US1625947A - For castihg clay blocks and the like and method of molding - Google Patents

Description

1,625,947 Aprll 26 1927' J. M. LAMBIE ET AL MOLD EOR CASTING CLAY BLOCKS AND THE LIKE AND METHOD OF MOLDING Filed Jan. 10. 1925 FIG. 1 7

Sheets-Sheet 1 8 /7 INVENTORS April 26 ,--1927. 1,625,947

J.-M. LAMBIE ET AL MOLD FOR C! STIN G CLAY BLOCKS AND THE LIKE AND METHOD OF MOLDING F'l d J .10. 1925 25-; 26 FIG, 3 l e 4 Sheets Sheet 2 f FIG. 4'

1,625,947 April 26 J. M. LAMBIE ET MOLD FOR CASTING CLAY BLOCKS AND THE LIKE AND METHOD OF MOLDING Filed Jan 10. 1925 4 Sheets-Sheet 3 FIG 6 INVENTOR April 26 J. M. LAMBIE ET AL MOLD FOR CASTING CLAY BLOQKS AND THE LIKE AND METHOD OF MOLDING 4 Sheets-Sheet 4 Filed Jan 10, 1925 9 FIG.1O FIGLH Patented Apr. 26, 1927.

UNITED STATES PATENT OFFICE.

JAMES M. LAMBIE AND DONALD XV. ROSS, OF WASHINGTON, PENNSYLVANIA.

MOLD FOR CASTING CLAY BLOCKS AND THE LIKE AND METHOD OF MOLDING.

Application filed January 10, 1925.

Our invention relates to molds for and a method of casting clay blocks, pots and other shapes, and its primary object is to provide an improved mold structure where by blocks of large size, good quality and accurate shape .iay be conveniently cast- :lrom clay or other ceramic materials.

One of the well known methods of forming articles from clay consists in susperuling the clay in water by the use of deliocculating agents such as alkali-metal hydroxides, the slip thus produced being poured into molds and allowed to solidify, :1 l ter which the articles are dried and fired. t has not heretofore been thought possible to apply this method to the production of large blocks such as tank blocks for glass furnaces. The maximum thickiiess which could be cast by the methods and apparatus heretofore employed has been about five inches.

We have developed a system for casting ceramic articles whereby we are able to cast large blocks two feet or more in thickness. This casting system is described and claimed in our copending application for Letters Patent, Serial No. 757,422, filed December l92-.l-.

Tie present application deals with the structure of the molds which we employ. These molds consist of side and bottom walls constructed separately and arranged to be fastened securely together. The inner or working surface of the walls and bottom are composed of plaster of Paris or other suitable porous material. The mold sections are, however, so constructed as to engage each other in metal-to-metal or wood-t-o-wood contact in order to increase the accuracy and quantity of the blocks as will he explained more fully below. The mold sections are of sullicient strength to enable them to withstand the high pressures to which they are subjected in molding large blocks and the plaster linings of the mold sections may be reinforced with wire netting or the like, if desired.

We find that in drying such large ceramic masses as tank blocks that the greater the percentage of the outer surface of the porous wall that is exposed to the external air the more rapid is the drying of the ware.

If the porous walls be entirely backed up by supporting plates that are substantially non-porous. were made in them will not dry sulficiently to permit removal of the walls Serial No. 1,593.

for a long period, for as water enters the porous medium the air contained in the pores thereof must be permitted to escape, and later moisture must escape.

ln drying such large ceramic masses as tank blocks it has proved excessively expensive, very cumbersome, and otherwise impracticable to use porous walls of sufficient volume so that they act as reservoirs lor any large percentage of the water withdrawn from the blocks.

8 find that by making the porous walls as thin as possible, with due regard for sircng'tli, and having their external surfaces exposed to the air, that drying goes on rapidly and satisfactorily and that only a small percentage of the water actually lcaving the blocks is to be found in the porous wall at any one time. Thus during drying of the block moisture is continually passing from the block thru the porous wall and off from the outer surface of the porous wall. To accomplish this end we mount the porous material in a frame and back it up with just sullicient lattice work to keep it from bulging outward while in service.

In those cases where it is desirable that drying of certain parts of the ware exposed to the porous walls be retarded, the parts of the porous walls adjoining those parts of the ware are made less porous.

If desired, the porosity may be graded from one part of the porous wall to another, by treating portions of the outer or inner surfaces of the porous walls as may be desired, with a suitable number of applications of substances that will penetrate or adhere thereto, and that will result in partially closing the pores in the porous walls. Fluid paraffin is one such substance that we use for this purpose.

Certain wares that we make tend to dry faster at the top than elsewhere. In such cases we use the last above described artifice to retard the drying of the tops of the blocks.

Most tank blocks are surfaced to a certain predetermined size when they are dry and before they are fired. Some tank blocks are even surfaced to exact size after they have been fired. These surfacing operations con siderably increase the cost of the finished block.

. The degree to which we can obtain exactly rectangular blocks having plane sides, and being to size, by use of the metal molds hereinafter described makes it possible -for us to mold blocks so accurately that substantially the only surfacing necessary is that required to remove sutlicient material from the tops of the blocks so that they will be the proper height after firing. This rectangular form is obtained by having the working face of the base member truly rectangular, the end walls in contact with rigid side walls, the side walls in contact with rigid end walls, and having all bearing surfaces accurately machined. As clay wares, such as tank blocks, shrink in drying and firing, we make the size and shape of the molds such as will compensate for such shrinkage. For example, in the ease of tall blocks, we taper the molds so that they will be slightly larger at the top than at the bottom.

Similar molds can be constructed in which the frame members etc. are oi woof.

Many mixes that may be used in the manut'acture oi tank blocks by our process, tend to shrink more in drying in the top two or three inches of block than d es the balance oi the block. lVhere necessary to overcome this difficulty, we construct the molds suitably taller than would be required to produce a block of the exact height (lQSllit-Btl, fill this mold well above the final desired height, and after the block is dry cut it to the desired height, thereby removing the top shrunken portion.

In the accompanying drawings which show a mold constructed in accordance with our invention, Fig. 1 is a plan view of the complete mold with the sections secured together and rady for receiving the charge of clay; Fig. 2 is a longitudinal vertical sectional View, the section being taken substantially on the line 22, Fig. 1; Fig. 3 is a transverse vertical sectional view, the section being taken substantially on the line 3 3, Fig. 1; Fig. 4; is an enlarged hori zontal section through one corner of the assembled mold, the s-ction be ng taken substantially on the line 4%, Fig. 3; Fig. 5 is a plan view of the bottom member oi the mold with the plaster omitted; F 6 is a view, partially in plan and partially in section. of a modified. form of mold; F 7 is an elevational view, partially in section, of the mold of Fig. 6; Fig. 8 is a cross sectional View thereof; Figs. 9, l0 and 11 are end elevation views of side, end and intermediate walls of the mold of Fig. 6; and 12 is a sectional view of one of the bottom mold members.

In the drawings, the numerals 2 indicate a pair of spaced parallel members forming a base upon which is mounted a rectangular frame composed of side members 3,.end members 4, longitudinal bars 5 extending between theend members 1, and one or more tla'IiSVeP-i spacersli. 1

ear-ems Fig. 1'.

lac base members 2 are provided at their outer ends with upstanding cars 7 having screw-threaded openings through which e);- tend clamping screws 8. Between the ears 7 and the side members 3 the base members 2 carry benches 9 for supporting side walls which are indicated generally by the numerals 10. and which have at their lower ends flanges 11 which are clamped by the scre 8 against he edges ol the side mem- 3 of the rectangular frame.

Formed integral with or secured to the base members 2 are arms which project lengthwise beyond and beneatl the end menn hers at. of the bottom frame. The arms 12 carry upstanding cars 13 which, like the cars 7, are provided with scrcw-tln'eaded openings to receive bolt-s The arms 12 carry benches 15 for supporting end walls indicated generally by the numerals it} and these end walls, as shown in Fig. 2, are clamped by means of the bolts 1 against the outer edges of the end members t of the bottom frame.

The base members 2 are provided with horizontal lugs 17 which form feetto support the entire structure upon a floor. a truck, or any other convenient support, and these lugs may be perforated as shown at id to admit bolts or screws -lor fastening the mold structure in place. l

lfiach oi? the side sections 10 ot' the mold is preferably composed of a single castin having the form of a rectangular latticed iranie having upper and lower members 20 and Q l, respectively, and end members 22. The flanges 11 already D'lQYlillOllGtl extend outwardly from the bottom members 21 and are joined by upright ribs two of which are formed in each of the side wall frames as shown in Fig. 2. The upper portions of the upright ribs 22-} taper upwardly as shown in liig. 3, and are intersected by horizontal ribs 24: which conform in width oi the ribs The ribs 23 and 2% thus form a rigid latticed construction which increases progressively in strength from top to bottom.

At the top of each of the side wall frames is formed a pair of U-shapcd socket members which, as shown, are cast integral ith the wall frame and are disposed at the upper ends of the vertical. ribs W'hen the mold is assembled as shown in Figs. 1

of the drawings, buckstay bolts are t0 0 placed in the sockets 25 and compr as side frames rigidly a ainst the end frames. F or the purpose of iorining accurate joints between the side tran'ies and the end frames. the side frames are provided with vertical notches at their edges as shown at 37. l l. and these notches receive correspondingly notched cornersQS of the end frames, th ese corners being formed by notching the side members of the end times as will be appar.

his

At each of the two upper corners of each side wall frame is formed a pair of vertically spaced ears 30, and between the lugs of each pair an eye-bolt 31 is pivotally mounted. These eye-bolts are provided with nuts 32 for clamping the end frames to the side frames, and for this purpose the end frames are provided at. their upper edges with trans-- verse projecting strips 33, the ends of which form sockets to receive the eyc-bolts 31, as best shown in The construction of the frames for the end walls of the mold similar in a gene 'al way to the construction of the side wall frames, with the exception that the end walls, as shown, are narrow enough to be sufficiently rigid without the use of intermediate vertical ribs such as the ribs 23 of the side wall frames. Each of the end wall frames includes top and bottom members 37 and 36, respectively, side members 37, and spaced horizontal ribs 38 conforming in width to the tapering shape of the side members 37. A flange 39 projects outwardly from the lower member 36 of each frame and is provided between its ends with bosses 40 to form bearing surfaces for the clamping screws 14.

It will be observed on Figs. 2 and 3 that the intermediate lengthwise and transverse elements, 5, 6, 23, 24': and 38, of the bottom, side and end frames, are offset from the planes of the interior surfaces of the frames, in order that these intern'iediate elements shall not project to the interior or molding surfaces of the mold when the plaster lin ings have been applied to the frames. The plaster lining of the bottom frame is shown at s1, and the plaster linings of the side and end frames are shown at s2 and 43, respec tively. Reinforcing material such as wire mesh may be imbedded in the plaster linings as shown at slat, but such reinforcement may be omitted. if desired.

It will be particularly noted that the side and end walls engage each other and also engage the bottom member of the mold with metal-to-metal contact, or with woodto-wood contact in the case of wooden frames. That is to say, the joints between all of the side. end and bottom members consist of metal or wood surfaces, and such surfaces should be carefully machined to accurate form. This insures that the mold will always be assembled with the parts in perfectly accurate relation, which would not be practical if the joints were made between surfaces of plaster or between one metal or wood surface and one plaster surface.

Although it is important that the joints between the mold elements be thus constructed with metal-to-metal or wood-towoodcontact, it is equally important that the interior or working surfaces of the mold shall consist of plaster as completely as possible in order that all parts of the molded article may dry evenly. For this reason we modify the frame members adjacent to the corners so as to expose as large an area as possible of the plaster linings. Such modifications of the frame members is best shown in Fig. -il-, and is also shown at the lower corners of the mold in Figs. 2 and 3. l'le'fcrriug to Fig. 4, the upright side member of the side frame is cut away as shown at 45 so as to bring the plaster lining 12 nearly to the joint between the side frame member 22 and upright end frame member 37. In a somewhat similar manner the upright side men'iber 37 of the end frame is beveled off as shown at lli, Fig. 4-. The plaster lining 42 of the side wall-is thus brought nearly to the plaster lining 43 of the end wall.

e apply the plaster linings to the several mold sections by providing a horizontal flat surface, suitably consisting of a sheet of plate ghss. placing upon this fiatsurface the wall frame to be supplied with plaster, and pouring into the frame and upon the plate glass sufficient liquid plaster of Paris slip to partially fill the frame and embed the ends of the transverse intermediate members of the frame. The side and end members of the frame rest upon the glass and prevent the plaster from running out. hen the plaster has set. the surface of the plaster which rested against the. plate glass is perfectly flat and is flush with the surface of the frame. If wire mesh or other reinforcing material is employed, such material is placed between the plate glass and the metal frame before the plaster is poured. This method of forming the mold sections enables us to cast large clay blocks so accurately that no grinding of the block is required after molding except on the upper surfaces of the blocks. This produces a great saving in labor as well as a minimum reworking of cuttings from the bloclr.

In assembling the mold described above, the side walls are placed upon the benches 9 of the base members 2. and the end walls are placed upon the benches 15 of the supports 12. The buclrstay bolts 26 are then placed across the mold in the sockets 25 and the eye-bolts 31 are swung into position between the ribs 33 of the end frames, The set crews 8 and 1d and bolts 26 and 31 are then tightened, and the mold is ready for use.

The complete mold may conveniently be transported on an elevating truck to bring the mold beneath the casting spout and thereafter to remove the mold to a convenient place where it is left until "the cast block is dried out sufliciently to render the block selfsustaining, and the side walls of the mold are then removed. By loosening the clamping bolts and nuts, the side walls maybe easily taken away and the cast block may be left resting upon the bottom of the mold until it has cured sufficiently for firing.

By the construction described above we provide a mold which has great strength and res'stance against outward expansive strains While, at the same time, substantially the whole interior of the mold is composed of material through which moisture may readily escape. This combination of great mechanical strength with the provision for allowing moisture to escape over practically the whole area of the mold, we believe to be novel with the present invention.

An addition and very import-ant feature of this mold is its high degree of accuracy. The mold remains around the block until the block is hardened. Because of the very small amount of water, in the casting material. which we employ, brought about by the use of certain reagents as claimed in our copending application for Letters Patent, Serial. No. 7%,059 filed October 16, 1924:. and the small amount of plastic clay used, according; to the process described and claimed in our copending application, Serial No. 19,737, filed March 31, 1925, the drying shrinkage of the cast articles is very small and hence the chance of distortion in drymg is at a minimum. The casting system set forth. in the copending application, Serial No. 757,422 includes the operation of covering the top of the freshly cast block with paraflii'i wax or the like, which. when properly placed on. the top of the block, forms acontiuous layer that adheres to the sides of the mold. The paraflin not only prevents the water from evaporating from the surface of the clay but prevents evaporation through the joint. between the clay and the mold, at the top. We find that, with this treatment, the block dries, with sides that are substantially straight, within the allowable variation for tank blocks, without further surfacing. If, however, the paraffin is not continuous and does not adhere to the sides of the mold, evaporation takes place through a fine crack at the top between the freshly cast block and the mold, which results in the block being slightly smaller at the top than at the middle, If the sides of the mold are parallel and the paraffin coating is properly applied in the manner just described, the block will dry with straight sides, but will be slightlysnialler at the top than at the bottom. This is caused by the bottom portion of the block drying under the pressure of the clay above it, and consequently shrinking less than theupper portions of the block. If a. perfectly true and square block is desired, the mold may be made slightly smaller at the bottom than at the top; with its sides tapering to conform, thus compensating for the effect of pressure onthelower portioiiis of the block during.- dryin Although we prefer to use paraffin on the top of our blocks to keep one side of the block in a fluid condition until the center of the block has substantially set, we find it readily possible to make a block in a mold having four porous sides and one side substantially impervious to the passage of moisture. For example, we can construct a mold. with four vertical porous sides and resting on a bottom covered with a sheet of rubber, the top of the block being left uncovered. After casting, the top rapidly sets, moisture is also lost through the porous sides, and lastly, the center of the block dried and the bottom portion being prevented from hardening because of its immediate contact with. the rubber sheet, is drawn upward by the contraction of the mid-portion of the block, to allow shinkage of the interior or mid-portion of the block without cracking. The accurate shape of the cast blocks is also promoted by the nature of the casting composition which we preferably employ. l ve refer particularly to the use of cyanite in these casting mixtures, which enables the burning shrinkage to he reduced to Zero. lVith zero burning shrinkage, the chance of distortion in burning is at a minimum. Therefore the accurate shape originally i1nparted to the blocks in the mold described above is retained during drying and firing, and the blocks are ready for shipment with out further shaping; after they have once been cast in this rigid and accurate mold.

The characteristic features of this mold, whereby the mold is made of rigid frames in solid contactand containing porous material, may be embodied in various constructions other than that specifically illustrated herein. Thus the frames may be made of wood, suitably hard wood saturated with paraffin or the like to make it non-absorbent and non-warping. and finished to make a wood-to-wood contact. The frames may also be constructed from structural metal shapes, or in a variety of combinations of cast iron, structural iron and wood, which may be readily devised as may be desired. Means other than herein shown may also be employed for holding the sides of the molds together.

A unique feature of our mold is that it is so accurate that the resulting block does not need further shaping. except on the top surface, before shipment and use. This accuracy can preferably be obtained male ing the mold frames of cast iron and machining them'to accurate dimensions.

The rigid frames containing" the porous material protect the porous material from being; chipped or broken in handling and can be easily and rapidly taken apart and re-assemloled. Also, this mold construction 'annot easily be put together an improper manner.

While the"porous'mate'rial is p'r'o all) tected from damage, a maximum amount of the porous material is exposed to the air, resulting in rapid drying. The value of this feature is evident from the fact that at least two-thirds of the water lost in the hardening of a cast block passes entirely through the plaster.

Another feature of great value in this sectional mold construction is that the various parts of the mold may be used with various other parts to make blocks of different sizes. Thus one mold that we have used makes a block which, when burned, is 12 inches thick, 30 inches wide, and 36 inches high. A mold for other blocks 12x2-lx36 inches may include the same ends as the first mold, or a mold for blocks 14x30x36 inches may include the same sides as the first mold, with new ends and a new bottom, and many other examples might be given to show how the side and bottom mold sections, when made in standard sizes, can be assembled to make blocks of different sizes.

Plaster of Paris is well suited for use as our porous mold material, but our invention is not limited to the use of this porous material. Another suitable porous material may consist of Portland cement with a very porous aggregate, the cement being present in relatively small quantity.

Plaster of Paris, sometimes containing fiber, and made into plane sheets has been used heretofore as porous walls against which to cast clay wares. This form is generally known as wall board. (in account of its brittleness and low strength plaster in this form does not last long in service and must. be supported by practically continuous backing, whereas for this purpose rather durable porous walls supported by a minimum of backing are needed.

'0 find that the commercial product which consists of substantially plane sheets of plaster of Paris that contains some fiber. and is covered on each side by an attached sheet of still porous paper, the whole being about three-cighths of an inch thick. is porous and durable, and fulfills the last above mentioned requirement excellently.

Sheets of plaster-like porous material which have greater strength than plaster of Paris, may be permanently or removably used in iron mold frames similar to those des ribed above, or in corresponding wooden mold frames in lieu of plaster of Paris cast in place. lVe also use it with satisfactory results in connection with an alternative mold construction hereinafter described, in which at least part of the porous walls are held in place merely by assemblage of the molds.

The use of porous sheets, as described above, enables us to readily replace any damaged portions of the porous walls without the maintenance of an expensive plaster shop.

A form in which reinforced plaster board may be formed is by the use of chicken wire or similar material embedded within the plaster board. To protect plaster board during handling it may be edged, cased, or otherwise reinforced along its edges with metal or wooden reinforcing.

Still another form in which plaster board may be formed is to use the chicken wire or similar reinforcing material in conjunction with the edge reinforcing.

Another form of porous wall which we find satisfactory for use in ,-.onnection with the various forms of our molds as herein described, consists of rather fine mesh wire cloth, or similar porous cloth like material alone, such as linen, canvas, or the like, or preferably blinded with plastic clay dried in place. either stretched over a frame by itself, or preferably backed by heavier wire screen or similar reinforcing material, preferably rolled wire screen. For blinding purposes the screen that is blinded may itself be quite coarse, the exact limit of usable mesh depending somewhat on the nature of the blinding material used.

Still another form of porous wall which we find satisfactory for our purpose consists of wire screen, the wires of which are of such diameter that in itself the screen will constitute a sutliciently rigid wall so that it will not bulge outward unduly in use. This in turn is covered with plaster of Paris in such a manner that the meshes are tilled, the wires are barely covered, and the porous plaster surtaces are approximately plane. We prefer screen of such proportions that the shaped piece that could pass through a single mesh at right angles to the plane of the screen and extend from the imaginary plane representing one side of the screen thru the screen to the corresponding plane rtaircsenting the other side of the screen is approximately a cube.

For commercial reasons we may use a cheaper form of mold in which the princi pies described above are embodied except that all contacting surfaces are not necessarily metal-toanetal o wood-to-woorl. The construction of the type of mold hereinafter described lends itself readily to the use of plaster-like sheets. ()n account of the nature of the construction of this form of mold, the blocks made therein when dry are not always exactly true to the desired size. However, even these molds yield blocks that require much less cutting than do tank blocks made by the usual methods in vogue today, with corresponding decrease in amount of block material that must be reworked.

Similar to the type of molds first above described. a close approximation to a truly rectangular horizontal section is obtained in these alterna'ive molds by use of a base working ttace whose sides are truly rectangular, said sides serving as bearing surfaces for the side walls. This latter form of mold is also simi ar to the former in that it has rigid side and end walls. However, this term oi mold differs from the preceding, in that the ends do not bear on the sides in a len thwis-ie dirrction ot' the mohl. but are hell Ii' ct position by suitable means such a through bolts and dowel pins. etc, in order to obtain rectangular vertical sections.

in the accompany 11g drawings which show an alternative form oi mold constructe fl in accordance with our invention.

to 'lzl show a mold preferably constructed largely of plaster and wood, except :ror certain supporting and bracing members. shown in Figs. 7 and 8 particularly, We provide legs l9, preferably of iron, in order to support the weight imposed thereupon, that are connected by transversely disposed angle irons 50 and support longitudinally extending angle irons 51 that in turn support transverse wooden sills 62 and form therewith the bottom frame work of the mold. The sills Fa are braced and held in alignment at their outer ends by wooden tie members 53 that are nailed or otherwise secured to the sills *2.

An inspection of Fig. 6 will show that the mold is provided with partitions where by a plurality of blocks may be cast simultaneously. lVithin each compartment termed by partitions we provid a mold bottom (Figs. 7 and 12) that is composed of wooden. slats secured together each end by transverse members and serving as ttrame work for porous material Each of these bottom mold members is of the area indicated in Figs. 6 and 7 and their edges are engaged by the partition, side and end wall portions of the mold. as shown more clearly in Figs. 7 and The end walls comprise wooden - uprights 57 and 58, the end members 57 being pro vided at their tops with extensions 59. as indicated in Figs. 6 and 10, for a purpose to be hereinafter explained. The members 57 and 58 are securec together by cross bars (30 and are faced with sheet rock or similar porous material 61. The members 57 and 58 may be further reintorcet by diagonal braces 62. as shown in 8.

The side walls are composed of wooden uprights (i l that the connected by wooden bars 65 secured thereto in any desired manner, and are faced with plaster-like material. 66.

The partitions are formed oi wooden uprights (37 and 68, the members 67 being provided with upper extensions as shown in Figs. 6 and 7. The members 67 and 68 are eases? secured firmly together by cross pieces 69 and are faced with plaster 70. Jingles T1 are bolted to the upper ends of the uprights 57 and 6"? and have dowel pins for registry with openings in the longitudinal members so that the partition and end wall mem bers may be accurately positioned longitudinally of the side walls of the mold. The openings in the angle 65 are elliptical to allow the bolts 74. to draw the side members up tight and still hold the partition and end members in place by the dowel pins projecting into these openings.

The walls of the mold are held in ass-embled relation in the :tollowing manner. Angle irons 7 are provided at each end of the mold structure both at the top and at the bottom and are drawn toward one another by bolts 72, to hold the end walls lirmly in place.

he side walls are held in place by the transverse bolts 73 and T l. the bolts 73 ex tending through the upper ends of members and GT and through angle irons 65* that are secured to the side walls. The bolts 74: lie within the slots 76 and 77 of the uprights 57 and 67 and through the angles (55", to hold the sides in position against the end walls and the partitions. The partitions 6870 are open at their vpper and lower edges so that air may circulate freely therethrough in vertical direction, thus permitting the moisture that passes through the porous walls 70 to be readily evaporated, notwithstanding the fact that the partitions are engaged at both sides by the clay mate rial which being cast.

Our assemblable molds have the further advantage that when the mold sides are removed the article is left standing upright, on the mold bottom, and a maximum surface is therefore exposed to the air and. the final drying step thereby con'ipleted more quickly than l'ieretofore, where the practice has been to dump the bloclr out of the mold. and permit it to lie. flatwise on the floor. Furthermore. we require much less drying room space.

In view or the many variations of which our invention is capable, it is to be under stood that our invention is not restricted to the exact structure herein shown, but is limited only by the scope of the appended claims.

e claim as our invention:

1. A mold side comprising an open-work relatively rigid frame. provided intermediate its edges with a molding surface of porous plaster-like material.

2. A mold comprising a plurality of side members, each 01" which is or" open-worlr frame construction and covered intermediate its edges with facing 0t plaster-like porous material, the frame members having direct contact with one another at their reiii) spectively adjacent edges, the plaster facing of each frame member extending to a point adjacent to the edges thereof and in proximity to the plaster facing of the adjacent frame member.

3. A mold wall for ceramic material, comprising a rigid open-Work frame faced intermediate its edges by a body of plasterlike porous material held in said frame, the openings in the frame being of such area that passage of moisture through the said porous material is not substantially ob structed.

4t. A mold for ceramic material provided with a wall having an open-work frame faced intermediate its edges by a body of plaster-like porous material held in said frame, the porous portion of the said wall having a relatively great area of surface exposed to the interior of the mold and to the air exteriorly of the mold.

A mold wall comprising a rigid iron frame faced intermediate its edges by a body of plaster-like porous material held in said frame, the iron frame being' of open-work structure and permitting substantially unob structed exposure of the porous surface to the interior of the mold and to the air at the exterior of the mold.

(S. A mold wall comprising a rigid iron frame and a body of plaster of Paris having a binder held in said frame, the iron frame being of open-work structure and permitting substantially unobstructed exposure of the plaster to the interior of the mold and to the air at the exterior of the mold.

7. A mold comprising sides composed of rigid open-work iron frames and plasterlike porous material supported in said frame, the edges of the frame being con structed to permit the mold walls to be assembled in metal-to-metal relation, and said material being so disposed that a substantially continuous porous surface is exposed to material introduced into the mold.

H. A mold comprising sides composed of rigid open-work iron frames and plaster-' like porous material supported in said frames, the edges of the frame beingconstructed to permit the mold walls to be assembled in metalto-met-al relation and the porous material being so disposed that a substantially continuous porous surface is exposed to material introduced into the .mold, the iron frame work having openings of relatively great area to permit substantially unobstructed passage of moisture through the mold walls.

9. A mold wall for glass tank blocks and the like, comprising an open-work supporting frame faced by a sheet of plaster-like porous material.

10. lVIolds for ceramic materials and the like comprising a bottom mold member and side mold members, and clamping means for holding the side wall members in engagement with opposite edges of the bottom mold member.

11. Molds for ceramic materials and the like, comprising a bottom wall of open work frame construction provided with a porous facing intermediate its edges, side wall members of open-work frame construction faced with porous material intermediate their edges, and clamping means for holding the bottom edges of said side frame members in engagement with the edges of said bottom frame member.

12. Molds for ceramic nraterials and the like, comprising a bottom wall of open-work frame construction provided with a porous facing intermediate its edges, oppositely disposed frame members of open-work frame construction faced with porous material intermediate their edges, other oppositely disposed frame members comprising openwork frames faced with porous material intermediate their edges and co-operating with the lirst-nan'ied wall members, and clamping means for holding said frame members in engagement with the bottom wall member.

13. Molds for ceramic materials and the like. comprising a bottom wall of openwork frame construction provided with a porous facing intermediate its edges, side frame members of open-work frame construction faced with porous material intermediate their edges, end frame members comprising open-work frames faced with porous material intermediate their edges. and clamping means for holding said side and end frame members in engagement with the bottom wall member and for holding the adjacent vertical edges of said side and end frame members in engagement.

1%. Molds for ceramic materials and the like comprising a bottom wall having a mold surface whose dimensions are substantially the same as the cross sectional dimensions desired for the finished article, side wall members, and means for detachably securing said members in position with their mold faces substantially in alignment with the adjacent edges of the said bottom wall.

15. Molds for ceramic materials and the like, comprising abottom wall having a mold surface whose dimensions are substantially the same as the cross sectional dimensions desired for the finished article, side and end wall members, means for securing said side and end wall members in position with their mold faces substantially in alignment with the adjacent edges of the said bottom wall and with the vertical edges of said side and end Wall members in abutting engagement with one another.

16. A wall for a block mold comprising arigid frame having side members and spaced intermediate members, a body of lllii porous material extending between said side members and. to the front of the intermediate member, said porous material forming a substantially continuous molding surface.

17. A wall for aceramic mold, comprising an open-work frame, and a body of porone material supported by said frame and reinforced by wire screen therein, the screen having openings therethrough of such diameter and depth that they would be substantially filled by a cube.

18. A mold for glass tank blocks, comprising separable bottom, end and side walls. the bottom wall being of rectangular shape. and the side and end. *alls being held against the edges of said bottom Wall so that the interior of the mold. is of rectangular shape in any horizontal plane.

1.9. A mold for glass tank blocks, comprising separable bottom, side and end walls consisting of open work frames faced with. POIF ous plaster-like material intermediate their edges, the side walls being substantially rectangular, and means for mounting the bottom edges of the side and end walls in alignment. with the edges of the bottom wall, the adjacent vertical edges of the side and end walls being mounted in substantial parallelism so that the mold cavity is of rectangular form in any horizontal plane.

20. A mold wall for glass tank blocks and the like, comprising open-work supporting frames, faced by sheets of plaster-like porous material, at least part of which sheets are held in place by assen'iblage of the mold.

21. A mold wall for ceramic material, comprising a frame, and molding surface consisting of screen or cloth'like porous material secured to said frame, the openings in the porus material being blinded with a porous blinding substance such as plastic clay, and the openings in the frame being of such area that passage of moisture through the said porous material is not substantially obstructed.

2-9.. A mold *all for glass tank blocks and the like, comprising an openwvork support:- ing frame, faced by a sheet of plaster of Paris or similar porous material which is strengthened by tough porous paper at tached to one side thereof.

23. A mold wall for glass tank blocks and the like, comprising a rigid frame and a body of porous n'iaterial held in said frame, the frame being provided with openings of such area that passage of moisture through the said porous material is not substantially obstructed. and means for varying neeae iv viding a covering against one side of the article, which 1s resistant to moisture.

26. A method of drying clay wares 'hich cons s in filling a mold haying porous walls with the material to be dried, to a greater height than is desired. in the d ry article, and removing the upper por ion of the n aterial after the article has ceased shrinki' 27. A mold composed of vertical a 1d horizontal walls. and means for assembling said walls in definite relation at adacent edges, to thereby determine the relative positions of said walls and therefore the dimensions of an article molded thcrebetwcen.

.28. A mold wall for ceramic material. comprising a rigid frame and a molding surface consisting of screen or clotlnlilce porous material stretcheal l1iti.111(-)tl.l21t6 its edges. the openings in the frame being of such area that passage of moisture through the said porous material is not substantially obstructed.

29. The method of treating ceramic articles, which includes the step of initially drying an article while one of its sides is in contact with a porous wall and. another of its sides is. in contact with an object impervious to water.

30. The process of forming an article which consists in introducing wet ceramic material. into a mold cavity whose upper portion is of such greater cross sectional area than the lower portion thereof as to compensate for the greater shrinl zage of that part of the article which is contained in such upper portion.

31. The process of molding wet ceramic material into articles which have greater shrinkage at certain portions thereof than a other portions, which comprises introdiiicing the material into a mold ha ing a cavity of such greater dimension at said certain portions as will compensate for said greater shrinkage.

In testimony whereof we. the said Janns M. LAMBIE and DONALD Ross, have here unto set our hands.

JAMES M. LAMBllL. DONALD W. ROSS.

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