JP7377241B2 - Patterned diatomaceous earth plate and its manufacturing method - Google Patents

Description

The present invention relates to a patterned diatomaceous earth plate and a method for manufacturing the same. In the present invention, a pattern means a picture, a pattern, a figure, a character, a symbol, a color, or a combination thereof.

A plate containing diatomaceous earth is used as a foot-wiping mat. Patent Document 1 discloses a foot wiping mat using diatomaceous earth as one of the raw materials and a method for manufacturing the same.

Japanese Patent Application Publication No. 2010-184108

In recent years, when purchasing a product, an increasing number of consumers are paying attention to the product's design as well as its performance. Conventional diatomaceous earth plates were often white or gray, which is the color of diatomaceous earth. In order to enhance the design of the plates, various techniques have been used, such as adding patterns to the surface using unevenness and grooves, and painting the entire plate in a light color. These efforts have been made on the premise that the water absorption performance of the diatomaceous earth plate is not reduced as much as possible.

In order to further enhance the design of the diatomaceous earth plate, the present inventor prototyped a diatomaceous earth plate with a picture or pattern drawn or colored on the surface. As a result, we found that it is not necessarily easy to improve the design of diatomaceous earth plates while maintaining their water absorption performance.

The present invention provides a patterned diatomaceous earth plate that is excellent in design and whose water absorption performance is improved or sufficiently maintained compared to before the pattern is applied, and a method for manufacturing the same.

The method for manufacturing a patterned diatomaceous earth plate according to the first aspect of the present invention includes the following steps in this order.
(A1) A step of forming a first pattern corresponding to the pattern on the surface of the diatomaceous earth plate to be patterned using a first paste material.
(B1) A step of immersing at least the surface of the diatomaceous earth plate in a dye liquid containing a dye.
(C1) A step of washing away the first paste material adhering to the surface.
(D1) Drying the diatomaceous earth plate.

The present inventor tried various dyes and pigments as materials for coloring diatomaceous earth plates. As a result, when a pigment was used, the coloring was insufficient, and when a coating material containing a pigment and a resin was used, the water absorption performance of the colored area of the diatomaceous earth plate was significantly reduced. On the other hand, it has been found that by using a dye, sufficient coloring can be achieved and the water absorption performance of the colored area can be sufficiently maintained. It has also been found that by going through the (D1) step (drying step of the diatomaceous earth plate), the water content of the diatomaceous earth plate decreases, and the water absorption performance may be improved compared to the diatomaceous earth plate before the (A1) step.

The first paste material (for example, mochi paste dissolved in water) used in the step (A1) serves as a mask. The area where the first pattern is formed by the first paste material is not colored because the first dye used in step (B1) does not penetrate into the diatomaceous earth plate. On the other hand, other areas are colored by infiltration of the first dye.

Preferably, the step (B1) includes the following steps in this order.
(b1) Shaking the diatomaceous earth plate horizontally for 5 to 20 seconds while immersed in the dye solution contained in the container.
(b2) Immerse the diatomaceous earth plate in the dye solution for 1 to 5 minutes in a container.
By carrying out step (B1) as described above, color unevenness can be suppressed and the dye can be impregnated to a sufficient depth of the diatomaceous earth plate. From the viewpoint of suppressing discoloration due to use, it is preferable that the dye penetrates to a depth of 200 to 800 μm from the surface of the diatomaceous earth plate after the step (D1).

Preferably, the step (D1) includes the following steps in this order.
(d1) Drying the diatomaceous earth plate after the step (C1) above in the atmosphere for 12 hours or more.
(d2) Drying the diatomaceous earth plate in a drying oven.
By carrying out the step (D1) as described above, cracking of the diatomaceous earth plate can be suppressed, and the original water absorption performance of the diatomaceous earth plate can be expressed.

The first paste material used in step (A1) may contain a first dye of a different color from the dye solution. Thereby, the diatomaceous earth plate can be impregnated with two colors of dyes: the dye contained in the first paste material (first dye) and the dye contained in the dye solution. To impregnate the diatomaceous earth plate with three colors of dyes, before carrying out step (B1), a second paste material corresponding to the pattern is infiltrated with a second paste material containing a second dye of a different color from the first dye. What is necessary is just to carry out the process of forming a pattern. The diatomaceous earth plate may be impregnated with dyes of four or more colors by repeating this process using dyes of different colors.

The method for manufacturing a patterned diatomaceous earth plate according to the second aspect of the present invention includes the following steps in this order.
(A2) A step of forming a first pattern corresponding to the pattern on the surface of the diatomaceous earth plate to be patterned using a first paste material containing a first dye.
(B2) A step of impregnating the diatomaceous earth plate with the first dye.
(C2) A step of washing away the first paste material adhering to the surface.
(D2) Drying the diatomaceous earth plate.

The manufacturing method according to the second aspect differs from the manufacturing method according to the first aspect described above in that the step of immersing the diatomaceous earth plate in the dye solution is not essential. The manufacturing method according to the second aspect may further include the following steps before performing step (C2) in order to impregnate the diatomaceous earth plate with two-color dyes.
(X) Forming a second pattern corresponding to the above pattern using a second paste material containing a second dye of a different color from the first dye.
(Y) A step of impregnating the diatomaceous earth plate with the second dye.

By repeating the above series of steps (X) and (Y) two or more times using paste materials containing dyes of different colors, the diatomaceous earth plate may be impregnated with dyes of three or more colors in total. .

The present invention provides a patterned diatomaceous earth plate. The patterned diatomaceous earth plate has a surface that is patterned with dye-impregnated areas and non-dye-impregnated areas. By preparing diatomaceous earth plates with various patterns drawn on them, consumers' desire to purchase can be increased.

Since the patterned diatomaceous earth plate has a pattern formed by coloring with a dye, its water absorption performance is improved or sufficiently maintained compared to before the pattern is applied. The water absorption performance of the diatomaceous earth plate can be evaluated by the time required for absorbing a predetermined amount (15 cc) of water. Preferably, the time required for the patterned diatomaceous earth plate to absorb 15 cc of water from its surface is less than 60 seconds.

From the viewpoint of suppressing discoloration due to use, it is preferable that the colored region of the patterned diatomaceous earth plate is soaked with dye to a depth of 200 to 800 μm from the surface. The above-mentioned pattern may be drawn with one color of dye, or may be drawn with two or more colors of dye.

According to the present invention, there are provided a diatomaceous earth plate with a pattern that is excellent in design and whose water absorption performance is improved or sufficiently maintained compared to before the pattern is applied, and a method for manufacturing the same.

FIG. 1 is a photograph showing an embodiment of a patterned diatomaceous earth plate according to the present invention. FIG. 2 is a schematic cross-sectional view showing an enlarged structure near the surface of the patterned diatomaceous earth plate shown in FIG. 3(a) to 3(c) are schematic cross-sectional views showing the manufacturing process of the patterned diatomaceous earth plate shown in FIG. 1. FIGS. 4(a) to 4(c) are schematic cross-sectional views showing other embodiments of the method for manufacturing a patterned diatomaceous earth plate according to the present invention. FIGS. 5(a) to 5(d) are photographs showing variations in patterns. FIGS. 6(a) to 6(d) are photographs showing variations in patterns. FIGS. 7(a) to 7(d) are photographs showing variations in patterns.

Embodiments of the present invention will be described below with reference to the drawings as necessary. Note that the present invention is not limited to the following embodiments.

<Patterned diatomaceous earth plate>
FIG. 1 is a photograph showing the top surface of a patterned diatomaceous earth plate according to this embodiment. FIG. 2 is a schematic cross-sectional view showing an enlarged structure near the surface of the patterned diatomaceous earth plate 10 shown in FIG. The patterned diatomaceous earth plate 10 (hereinafter simply referred to as "plate 10" in some cases) is used as a foot wiping mat (bath mat). In this case, the shape of the plate 10 in plan view is, for example, a rectangle with a side length of 250 to 1000 mm. The size of the plate 10 may be appropriately set depending on whether it is for home use or for large-scale facilities. The thickness of the plate 10 may be approximately 6 to 15 mm from the viewpoint of strength.

The plate 10 has a pattern of a combination of a picture 1 composed of flowers, leaves, and stems and a geometric ground pattern 2 drawn on the surface 10F. This pattern is drawn by a region _R1 soaked with dye and a region _R2 not soaked with dye (see FIG. 2). This pattern is monochromatic and colored with one type of dye. Diatomaceous earth plates are made from diatomaceous earth, which is a natural material, and may have uneven coloring due to minerals or limescale on the surface. By adding a pattern (particularly a geometric background pattern) to the surface of the diatomaceous earth plate, the color unevenness of the diatomaceous earth plate can be made less noticeable.

In the region _R1 of the plate 10, the depth to which the dye has penetrated (depth D in FIG. 2) is preferably 200 to 800 μm, more preferably 300 to 800 μm. When this depth is 200 μm or more, discoloration due to use can be suppressed, and the plate 10 tends to remain colored for a sufficiently long period of time. On the other hand, when this depth is 800 μm or less, the time required for coloring with the dye tends to be shortened. According to the studies conducted by the present inventors, when the plate 10 is impregnated with a dye, the dye is impregnated to a sufficiently uniform depth in the colored area, whereas when the plate 10 is impregnated with a pigment, the dye is impregnated with a sufficiently uniform depth in the colored area. There were variations in the depth at which the pigment penetrated.

Since the plate 10 has a pattern formed by coloring with a dye, its water absorption performance is improved or sufficiently maintained compared to before the pattern is applied. The time required for 15 cc of water to be absorbed from surface 10F of plate 10 is preferably less than 60 seconds, more preferably less than 50 seconds, and even more preferably less than 40 seconds. This time is determined by the following water absorption test.

(Water absorption test)
Drop 15 cc (1 tablespoon) of water from a position approximately 30 mm above the plate surface. The time from when the water droplet reaches the plate surface until the plate absorbs the water droplet and the water reflection disappears is measured.

<Method for manufacturing patterned diatomaceous earth plate>
Next, a method for manufacturing the plate 10 will be described with reference to FIGS. 3(a) to 3(c). The method for manufacturing plate 10 includes the following steps in this order.
(A1) A step of forming a pattern corresponding to the pattern shown in FIG. 1 on the surface 5F of the diatomaceous earth plate 5 to be patterned using the paste material 6 (see FIG. 3(a)).
(B1) Step of immersing the diatomaceous earth plate 5 in the dye solution L containing the dye (see FIG. 3(b)).
(C1) A step of washing away the paste material 6 remaining on the surface of the diatomaceous earth plate 5 with water (see FIG. 3(c)).
(D1) Drying the diatomaceous earth plate 5 after washing with water.

FIG. 3A is a schematic cross-sectional view showing a state in which the opening 8a of the screen 8 disposed on the surface 5F of the diatomaceous earth plate 5 is filled with the paste material 6. FIG. 3(b) is a schematic cross-sectional view showing the state in which the diatomaceous earth plate 5 is immersed in the dye solution L. FIG. 3(c) is a schematic cross-sectional view showing the state after the paste material 6 remaining on the surface of the diatomaceous earth plate 5 has been washed away with water. The plate 10 is manufactured through the drying process in step (D1). Each step of (A1) to (D1) will be explained below.

Step (A1) is a step of forming a pattern corresponding to the pattern shown in FIG. 1 on the surface 5F of the diatomaceous earth plate 5 using the paste material 6. The diatomaceous earth plate 5 preferably has sufficient water absorbency, and when the dry mass of the diatomaceous earth tile is 100 parts by mass, it is preferable that it can absorb 80 parts by mass or more (more preferably 90 parts by mass or more) of water. The upper limit of the amount of water that the diatomaceous earth plate 5 can absorb (based on the mass of the diatomaceous earth plate when dry) is, for example, 107 parts by mass, or may be 100 parts by mass, from the viewpoint of material costs and the like. Such diatomaceous earth plates can be purchased from Ube Industries Kenzai Co., Ltd. As the paste material 6, for example, mochi paste dissolved in water can be used.

The step (A1) includes, for example, the following steps.
(a1) Placing the screen 8 having the openings 8a corresponding to the pattern shown in FIG. 1 on the surface 5F.
(a2) Applying the paste material 6 to the upper surface of the screen 8 and the surface 5F exposed to the opening 8a using a scoogee (wiper).
(a3) Remove the screen 8 from the surface 5F.
(a4) Naturally drying the paste material 6 on the surface 5F.

The screen 8 is made of synthetic fiber such as polyester, and is placed on the surface 5F of the diatomaceous earth plate 5 while being stretched around an aluminum frame. Since the diatomaceous earth plate 5 quickly absorbs water, after removing the screen 8, the paste material 6 becomes sufficiently dry after being air-dried for about 1 minute.

The area on the surface 5F where the paste material 6 is placed is not dyed because the dye does not penetrate therein. That is, this region becomes region _R2 on the plate 10. On the other hand, since the surface 5F is exposed in the area where the paste material 6 is not placed on the surface 5F, the dye penetrates and is dyed. That is, this region becomes region _R1 on the plate 10. By performing step (A1) as described above, the paste material 6 can be efficiently placed on the surface 5F. This contributes to mass production of the plate 10.

Step (B1) is a step of immersing the diatomaceous earth plate 5 after step (A1) in a dye solution. The dye liquid is an aqueous solution in which a dye of a desired color is dissolved in water. One type of dye may be used alone, or two or more types of dyes may be used in combination to adjust the color tone. Examples of the color tones include aqua blue, rose pink, clean tea, gray, brown, honey gold, cherry blossom color, and purple. The dye solution may be prepared by blending, for example, about 0.5 to 10 g of dye to 10 L of fresh water. The concentration of the dye may be adjusted depending on the physical properties of the diatomaceous earth plate 5 and the type of dye. A step of preparing a plurality of types of dye liquids having different concentrations, immersing a test piece of a diatomaceous earth plate in each of these dye liquids, and selecting an appropriate concentration may be carried out in advance.

The step (B1) includes, for example, the following steps.
(b1) Shaking the diatomaceous earth plate 5 horizontally for 5 to 20 seconds while immersing the diatomaceous earth plate 5 in the dye solution contained in the container.
(b2) Immerse the diatomaceous earth plate 5 in the dye solution for 1 to 5 minutes in a container.

By performing step (B1) in this way, color unevenness can be suppressed and the dye can be soaked into the surface 5F to a sufficient depth.

Step (C1) is a step of washing away the paste material 6 remaining on the surface 5F of the diatomaceous earth plate 5 with water. Paste material 6 remaining on surface 5F can be washed away using a brush, for example.

Step (D1) is a step of drying the diatomaceous earth plate 5 after washing with water. The step (D1) includes, for example, the following steps.
(d1) Drying the diatomaceous earth plate 5 after washing with water in the atmosphere for 12 hours or more.
(d2) Drying the diatomaceous earth plate 5 after the drying in a drying oven.

The drying time in the step (d1) may be set depending on the season (temperature and humidity), and the upper limit may be, for example, about one week, or about four or three days. The timing of transition from the step (d1) to the step (d2) may be determined based on the water content of the diatomaceous earth plate 5, for example. The set temperature and drying time of the drying oven in the step (d2) may be determined based on the water content or water absorption performance of the diatomaceous earth plate 5. By performing step (D1) in this way, cracking of the diatomaceous earth plate 5 can be suppressed, and a plate 10 having water absorption performance equivalent to that of the diatomaceous earth plate 5 can be obtained.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in the above embodiment, the patterned diatomaceous earth plate is used as a foot wiping mat, but the patterned diatomaceous earth plate may also be applied to coasters, kitchen draining plates, and shoe dehumidification plates, for example. The shape and size of the patterned diatomaceous earth plate may be appropriately set depending on the intended use.

In the above embodiment, a case where a monochromatic pattern is applied to the diatomaceous earth plate is exemplified, but a multicolored pattern may be applied to the diatomaceous earth plate using two or more kinds of dyes. For example, the paste material 6 used in step (A1) may contain a dye of a different color from the dye liquid L. Thereby, the diatomaceous earth plate 5 can be impregnated with two colors of dyes, that is, the dye contained in the paste material 6 and the dye contained in the dye liquid L. Note that in order to impregnate the diatomaceous earth plate 5 with dyes of three colors, before performing step (B1), a pattern is formed using a second paste material containing a dye of a different color from the dye contained in the paste material 6. What is necessary is just to implement the process of forming the second pattern on the diatomaceous earth plate 5. By repeating this process using dyes of different colors, the diatomaceous earth plate 5 may be impregnated with dyes of four or more colors.

Further, in the above embodiment, the case where the diatomaceous earth plate is colored by immersing the diatomaceous earth plate in a dye solution is illustrated, but the diatomaceous earth plate may be colored only with a paste material containing a dye (for example, colored paste). The dye contained in the paste material may be transferred to the diatomaceous earth plate. The manufacturing method of this embodiment includes the following steps in this order.
(A2) A step of forming a pattern corresponding to the pattern on the surface of the diatomaceous earth plate 5 using the paste material 7 containing dye.
(B2) A step of impregnating the diatomaceous earth plate 5 with the dye contained in the paste material 7. (C2) A step of washing away the paste material 7 adhering to the surface.
(D2) Drying the diatomaceous earth plate 5.

FIG. 4(a) is a schematic cross-sectional view showing a state in which the opening 9a of the screen 9 disposed on the surface 5F of the diatomaceous earth plate 5 is filled with the paste material 7 containing the dye. FIG. 4(b) is a schematic cross-sectional view showing a state in which the dye contained in the paste material 7 is impregnated into the diatomaceous earth plate 5. FIG. 4(c) is a schematic cross-sectional view showing the state after the paste material 7 adhering to the surface of the diatomaceous earth plate 5 has been washed away with water.

The step (A2) includes, for example, the following steps.
(a1) A screen 9 having an opening 9a corresponding to the pattern to be drawn is arranged on the surface 5F.
(a2) Applying the paste material 7 to the upper surface of the screen 9 and the surface 5F exposed to the opening 9a using a scoogee (wiper).
(a3) Remove the screen 9 from the front surface 5F.

In step (B2), the penetration depth of the dye can be adjusted by overcoating the paste material 7. The area on the surface 5F where the paste material 7 is placed is soaked with dye and dyed. That is, this region becomes region _R1 on the plate 20. On the other hand, the area on the surface 5F where the paste material 7 is not placed is not dyed. That is, this region becomes region _R2 on the plate 20. Although the case of dyeing using the screen 9 is illustrated here, the paste material 7 may be applied onto the surface 5F with a brush or a brush without using the screen 9. Note that the (C2) step and the (D2) step may be carried out in the same manner as the (C1) step and (D1) step when a dye liquid is used.

In order to impregnate the diatomaceous earth plate 5 with two colors of dyes, the following steps may be further included before performing step (C2).
(X) A step of forming a second pattern corresponding to the pattern on the diatomaceous earth plate 5 using a second paste material containing a second dye of a different color from the dye contained in the paste material 7.
(Y) A step of impregnating the diatomaceous earth plate 5 with the second dye.

By repeating the series of steps (X) and (Y) two or more times using paste materials containing dyes of different colors, the diatomaceous earth plate 5 may be impregnated with dyes of three or more colors in total.

A multicolored pattern may be drawn on the diatomaceous earth plate 5 by combining the above-mentioned method of applying a pattern using a dye solution and the method of applying a pattern using a paste material containing a dye. It is preferable to use a dye liquid for the first dyeing to draw the background pattern, and for the second and subsequent dyeings to use a paste material containing the dye to draw the picture.

The pattern drawn on the diatomaceous earth plate 5 is not limited to that shown in FIG. 1, and includes various patterns as shown in FIGS. 5 to 7.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

The following materials were prepared.
・Diatomaceous earth plate: Ashikai bath mat compact (size: 340mm x 430mm, manufactured by Ube Industries Kenzai Co., Ltd.)
・Color of dye: Purple ・Dye liquid: Aqueous solution prepared by adding 5g of the above dye to 10 liters of clean water ・Paste material: Resistant glue (mochi paste dissolved in water)
・Screen type: Consists of a polyester screen and an aluminum piece that holds the screen.The screen used was one with openings for applying a geometric pattern to the entire diatomaceous earth plate.

(Example)
After drying the diatomaceous earth plate in an environment of 60° C. for 3 days, it was placed in a constant temperature and humidity machine adjusted to 23° C. and 50% RH, and left standing until the weight stabilized. The water content of the diatomaceous earth plate was 1.4%. With the screen placed on the surface of the diatomaceous earth plate, the paste material was applied using a squeegee. After removing the screen, the paste material on the diatomaceous earth plate was allowed to air dry for about 1 minute. Next, the diatomaceous earth plate immersed in the dye solution was shaken horizontally for 10 seconds, and then immersed in a stationary state for 3 minutes. After washing off the paste material remaining on the diatomaceous earth plate taken out from the dye solution, it was cured for two days in a place out of direct sunlight. Thereafter, it was dried for 5 hours in a drying oven with a set temperature of 100°C. Four patterned diatomaceous earth plates according to the example were produced through each of these steps. When the cross section of the patterned diatomaceous earth plate was observed under magnification, it was found that the dye had penetrated to a sufficiently uniform depth. The depth of penetration of the dye was measured at five arbitrary locations, and the average value was 730 μm.

(Comparative example)
After drying the diatomaceous earth plate in an environment of 60° C. for 3 days, it was placed in a constant temperature and humidity machine adjusted to 23° C. and 50% RH, and left standing until the weight stabilized. Thereby, three diatomaceous earth plates according to the comparative example were prepared. The water content of the diatomaceous earth plate was 1.4%.

(Water absorption evaluation)
The water absorbency of the patterned diatomaceous earth plate according to the example and the diatomaceous earth plate according to the comparative example was evaluated as follows. That is, 15 cc (1 tablespoon) of water was dropped from a position approximately 30 mm above the plate surface. The time from when the water droplet reached the plate surface until the plate absorbed the water droplet and the reflection by water disappeared (water absorption time) was measured. The average water absorption time of the patterned diatomaceous earth plate of Example was 26.8 seconds. On the other hand, the average water absorption time of the diatomaceous earth plate of the comparative example was 26.3 seconds. The water absorption performance of the patterned diatomaceous earth plate of the example was completely comparable to that of the diatomaceous earth plate of the comparative example.

1... Picture, 2... Ground pattern, 5... Diatomaceous earth plate, 5F... Surface of diatomaceous earth plate, 6, 7... Paste material, 8, 9... Screen, 8a, 9a... Opening, 10, 20... Diatomite plate with pattern, 10F...Surface of patterned diatomaceous earth plate, D...Depth, L...Dye solution, _R1 ...Region where dye is soaked, _R2 ...Region where dye is not soaked

Claims (8)

(A2) forming a first pattern corresponding to the pattern on the surface of the diatomaceous earth plate to be patterned using a first paste material containing a first dye;
(B2) impregnating the first dye into the diatomaceous earth plate;
(C2) washing away the first paste material adhering to the surface;
(D2) drying the diatomaceous earth plate;
A method for manufacturing a patterned diatomaceous earth plate, including in this order. (A2) The process is
(a1) disposing a screen having openings corresponding to the pattern to be drawn on the surface of the diatomaceous earth plate;
(a2) applying the first paste material to the top surface of the screen and the surface of the diatomaceous earth plate exposed at the opening with a scoogee;
(a3) removing the screen from the surface of the diatomaceous earth plate;
The method for producing a patterned diatomaceous earth plate according to claim 1, comprising: in this order. The method for manufacturing a diatomaceous earth plate according to claim 1 or 2, wherein the first pattern is a ground pattern. (C2) Before carrying out the process,
(X) forming a second pattern corresponding to the pattern with a second paste material containing a second dye of a different color from the first dye;
(Y) impregnating the second dye into the diatomaceous earth plate;
The method for producing a patterned diatomaceous earth plate according to any one of claims 1 to 3, further comprising: (A1) forming a first pattern corresponding to the pattern on the surface of the diatomaceous earth plate to be patterned using a first paste material;
(B1) immersing at least the surface of the diatomaceous earth plate in a dye solution containing a first dye;
(C1) washing away the first paste material adhering to the surface;
(D1) drying the diatomaceous earth plate;
(A2) forming a second pattern corresponding to the pattern on the surface of the diatomaceous earth plate using a second paste material containing a second dye;
(B2) impregnating the second dye into the diatomaceous earth plate;
(C2) washing away the second paste material adhering to the surface;
(D2) drying the diatomaceous earth plate;
A method for producing a diatomaceous earth plate, including in this order. The method for manufacturing a diatomaceous earth plate according to claim 5, wherein the first pattern is a ground pattern and the second pattern is a picture. A patterned diatomaceous earth plate having a surface patterned with areas impregnated with dye and areas not impregnated with dye,
The pattern is a patterned diatomaceous earth plate including a ground pattern drawn by impregnation with the first dye. 8. The patterned diatomaceous earth plate according to claim 7, wherein the pattern further includes a picture drawn by impregnation with a second dye.

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