method of any one of clauses 311-343, wherein at least one of the third slurries contains a retardant.

Article 551. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet and the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third 343. The method of any one of clauses 311-343, containing phosphate.

Article 552. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet the second and third slurries may be the same or different; at least one of the first slurry, the second slurry, and/or the third slurry comprises polyphosphate and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant.

Article 553. A board comprises: (i) a back skim coat layer defining first and second skim coat surfaces, the back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, the first side facing the back cover sheet and the second side of the back ski coat facing the first core side, and (ii) the first and second sides; wherein the front skim coat layer is formed from a third slurry comprising water, stucco and, optionally, skim coat starch, the first side of the front skim coat layer being the board core a top skim coat layer facing the second side of the top skim coat layer, the second side of the top skim coat layer facing the top coversheet, wherein the skim coat starch is present between the core and at least the back coversheet and the second and third slurries may be the same or different; and at least one of the first slurry, the second slurry, and/or the third 343. The method of any one of clauses 311-343, comprising an agent.

Article 554. At least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 0.05% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 1% by weight of the stucco. 343. The method of any one of clauses 311-343, containing the clay, eg, kaolin clay, in an amount of from about 10%, eg, from about 1% to about 5% by weight of the stucco.

Article 555. At least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 0.05% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 1% by weight of the stucco; a clay, such as a kaolin clay, in an amount of about 10% by weight, such as from about 1% to about 5% by weight of the stucco; and of the first slurry, the second slurry, and/or the third slurry 343. The method of any one of clauses 311-343, at least one of which contains a polyphosphate.

Article 556. At least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 0.05% by weight of the stucco. at least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, from about 1% to about 1% by weight of the stucco; a clay, such as a kaolin clay, in an amount of about 10% by weight, such as from about 1% to about 5% by weight of the stucco; and of the first slurry, the second slurry, and/or the third slurry 343. The method of any one of clauses 311-343, at least one of which contains a retardant.

Article 557. At least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 0.05% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate, clause 311. 343. The method of any one of paragraphs 1-343.

Article 558. At least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 0.05% by weight of the stucco. % to about 0.3% by weight; at least one of the first slurry, the second slurry, and/or the third slurry contains a polyphosphate; 344. The method of any one of clauses 311-343, wherein at least one of the slurry of, the second slurry, and/or the third slurry contains a retardant.

Article 559. At least one of the first slurry, the second slurry, and/or the third slurry comprises, for example, about 0.01% to about 0.5% by weight of the stucco, such as about 0.05% by weight of the stucco. and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant, clause 279. 558. The method of any one of paragraphs 1-558.

Article 560. At least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco % amount of clay, e.g., kaolin clay; and at least one of a first slurry, a second slurry, and/or a third slurry; and/or at least one of the third slurries contains polyphosphate.

Article 561. At least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco % amount of clay, such as kaolin clay; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, 344. The method of any one of clauses 311-343, wherein at least one of the second slurry and/or the third slurry contains a retardant.

Article 562. At least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco % amount of clay, such as kaolin clay; at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and the first slurry, 344. The method of any one of clauses 311-343, wherein at least one of the second slurry and/or the third slurry contains a retardant.

Article 563. At least one of the first slurry, the second slurry, and/or the third slurry is, for example, from about 1% to about 10% by weight of the stucco, such as from about 1% to about 5% by weight of the stucco % amount of clay, for example, kaolin clay; and at least one of the first slurry, the second slurry, and/or the third slurry contains a retardant. A method according to any one of paragraphs.

Article 564. at least one of the first slurry, the second slurry, and/or the third slurry contains polyphosphate; and of the first slurry, the second slurry, and/or the third slurry contains a retarding agent.

Article 565. A wall system comprising a framing to which at least one gypsum board according to any one of clauses 2-278 is attached, wherein the outer surface of the front cover sheet faces away from the framing.

Article 566. A system for drying boards comprising: (a) a kiln containing at least one heat source and at least one in-kiln high frequency moisture sensor therein; (b) a controller outside the kiln; and (c) an upstream high frequency moisture content. a sensor, and an upstream dielectric sensor and a microwave sensor in communication with the controller, the upstream sensor being less susceptible to high salt concentrations in the slurry than the high frequency moisture sensor; a first upstream moisture reading; A system for generating a value and a second upstream moisture reading, respectively.

Article 567. 567. The system of clause 566, further comprising a burner power and/or air extractor associated with the kiln, the burner power and/or air extractor in communication with the controller.

Article 568. (a) a downstream high frequency moisture sensor and a downstream sensor that is less susceptible to high salt concentrations in the slurry than the high frequency moisture sensor, the downstream high frequency sensor and microwave sensor in communication with the controller; generating a first downstream moisture reading and used to bias a second upstream moisture reading; 567. The system of clause 566 or 567, which can be used to reduce the

Article 569. 569. The system of any one of clauses 566-568, wherein at least one of the sensors that are less susceptible to high salt concentrations in the slurry compared to high frequency moisture sensors is a microwave sensor.

Article 570. 569. The system of any one of clauses 566-569, wherein at least one of the high frequency sensors produces a dielectric measurement of a moisture dielectric sensor.

Article 571. 570. The system of any one of clauses 566-570, wherein the controller is a programmable logic controller.

Article 572. 572. The system of any one of clauses 566-571, wherein the kiln has one zone.

Article 573. 572. The system of any one of clauses 566-572, wherein the kiln has at least two zones.

Article 574. 573. The system of any one of clauses 566-573, wherein the kiln contains at least two in-kiln moisture sensors.

Please note that the foregoing clauses are exemplary and non-limiting. Other exemplary combinations will be apparent from the entire description herein. Those skilled in the art will also appreciate that various embodiments may be used in various combinations with other embodiments provided herein.

The following examples further illustrate the invention but should, of course, not be construed as limiting its scope in any way.

Example 1
Gypsum core (slurry) formulations containing high concentrations of various salts were prepared as specified in Table 1. Sources of chloride anions (Samples 1A-1D) were sodium chloride (NaCl), magnesium chloride (MgCl ₂ ), or calcium chloride (CaCl ₂ ). Each of Sample Nos. 1A-1D also contained sodium trimetaphosphate (TMP). Samples 1E and 1F contained TMP only in order to test the effect of TMP on insolation of other salts.

For the perforated paper sheets tested in these examples, the distance between adjacent holes was 1/4 inch. The hole diameter was about 0.01-0.02 inches.

A 12 inch by 12 inch by 1/2 inch envelope was made by using manila paper (48#/MSF) as the front coversheet and newsline paper (42lb/MSF) as the back coversheet. Prior to pouring the slurry formulation (Table 1) into the envelope, half of the Newsline paper (6″×12″) was punched using a wallboard punch as shown in FIG. The distance between adjacent holes was 1/4″. The diameter of the holes was about 0.01-0.02″.

Slurry formulations (Table 1) were prepared by dipping the dry powder into the solution for 10 seconds, mixing in a Hobart mixer for 10 seconds, followed by injecting the resulting foam for 8 seconds and mixing for an additional 2 seconds. The slurry thus obtained was poured into each envelope. After the slurry condensed and hardened, paper tape was used to seal the envelope. The sealed board was dried at 450°F for 20 minutes and then transferred to a 350°F oven. After drying at 350°F for 15 minutes, the boards were further dried at 110°F overnight.

The effect of the holes in the back cover sheet was evaluated by the "X" cut method to test the bond between the paper and the core. Several "X" cuts were made in the backing paper of the finished wallboard sample, at least two "X" cuts were made in the perforated section of the backing paper, and at least two "X" cuts were made in the backing paper. A cut was made in the imperforate section (Fig. 8). The size of the "X" cut was approximately 2 inches by 2 inches. The paper was removed from the center of the cut. By evaluating the amount of paper remaining in the gypsum core on one side of the backing paper versus the amount on the other side (i.e., perforated section versus non-perforated section), the samples were qualitatively compared to each other. evaluated to If the adhesion to the gypsum core is good, a thin layer of paper will remain on the core. In contrast, if the adhesion to the core is insufficient, the paper will detach from the core, exposing more of the core.

Figures 9-13 show photographs demonstrating the effect of various salts on adhesion in gypsum boards of the present invention with and without holes in the back cover sheet.

Figures 9-12 show photographs of sample boards 1A-1D, respectively.

FIG. 9 shows the effect of perforation on a 12″×12″×½″ sample board 1A containing 600 ppm Cl ⁻ from NaCl.

FIG. 10 shows the effect of perforation in a 12″×12″×½″ sample board 1B containing 800 ppm Cl ⁻ from NaCl.

FIG. 11 shows the effect of drilling on a 12″×12″×½″ sample board 1C containing 800 ppm Cl ⁻ from CaCl ₂ .

FIG. 12 shows the effect of drilling on a 12″×12″×½″ sample board 1D containing 800 ppm Cl ⁻ from MgCl ₂ .

Figures 9-12 show that less paper separation occurred in the perforated section of the back cover sheet compared to the non-perforated section for sample boards 1A-1D. By having less paper separation, less gypsum was exposed in the perforated section. Thus, improved board core layer adhesion was achieved in the perforated section of the back cover sheet at each concentration of all salts tested.

FIG. 13 shows perforated and 12 inch by 12 inch by 1/2 inch boards with gypsum cores made from stucco containing Cl ⁻ from 30 ppm NaCl per million parts of calcium sulfate hemihydrate. It shows the non-porous effect. This stucco represents conventional low chloride salt stucco. Experimental sample board 1E in FIG. 13 used a cover sheet with holes. Control Sample Board 1F in FIG. 13 used a cover sheet with no holes.

A comparison of experimental sample board 1E in FIG. 13 and sample board 1F in FIG. 13 shows that when low chloride was used, the holes did not improve adhesion as much as in the high chloride sample.

Example 2
Gypsum core (slurry) formulations with high chloride concentrations in the form of NaCl or MgCl ₂ were prepared as specified in Table 2. Samples indicated as containing starch in addition to _MgCl2 or NaCl refer to testing of those samples with a starch layer on the backing paper coversheet (see Table 3 below). Thus, the board cores defined by samples 1A and 2B are compositionally identical to each other, as are samples 2C and 2D. All gypsum core formulations contained a small amount of cooked corn starch.

A 12" x 12" x 1/2" envelope was made by using Manila paper (46 lb/MSF) as the front paper coversheet and Newsline paper (40 lb/MSF) as the back coversheet. . Prior to pouring the slurry formulation (Table 2) into the envelope, a diluted starch solution (Table 3) was brushed onto the core side (inside) of the backing paper cover sheets used for Samples 2B and 2D.

Slurry formulations (Table 2) were prepared by dipping the dry powder into the solution for 10 seconds, mixing in a Hobart mixer for 10 seconds, followed by injecting the resulting foam for 4.5 seconds and mixing for an additional 2 seconds. bottom. The slurry thus obtained was poured into each envelope. After the slurry condensed and hardened, paper tape was used to seal the envelope. The sealed board was dried at 450°F for 20 minutes and then transferred to a 350°F oven. After drying at 350°F for 15 minutes, the boards were further dried at 110°F overnight.

The effect of starch treatment was evaluated by the "X" cut method to test the bond between the paper and the core. Several "X" cuts were made in the backing paper of the finished wallboard samples. The size of the "X" cut was approximately 2 inches by 2 inches. The paper was removed from the center of the cut. The samples were compared to each other and evaluated qualitatively by assessing the amount of paper remaining in the gypsum core of the wallboard after stripping. If the adhesion to the gypsum core is good, a thin layer of paper will remain on the core. In contrast, if the adhesion to the core is insufficient, the paper will detach from the core, exposing more of the core.

FIG. 14 shows a photograph showing the effect of dilute starch solution on a 12″×12″×½″ board containing 1200 ppm Cl ⁻ from MgCl ₂ per million parts of calcium sulfate hemihydrate. Control Sample Board 2A had no starch layer between its paper coversheet and its gypsum core. Experimental sample board 2B had a starch layer between its paper coversheet and its gypsum core.

FIG. 15 shows a photograph showing the effect of dilute starch solution on a 12″×12″×½″ board containing 2100 ppm Cl ⁻ from MgCl ₂ per million parts of calcium sulfate hemihydrate. Control sample board 2C had no starch layer between its paper coversheet and its gypsum core. Experimental sample board 2D had a starch layer between its paper coversheet and its gypsum core.

Comparing sample boards 2A and 2B in FIG. rice field. This indicates that the starch layer significantly improved the adhesion of the paper cover sheet to the gypsum core layer made from an aqueous gypsum slurry containing 1200 ppm Cl 2 ⁻ anions.

Similarly, when comparing Samples 2C and 2D in FIG. was small. This indicates that the starch layer significantly improved the adhesion of the paper cover sheet to the gypsum core layer made from an aqueous gypsum slurry containing 2100 ppm Cl 2 ⁻ anions.

FIG. 16 shows the above results for a 12″×12″×½″ gypsum board with a gypsum core made from stucco containing Cl ⁻ from 2000 ppm NaCl per million parts of calcium sulfate hemihydrate. Figure 2 shows photographs showing the effect of dilute starch solution on the same uncooked starch used in the example of Example 1 and in addition the effect of perforation. FIG. 16 compares the Control Sample Board 2E with the Experimental Sample Board 2F of the present invention. Control Board 2E had a non-perforated backing paper coversheet and no starch layer between the backing paper coversheet and the gypsum core. Experimental sample board 2F of the invention had a perforated paper coversheet and a starch layer between the backing paper coversheet and the gypsum core. For this perforated paper sheet, the distance between adjacent perforations was 1/4 inch. The hole diameter was about 0.01-0.02 inches.

Comparing sample boards 2E and 2F in FIG. 16 with 2000 ppm chloride anion, experimental sample board 2F with the starch layer and pore treatment had a smaller area of exposed gypsum. Therefore, experimental sample board 2F had better adhesion than control sample board 2E.

Also, comparing the experimental sample board 2F of FIG. 16 to the experimental sample board 2B of FIG. 15, which has the same starch layer but no holes, showed that the holes further improved adhesion.

FIG. 17 shows dilutions for a 12″×12″×½″ gypsum board with a gypsum core made from stucco containing Cl ⁻ from 30 ppm NaCl per million parts of calcium sulfate hemihydrate. Figure 1 shows a photograph showing the effect of using a starch solution. This stucco represents conventional low chloride salt stucco. The diluted starch solution was the same as the sample board in FIG. FIG. 17 shows a control sample board 2G with a backing paper coversheet without a starch layer between the backing paper coversheet and the gypsum core. FIG. 17 also shows experimental sample board 2H with a starch layer between the backing paper coversheet and the gypsum core.

Comparing Control Sample Board 2G and Experimental Sample Board 2F with 30 ppm chloride anion, the exposed area of Control Board 2G is similar to that of Experimental Board 2F. This indicates that the starch layer did not significantly improve the bond between the paper and the core in those samples where low levels of chloride salt were present.

Example 3
This example demonstrates the effect of the presence of starch in the gypsum layer on the bond between the coversheet and the gypsum layer of gypsum wallboard prepared using a stucco slurry containing a high salt content.

Sixteen gypsum wallboard samples having dimensions of 12 inches by 12 inches were prepared according to the formulations described in Tables 3-6. The thickness of the sample board was 1/2 inch. A control board (no high salt content in the stucco slurry) was used as a comparison. Boards prepared from high salt (chloride) stucco were tested both with and without starch in the gypsum layer. The source of chloride anions (Cl ⁻ ) is one of sodium chloride (NaCl), magnesium chloride (MgC1 ₂ ), and calcium chloride (CaC1 ₂ ), as shown in the table.

In the table, "HRA" is a heat resistance accelerator. "Pregelatinized starch" refers to pregelatinized corn starch with a cold water viscosity of 90 centipoise. "uncooked starch" refers to uncooked, acid-modified corn starch having a hot water viscosity of 180 BU. "Migratory starch" refers to LC211, a small chain starch commercially available from ADM. All amounts are in grams unless otherwise noted.

A 12 inch by 12 inch by 1/2 inch envelope was made by using Manila paper (46 lb/msf) as the cover and Newsline paper (40 lb/msf) as the backing paper. A slurry was prepared by dipping the dry powder into the solution for 10 seconds, mixing in a Hobart mixer for 10 seconds, followed by foam injection for 5.5 seconds and mixing for an additional 2 seconds. The slurry was poured into a 12 inch by 12 inch by 1/2 inch envelope. After the slurry condensed and hardened, the envelope was sealed by using paper tape. The sealed board was dried at 450°F for 15 minutes and then transferred to a 350°F oven. After drying at 350°F for 20 minutes, the boards were further dried at 110°F for 16 hours.

A dried 12 inch by 12 inch by 1/2 inch board was cut into four 6 inch by 5 inch by 1/2 inch pieces (5 inches in the direction of the production line). A 2.5 inch and parallel 1/8 inch deep straight streak was made on the surface of the board sample from one of the 6 inch edges. The boards were then conditioned at 75°F with 50% relative humidity (RH) for 24 hours before being placed indoors at 90°F with 90% relative humidity (RH). Humidity bonding was tested after 3 hours and 16 hours, respectively, according to the Humidity Board Test below.

The moistened board was snapped along the streak without tearing or stressing the paper on the back side of the board and then the larger (2.5" x 6") portion of the board sample was It was rotated and pushed face up downward, thereby pushing the backing paper on the back side of the board and trying to separate it from the larger portion. The force was increased until the two parts of the board were completely separated. The backside of the larger portion was then examined to determine the percentage of the backing paper surface that was completely detached from the core (referred to as the "fracture rate").

Wet bonding was measured for Samples 4A, 4B, and 4C. After drying the cast board at 450° F. for 15 minutes, the board was cut into four 6 inch by 5 inch by 1/2 inch pieces. Two of the 6" x 5" x 1/2" strips were measured for wet bond immediately and the other two were further dried at 350°F for 20 minutes and 110°F for 16 hours.

Table 7 shows the 3 hour wet bond from Samples 3A and 3B. FIG. 18 is an image showing binding after testing. As seen in FIG. 18, Samples 3A and 3B show good bonding between the paper and the gypsum layer, with no paper delamination observed, while Sample 3B shows control Sample 3A (13 .1 lbs) had a higher wet binding (18.6 lbs).

Tables 8A and 8B list the wet bonding and 16 hour wet bonding results for Samples 4A, 4B, and 4C. FIG. 19 includes images showing the board after wet bonding and 16 hour wet bonding testing. Sample 4B showed poor wet bonding and 16 hours wet bonding due to high salt concentration (2000 ppm Cl). Sample 4C showed higher wet bonding and 16 hour wet bonding compared to Sample 4B, indicating that the addition of uncooked starch improved the bond between the paper and the gypsum layer. As seen in Figure 19, no paper delamination is observed in Samples 4A and 4C, but 50% paper failure is found in Sample 4B.

Table 9 shows the effect of different starches (uncooked vs. migratory starch) on 3 hour wet binding from Samples 5A, 5B, 5C, 5D, and 5E. FIG. 20 includes an image showing the board after 3 hours of humidified bonding testing. Sample 5B demonstrated poor 3 hour wet bonding due to high salt concentration (600 ppm Cl). Samples 5C, 5D, and 5E show good bonding between the paper and the gypsum layer, indicating that the addition of either uncooked or migratory starch can improve bonding between the paper and the gypsum layer. showing. As seen in FIG. 20, no paper delamination is observed from samples 5A, 5C, 5D and 5E, but insufficient paper delamination is observed for sample 5B.

Table 10 shows the effect of different salts on wet binding for 3 hours in samples 6A, 6B, 6C, 6D, 6E, and 6F. FIG. 21 includes images showing bonding after testing for 3 hours of humidified bonding. Samples 6A, 6C, and 6E showed poor 3 hour wet bonding due to the presence of different salts, NaCl, _CaC12 , and _MgC12 . Samples 6B, 6D, and 6F showed good bonding, indicating that the addition of either uncooked or migratory starch greatly improved bonding between the paper and the gypsum layer. As seen in Figure 21, no obvious paper delamination is observed with the addition of starch to samples 6B, 6D and 6F. However, Samples 6A, 6C, and 6D show poor paper release.

In various embodiments, the starch can be native starch, pregelatinized starch, or a combination of native and pregelatinized starch. In some embodiments, it is preferred to add starch to the top skim coat layer and/or the bottom skim coat layer. However, starch can also be added to the core.

Example 4
This example demonstrates the effectiveness of using superabsorbent paper as a coversheet for wallboard containing a set gypsum layer prepared from stucco with a high content of salt impurities. Superabsorbent paper enhances the bond between the paper and the set gypsum core when the set gypsum layer is formed from slurries containing high concentrations of salts.

Specifically, three 1/2″ thick boards (7A-7C) were prepared on a wallboard manufacturing production line. Board 7A was a control board such that the set gypsum core was prepared without any high salt impurities Boards 7B and 7C were each set gypsum cores. was prepared introducing 600 ppm chloride ion by adding a mixture of sodium chloride and magnesium chloride to the formulations listed in Table 11. The amounts of ingredients in Table 11 are given in lb/MSF. ing.

In Table 11, HRA refers to heat resistance accelerator. Pregelatinized starch is a pregelatinized corn starch with a cold water viscosity of 90 centipoise. Uncooked starch is uncooked, acid-modified corn starch with a hot water viscosity of 180 BU. The dispersant is naphthalenesulfonic acid. The retardant is pentasodium diethylenetriamine pentaacetate. STMP refers to sodium trimetaphosphate. Foams were prepared using the HYONIC line of soap products (eg, 25AS) from GEO Specialty Chemicals (Ambler, Pa.) and Polystep B25 from Stepan Company (Northfield, Illinois).

The front coversheet (Manila) of each of Boards 7A-7C was paper having a basis weight of 50 lb and was of conventional (conventional) composition without high absorbency properties. The back coversheet (Newsline) for Comparative Board 7A and Board 7B was paper with a 47 lb basis weight of conventional composition and the back coversheet for Board 7C was a super absorbent paper with a 47 lb basis weight. . Comparative Board 7A has a weight of 1307 lb/MSF and Boards 7B and 7C have a weight of 1305 lb/MSF.

Tests were conducted to determine the effect on bonding between each cover sheet and the set gypsum layer of each board. After the boards exited the production line kiln, they were cut into 5.5 inch by 5.875 inch samples. A 1.0 inch parallel 1/8 inch deep straight stripe was made on the surface of each board from one of the 5.875 inch edges and each board was placed at 75°F/50% relative Conditioned overnight in a humidity (“RH”) room. The conditioned samples were then placed in a 90°F/90% RH chamber. Both the front and back sides of the boards were subjected to humid bonding tests in a 90°F/90% RH room after 3 hours, 16 hours, and 1 week, respectively. The humidified boards were tested according to the following Humidified Board Test.

The humidified board was snapped along the streak without tearing or stressing the paper on the back side of the board and then the larger (4.5" x 5.875") of the board sample was The section was rotated and pushed face up downwards, thereby pushing the backing paper on the back side of the board and trying to peel it away from the larger section. The force was increased until the two parts of the board were completely separated. A higher wet bond load indicates a better bond between the paper and the core. The backside of the larger portion was then examined to determine the percentage of the backing paper surface that was completely detached from the core (referred to as the "fracture rate").

As shown in Table 12, the front sides of the boards in all three conditions exhibited similar wet bond loads and a 0% bond failure rate between the paper and the core. FIG. 22 shows photographs of all three conditions after binding testing. As seen in Figure 22, good bonding between the paper and the core was observed in each condition.

However, as shown in Table 13, wet bonding from the back side of the board had different results. FIG. 23 shows photographs of all three conditions after binding testing. As seen in Figure 23, conditioned board 7B showed poor bonding between the paper and the core, while conditioned boards 7A and 7C showed good bonding between the paper and the core. rice field. Control board 7A, with no added salt, had a high wet bond load and 0% failure rate between the regular backing paper and the gypsum core. However, when 600 ppm chloride was added to the gypsum slurry, Board 7B exhibited a much lower wet bond load and greater than 60% failure rate between the regular Newsline backing paper and the gypsum core.

Unlike Board 7B, when superabsorbent paper was used as the backing paper, Board 7C, formed from the same stucco slurry formulation as Board 7B, had a much higher wet bond load and 0% wet bond load for the bond between the paper and the core. showed the breakage rate of This indicates that superabsorbent paper enhances the bond between the paper and the core, especially when the wallboard contains high concentrations of salt.

Example 5
This example demonstrates the effect of high salt concentration on moisture sensor readings.

A sample resembling a 1/2 inch wallboard was prepared in a laboratory environment. The samples contained gypsum slurry between the cover, backing paper, and sheets. To evaluate the effect of high salt concentration, slurries were made using different amounts of chloride. Specifically, four conditions were represented: 0 PPM chloride, 300 PPM chloride, 600 PPM chloride, and 900 PPM chloride.

All of the samples were dried in a 110° F. oven to constant weight and then weighed using a precision scale to determine bone dry weight. In addition, both radio frequency-based and microwave-based handheld sensors were used to measure the moisture content of each sample. All samples were then conditioned in a 75° F./50% relative humidity chamber for 24 hours and measured using the same radio frequency and microwave based sensor to determine moisture content after conditioning. All samples were conditioned in a 90°F and 90% relative humidity chamber for 24 hours and measured using the same radio frequency and microwave based sensors to determine moisture content after 90/90 conditioning. bottom.

Figures 24A and 24B show that the level of error increases as the PPM salt level increases using a high frequency dielectric based sensor. At the extreme 900 ppm level, dielectric readings range from approximately 8-11% moisture when the actual moisture is only approximately 3%. Microwave-based sensors are insensitive and closely resemble real moisture readings. A moisture difference of as little as 1% can result in an overly dry board, thereby reducing interfacial bonding between the paper and the gypsum core.

All references, including publications, patent applications, and patents, listed herein are individually and specifically indicated that each reference is incorporated by reference and are set forth herein in their entirety. incorporated herein by reference to the same extent.

In the context of describing the present invention (especially in the context of the claims that follow), the terms "a" and "an" and "the" and "at least one" and similar denoting terms Use shall be construed to encompass both singular and plural unless otherwise indicated herein or otherwise clearly contradicted by context. The use of the term "at least one" followed by a list of one or more items (e.g., "at least one of A and B") is used unless stated otherwise herein or the context is clear. construed to mean one item selected from the listed items (A or B), or any combination of two or more of the listed items (A and B), unless contradicted by is. The terms “comprising,” “having,” “including,” and “containing” mean open-ended terms (i.e., “including but not limited to”), unless otherwise specified. ). Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each individual value falling within the range, and unless otherwise indicated herein, each individual Values are incorporated herein as if individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples or exemplary language (e.g., "such as") provided herein is merely intended to make the invention easier to understand, unless otherwise stated in the claims. No limitation is imposed on the scope of the invention. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. We expect those skilled in the art to employ such variations as appropriate, and the inventors believe that the invention may be practiced otherwise than as specifically described herein. intended to be implemented in Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims (20)

A gypsum board comprising a set gypsum core disposed between a front cover sheet and a back cover sheet, said set gypsum core being formed from a slurry comprising water, stucco and a high salt impurity content, said board but below:
(a) holes in the back cover sheet;
(b) said back cover sheet containing super absorbent paper;
(c) starch contained between the set gypsum core and at least one of the cover sheets;
(d)(i) a back skim coat layer defining first and second skim coat surfaces, said back skim coat layer being formed from a second slurry comprising water, stucco, and skim coat starch; a back skim coat layer, wherein said first side of said skim coat faces said back cover sheet and said second side of said back ski coat faces said first core side; and (ii) a second a front skim coat layer defining first and second surfaces, said front skim coat layer being formed from a third slurry comprising water, stucco, and optionally said skim coat starch; facing the second surface of the board core, and the second surface of the front skim coat layer facing the front cover sheet, and wherein said skim-coated starch enhances bonding between said core and at least said back cover sheet, and said second and third slurries may be the same or different. . said salt impurities comprise sodium chloride, potassium chloride, magnesium chloride, calcium chloride, or any combination thereof, said salt impurities comprising at least about 150 ppm chloride anion per 1,000,000 parts by weight of said stucco; 2. The board of claim 1, comprising: At least one of the first slurry, the second slurry, and/or the third slurry contains boric acid in an amount of about 0.01% to about 0.5% by weight of the stucco. A board according to claim 1. 2. The method of claim 1, wherein at least one of the first slurry, second slurry, and/or third slurry contains clay in an amount of about 1% to about 10% by weight of the stucco. board. 2. The gypsum board of claim 1, wherein said back cover sheet is in the form of perforated and/or superabsorbent paper and said board contains starch between said set gypsum core and said back cover sheet. wherein said back cover sheet is in the form of a perforated and/or superabsorbent paper and said board is (i) a back skim-coated layer defining first and second skim-coated surfaces, said back skim-coated layer comprising: formed from a second slurry comprising water, stucco, and skim-coat starch, wherein said first side of said back skim coat faces a backing paper and said second side of said back skim coat faces said second side of said back skim coat; (ii) a back skim coat layer, facing one core face, and (ii) a top skim coat layer defining first and second faces, said top skim coat layer comprising water, stucco, and optionally a third slurry comprising said skim-coated starch, said first side of said front skim-coat layer facing a second side of said board core, and said second side of said front skim-coat layer facing a second side of said board core; a front skim-coated layer, the side of which faces the front cover sheet, wherein the skim-coated starch enhances the bond between the core and at least the back cover sheet; Gypsum board according to claim 1, wherein the slurries may be the same or different. 2. The board of claim 1, wherein said starch is contained between said set gypsum core and said back cover sheet. A method of making a gypsum board, comprising:
(a) mixing at least water, stucco, and foam to form a first slurry;
(b) disposing the first slurry between a front coversheet and a back coversheet to form a board precursor;
(c) cutting the board precursor into boards;
(d) drying the board in the kiln containing at least one high frequency in-kiln moisture sensor, the in-kiln moisture sensor in communication with a controller outside the kiln to obtain an in-kiln moisture reading; generating a value;
(e) using an upstream high frequency moisture sensor and an upstream sensor that is less susceptible to high salt concentrations in the slurry than the high frequency moisture sensor, said upstream sensor being in communication with said controller; measuring moisture content in the board upstream of the kiln to generate a first upstream moisture reading and a second upstream moisture reading, respectively;
(f) correlating the upstream high frequency moisture sensor and the moisture reading from the upstream sensor that is less susceptible to high salt concentrations in the slurry compared to the high frequency moisture sensor;
(g) biasing the high frequency oven moisture sensor to correct for any error in the oven moisture reading when a delta exists between the first and second moisture readings; A method, including said kiln having burner power and/or air extraction associated therewith, said method comprising:
(h) a downstream high frequency moisture sensor and a downstream sensor that is less susceptible to high salt concentrations in the slurry than the high frequency moisture sensor, the downstream high frequency sensor in communication with the controller and measuring the moisture content in the board downstream of the kiln using a rugged sensor to generate a first downstream moisture reading used to bias a second downstream moisture reading; and,
(i) correlating the downstream high frequency moisture sensor and the moisture reading from the downstream sensor that is less susceptible to high salt concentrations in the slurry compared to the high frequency moisture sensor;
9. The method of claim 8, further comprising (j) adjusting the burner power and/or air system to adjust the temperature within the kiln to reduce heating therein. 9. The method of claim 8, further comprising set point control of said burner power, temperature and/or airflow within said kiln. 10. The method of claim 9, wherein at least one of said sensors that are less susceptible to high salt concentrations in said slurry than said high frequency moisture sensor is a microwave sensor. 10. The method of claim 9, wherein the kiln has one zone. 10. The method of claim 9, wherein the kiln has at least two zones. 10. The method of claim 9, wherein the kiln contains at least two in-kiln moisture sensors. said salt impurities comprise sodium chloride, potassium chloride, magnesium chloride, calcium chloride, or any combination thereof, said salt impurities comprising at least about 150 ppm chloride anion per 1,000,000 parts by weight of said stucco; 10. The method of claim 9, comprising: A system for drying boards, comprising:
(a) a kiln containing therein at least one heat source and at least one in-kiln high frequency moisture sensor;
(b) a controller outside the kiln; and (c) an upstream high frequency moisture sensor and an upstream sensor less susceptible to high salt concentrations in the slurry compared to the high frequency moisture sensor in communication with the controller. said upstream high frequency sensor and an insensitive sensor for generating a first upstream moisture reading and a second upstream moisture reading, respectively. 17. The system of claim 16, further comprising burner power and/or air extraction devices associated with said kiln, said burner power and/or air extraction devices in communication with said controller. (d) a downstream high frequency moisture sensor and a downstream sensor that is less susceptible to high salt concentrations in the slurry than the high frequency moisture sensor, the downstream high frequency sensor in communication with the controller and a rugged sensor for generating a first downstream moisture reading and used to bias a second downstream moisture reading;
18. The system of claim 17, wherein the burner power and/or air device can be used to selectively adjust the temperature within the kiln to reduce heating therein. 17. The system of claim 16, wherein at least one of said sensors that are less susceptible to high salt concentrations in said slurry than said high frequency moisture sensor is a microwave sensor. 17. The system of claim 16, wherein the kiln contains at least two in-kiln moisture sensors.

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