US2068396A - Covering material and process of - Google Patents

Description

Jan. 19, 1937. s. w. CHAFFEE 2,068,395

COVERING MATERIAL AND PROCESS OF MAKING THE SAME Filed April 19, 1933 v 2 Sheets-Shee, l

BYMScSpl/nm.

ATTORNEY Jan. 19, 1937.

S. W. CHAFFEE OVERING MATERIAL AND PROCESS OF MAKING THE SAME 2 Sheets-Sheet 2 Filed April 19, 1933 SNN INVENT'OR STEWART W CHA/T55 Wfpmm' hal lawns. I.

ATTORNEY Patented Jan. 19, 1937 UNITED STATS rATENT OFFICEv COVERING MATERIAL AND PROCESS F MAKING THE SAME Application April 19, 1933, Serial No. 666,832

35 Claims.

This invention relates to covering units and more especially to units simulating shingles of natural stone or' other natural materials. More particularly the invention relates to covering units simulating shingles of natural materials, especially stone, having a laminar structure such as slate and the like.

Covering units oi the type comprising a base upon which is bound by an adhesive a surfacing mi layer of mineral material are commonly used as substitutes for slate singles and other covering materials of natural stone or other natural products. Such mineral surface covering units heretofore to a great extent have lacked the charm acteristic features of the natural product. Although granular slate has been used for the surfacing layer, due to the methods of manufacture heretofore used a monotonous uniformity both of surface character and of outline have prevented the obtaining of complete simulation of the natural units. While some attempts have been made to provide outlines of different regular and irregular forms in order to break the monotony of the units in the roof or arranged upon a surface to be covered, simulation of the structure and surface of the stone, such as the laminar structure of slate, in such covering units has not been successfully accomplished.

It is an object of the present invention not only 30 to provide for the simulation of the irregular outline of the natural units but also to provide the simulation of the irregular surface characterist-ics that is, the depressions and other unevennesses of the surface. Moreover, particularly in the simulation of shingles of natural stone, such as slate, it is an object of the invention to simulate the laminar structure of the slate and the form of the edge of such natural slates which are pron duced by the breaking or cutting of the slates re- 4o sulting in cleavage of the slate along the laminar layers. In said natural stones there is thus produced a kind of stepped edge'following the natural cleavage lines of the laminae. Also the cleavage of the natural stones such as slate may remove a portion of a laminar layer upon the surface of the shingle to expose a pOtO-n 0f 2i` Sub-jacent layer. The invention also produces a simulation of units having such exposed areas and of the high and low light effects resulting from each expo-sed areas and depressions.

The invention particularly is applicable to covering units constructed with a base, usually of flexible material, having thereon a plastic ccating or a mastic material such as asphalt acting as an adhesive and usually as a. Weather resisting coating. Said coating usually is surfaced with a granular surfacing material such as granular slate. In a simple embodiment of the invention I provide upon one or more edges of the covering unit a marginal portion which may be of contrasting character or of greater depth of color with respect to the main portion of the surface to be exposed of the unit. Said marginal surface, however, according to the invention, is so formed as to provide depressions or steps of irregular outline and of irregular relationship to each other and with respect to the edge of the base of the unit so as to simulate the laminar steps ofthe natural stone. In general such steps have at least a part of theirsuriace depressed below the face to be exposed of the covering. However, said marginal surface may be provided with depres sions of irregular outline and in iregular relation to each other and to the edge of the unit, which depressions are not in. the form of steps but are in-dentations of greater or less depth in the face surface of said margin 'but have their length extending along the edge of the unit.

In a simple form of the invention in connec` tion with units having the asphalt coating and a slate surfacing adhering thereto I providefor removal or depression of the slate surfacing upon the marginal portions mentioned above so as to leave exposed upon said marginal portions the asphalt or other adhesive coating. Thus I proo vide a contrast between the main mineral sur'- faced portion of the unit and said marginal por-I tions. In such a form not only does the contrast exist between the depth of color of the slate suru facing applied upon the unit and the asphalt but also between the surface character of the face of the unit and the irregular surface char-l acter of the marginal portions as provided by the steps or indentaticns formed in the asphalt and simulating the laminae. However, instead -of merely exposing the dark' color of the adhesive I may apply to said depressed areas, either before or after forming the depressions, colored materials to produce the desired contrast. The invenztion now may be understood by reference to the drawings in connection with the following description: l

Figure 1 represents a face View of an individual shingle embodying 4the invention.

Figure 2 represents a modified form of the invention as `embodied in shingle strips.

Figure 3 represents a cross section of line 3-3 of Figure 1. i Figure 4 represents a cross section of line 4 4/ of Figure 2.

Figure 5 is a section of a double surfaced covering unit before being subjected to the process of the invention.

Figure 6 represents a section on line B--G of Figure 2 of the double surfaced covering unit after being subjected to the process of the invention.

Figure '7 shows a die and cutting knife for forming the units of the invention.

Figure 8 shows a stop device of irregular contour according to the invention with an element of irregular outline abutted thereagainst.

Figure 9 shows the stop of the invention with the element abutted thereagainst in a different position. l

In Figure 1 and Figure 3 the covering unit has its outer edge Iv to be exposed formed with Steps along a marginal portion of the face adjacent said edge, said steps being of irregular outline and being formed as described above by removal of portions of the asphalt coating 2 or by compressing portions of said coating along said marginal surface. If portions of asphalt coating 2 are removed the steps may be formed as at 3 with a relatively thin layer of coating and at 4 with a slightly thicker layer, the levels of both being below that of the surface 5 of the asphalt coating 2 upo-n which is applied the granular material 6. The steps, however, may be formed by means of a die, such as that shown in Figure l for pressing upon the margin of the unit. The die is provided with portions depressed or raised relative to each other so that when pressed upon the margin of the unit the asphalt coating will be compressed to different levels with respect to the base 'l and with respect to the surface 5 of the asphalt coating 2. The surfacing material in such case conveniently may be applied after the formation of the steps of asphalt coating 2.

The steps, however, may be formed after the surfacing 6 has been applied on the coating 2 of the unit. This may be done by removal of marginal portions of the coating 2 together with the surfacing material adhering to said portions of the coating. A convenient way, however, of producing the steps is to embed the granular material in the asphalt coating to such a depth as to leave the asphalt coating exposed for the most part or to entirely submerge the granules in the asphalt coating or even to press them down into the base as may be seen at the left hand of Figure 4. The granules l in the outer step Il are embedded in the relatively thin asphalt coating and partially in the base 1. The granules I2 are embedded in the asphalt coating but not to such a depth as to be partly embedded in the base 1. Within the scope of the invention the granules may be embedded to varying degrees and the form of the steps as shown in the sections in Figures 3, 4 and 6 may be varied to accentuate the laminar form and the shadow effects produced by shingles of natural stone or slate. Additional granules of contrasting color may be embedded in the areas of said steps or depressions.

In general the method of producing the simulation of the laminar form of edge by pressing. as with a die, is more convenient for shingle strips having a plurality of tabs to be exposed as shown in Figure 2, since a die 32 may be constructed with portions such as 33, 34 and 35 shown in Figure 7 to press the asphalt upon the margins along the lower edge; such portions may also be provided in the same die simultaneously to press the side edges of a tab or of a plurality of tabs. Moreover when the irregularities of the surface to be exposed of the unit of natural stone or slate are to be simulated either upon an individual shingle or a shingle strip the die may be so formed as to include portions 40 and 4I, Figure '7, which will press upon areas of the surface to be exposed of the unit or of the tab to depress the asphalt coating or to depress and embed either partially or in some instances wholly the granular surfacing material 6 applied upon said coating. Such an area of depression is shown in Figure 2 at 20. Such a depression area also may be seen in section at 20 in Figure 6 where the outermost layer of granules is depressed and partially embedded in the layers of adhesive coating. The areas surrounding such va depression area also may be made of irregular height, by the application of a die having portions 45 of suitable form, without markedly embedding the granules in the adhesive coating to leave exposed portions of said coating, although if desired the degree of embedding in these portions may be carried out in areas of greater or less extent to bring about the simulation of the laminar construction of the stone. Moreover, the laminar structure may be emphasized in such areas by providing steps 21 upon the marginal areas surrounding or adjacent a depression such as 20. These steps 21 may be formed by portions 42 on the die 32. However, if desired such depressions 20 and any steps or indentations related thereto maybe produced by removal of the adhesive or mastic coating or by removal of the granular material or both.

In Figure is shown a cross section of a covering material or of a covering unit constructed with a base 1 having an adhesive coating 2 thereon and a layer of granular surfacing material 6 adhering thereto. Upon said surfacing is applied a second adhesive coating 22 having, adhering to said second adhesive coating, a second layer of surfacing material 26. Such a covering material or unit is produced by methods which form no part of the present invention. The invention finds particular application in connection with such a covering material because of the increased thickness of such material and because by producing the steps upon the edge of the unit formed from such a material a greater number of steps may be produced and the characteristic laminar construction of thick shingles of natural stone may be more faithfully simulated.

As may be seen in Figure 6, which illustrates a stepped edge formed by compressing the edge of such a double coated covering material and embedding the granules in the asphalt coatings, a considerable thickness of the laminar material is simulated and the shingle, when seen from a position such as it would have when laid in the roof, appears thicker than it actually is. Moreover, the contour of the stepped portions as shown at 23, 24 and 25 may be varied to provide irregularity or the appearance of lines of cleavage of the laminae which are not parallel to the base and as suggested above, such contours within the scope of the invention may be those provided by indentations having a lineal extent along the edge or along a depressed'area 2B. Such irregularities are consistent with variations which take place in the natural stone and, especially when combined with depressions such as have been described above and are shown in Figure 6 at 20, assist in producing the simulation of a stone of irregular cleavage lines and of irregular surface resulting from such virregular cleavage lines. If desired, however, by suitable means such as scrapers or other devices for removing the adhesivecoating the steps 23, 24 and 25 may be formed in the manner suggested in connection with Figure 1 instead of embedding the granules as illustrated in Figure 6.

As has been suggested above, the granules of mineral surfaced covering materials utilized in the invention may be depressed or embedded in the asphalt coatings only to such degree as to leave them partially exposed but at the same time forming the steps or the depressions 2i) in the manner described. It is also within the scope of the invention to form the steps or the depressions and then to apply thereto granular material either of the same size, color and granular character as utilized upon the main surface of the covering unit or to apply to said marginal stepped surfaces or to said depressions granular or other material of contrasting character but suitable for adhering to and assisting in holding the asphalt coating as does the granular material upon the main surface of the unit, Thus I may obtain not only the simulation of the laminar structure of natural stone but also may maintain or .produce the simulation of the surface character of such laminar structure of the natural stone. One of the characteristics of the natural stone thus produced is a shadow effect due to the difference in surface level or in angle of such portions so that they appear to the eye to have a dilerent shade or depth of color. Thus there is produced a simulation of the contrasts existing in the natural stone such as slate when formed into shingles.

In order to accentuate the simulation of the shadow formed by natural stones or slates in overlapping arrangement, especially when the effect of relatively thick materials is desired I may provide a relatively narrow depression 3K3 as shown in Figures 2 and 6 at a point removed from the edge to be exposed of the unit a distance slightly less than the length of the exposed face of the unit. Said depression 3D has its length extending generally parallel to the edge to be exposed of the unit and conforms substantially to the outline of said exposed edge. Thus the depression 3B extends transversely across the width of the unit shown in Figure 2 and is so related to the edge of an overlapping unit as to lie in the area of the shadow of said overlapping unit upon a subjacent unit. If desired I also may depress `the overlapping portion of a unit along a line or area 3| upon which will fall the cut-out in a strip or the space between adjacent individual units so that the shadow effect is carried out for the lengthwise edges to be exposed of the overlapping tabs or units.

In order to produce the depressions 30 and 3| conveniently I may so form the die used to produce the depressions 20 and to form the steps 23, 24 and 25 in the marginal portions of the face of the unit that said depressions 36 and 3| are also formed upon the application of the die to the surface of the unit` For example, the depression 30 may be produced by the portion 39 and the depression 3| may be produced by the portion 4| of the die illustrated in Figure 7. However, I may produce said depressions 3Q and 3| by any other convenient means, such as removal of a portion of the coating or of the surfacing or of both.

In asphalt coated mineral surfaced coverings the Vmethod of embeddingmthe granular mineral.

material in the asphalt coating pro-vides upon the areas 30 and 3| a surface of contrasting appearanceand of such a dark color as to provide the simulation of a shadow.

To produce covering units or shingles of regular or of irregular outline embodying the features of my invention above described for simulation of the laminar structure of the natural material without excessive waste of the material and with as few operations as possible so as to reduce the cost of manufacture I propose to cut the outline of the shingles in the same operation or such closely related operations that extra handling of the material is avoided and so that, when the process used to form the irregular surface and the steps to simulate the laminar structure are completed, the shingles or covering units also will have their proper completed form and outline.

According to one method of producing units having the form of the exposed surface and of the stepped edge of the invention and having the desired outline I propose to combine with the die, shown in Figure 7 and described above, a knife or cutting edge 56 which in the particular embodiment illustrated surrounds the die forming the tab and is of such dimensions and extent and is so arranged with respect to the die as to cut the exposed edge and the side edges of the tab. In the particular form illustrated the edge '5U would be sc formed as to produce the irregular outline for the end of the tab shown in Figure 2. The side edges of the tab may be cut `by knives or cutting edges 5| which may be straight, as shown in Figure 2 or, if an irregular edge is desired, also may be of irregular outline similarly to that of the knife 5u. The depth of the cutting edges 52 and 53 of these knives will be such with respect to the portions 33, 34, 35, 4|), 4|, 42 and 45 of the die that when the die is pressed upon the surface of the tab of the shingle strip to a proper depth tc form the steps and depressions above described, the edges 52 and 53 of the knives: .Fili and 5| will pass through the base material and sever the shingle or unit from the sheet of the material of which it is made. n

While the combined die and cutting edge illus trated in Figure '7 have been shown and described in connection with one tab of the strip shingle illustrated in Figure 2, it will be apparent that this method of simultaneously producing the formed surface of the shingle and a straight or irregular edge as desired may also be utilized in forming individual units such as that shown in Figure l. It will now be understood, in forming such an individual unit, whether or rnot the edges thereof vare to be made straight or are to be of irregular outline such as the exposed edge of the tab of Figure 2, that the base sheet of material may be cut without waste since the cut forming one shingle also may form the edge of another shingle.

Certain methods heretofore have been used for cutting shingles without waste and in the cutting of shingle strips having cut-outs or recesses such as those formed in the strip illustrated in Figure 2. Thesev methods'also have provided for the removal of the piece of the base material cut out between two adjacent tabs. For example, after cutting the exposed edge and side edges of the tabs forming the iinished edges of a succeeding unit, a fly-knife has been used to cut oif the piece of the base material extending from the back of the strip, which piece has been formed by the cutting of the side edges of the tabs. However, according to the ymethod I propose of combined die-pressing and cutting of the shingles or units, I may provide a knife of suitable form to cut off such projecting p-iece of base material simultaneously with the pressing and cutting of the shingle and thus nish at once the edge to be exposed of the unit and the rear edge thereof.

Various modifications of the method may be made. For example, the combined die and knives may be mounted on a roll and the sheet passed under the roll. The sheet is thus substantially simultaneously cut and formed upon its surface just as when a die such as illustrated in Figure 7 is mounted in a suitable holder and pressed upon the sheet of covering material by a reciprocating motion such as occurs in the usual press.

While such methods as have been referred to above have been used for cutting the edges to be exposed of a covering unit or of a shingle in order to prevent Waste and to effect a saving in the cost of manufacture by avoiding extra operations, I provide according to my invention for obtaining these advantages while at the same time avoiding the additional operations which otherwise would be necessary in order to produce the formed surface and the steps and the recesses and depressions by means of which I obtain the simulation of the laminar structure. Thus, by my invention, I am able not only to produce a unit having features not heretofore known in the art but by the method of my invention utilizing the simultaneous or substantially simultaneous cutting and forming of the base material I am able to produce such units without substantial increase in either the cost of manufacturing operations or of waste of the material from which the units are to be made.

A further feature of my invention is obtained by the method of pressing the mastic coating along the edge of the unit to form the steps or depressions. By providing a suitable thickness of said coating and especially by suitably forming the die with respect to the edge to be pressed of the unit I may squeeze a portion of the asphalt over said edge to cover and seal the base material. Particularly when said base material is of fibrous structure such as roofing felt and asphalt, for example, is used as the mastic coating I thus provide a seal against the Weather for the edge of the felt which has been cut to form the shingle or the tab of the unit. Moreover, by squeezing the mastic coating to greater or less degree or by providing a die of irregular form I may produce an irregular edge while at the same time effecting the sealing.

Coverings embodying my invention may have different forms and shapes in the individual units shown in Figure l or of the tabs in the strips such as shown in Figure 2. The stepped form of edge may be provided on shingles of hexagonal or octagonal or any other regular form such as are utilized in slate shingles or other covering units of natural stone, or said individual units or said tabs may be provided with irregular outlines and may be irregularly related to each other in an assembly or in a strip so as to produce in the covering material assembled upon a surface to be covered, such as a roof, the appearance of roughly cut irregularly dimensioned units of natural stone or other material of laminar structure.

The invention is not limited to the particular shapes of covering units illustrated and the process of the invention may be applied to any material having a plastic or mastic body deformable or removable to provide the depressions or the steps. For example, I may take a mass of cementitious material in a plastic state and in a form such as will provide a covering or covering unit and may press the surfaces thereof, as with a die such as that shown in Figure '7, to produce in the face of said mass the depressions or the steps which constitute an important feature of the invention as described above. When said cementitious mass is set there is produced a stiff covering or covering unit upon the surface of which will be simulated the laminar structure of a natural material as described above. By subjecting said mass of cementitious material to a high pressure at the time of applying the die to the face thereof, I may produce a hard and dense covering or covering element which will have the surface appearance of a natural stone such as slate and Will be rigid and as well wear and Weather resisting as is the natural material. To produce such coverings or covering units in a practical way I may mount a plurality of dies in a stack with the plastic masses placed therebetween. In such an arrangement it is possible to bring pressure upon the stack and apply the pressure equally to all of the dies and thus to all of the plastic masses placed therebetween.

In order to provide the contrasts described above between the main face of the unit and the edge thereof or the portions providing the steps or depressions, I may apply to the face of the shingle upon either the surfaces which are depressed and upon the steps or upon the raised portions of the surface produced by the die a layer of cementitious material of a character Aor color contrasting to that of the other of these two portions. It is a feature of this phase of my invention that I may apply this layer of cementitious material not only with irregular contour but With such roughness or smoothness of surface as will characterize the particular laminar structure being simulated.

Thus, by way of illustration, in producing units to simulate slates I may use a cementitious material of somewhat darker color, for example, than that from which the body or mass of the unit is made, and may apply said darker cementitious material to the portions which are depressed, that is the portions such as the area 2Q shown in Figures 2 and 6 and the steps formed at the edge of the unit as described above. I may thus produce in a covering or unit made or composed of cementitious material effects similar to those produced in that phase of my invention relating to covering units having a base material and a coating of asphalt or other mastic or adhesive on the surface thereof, in which coating the granular surfacing material may be wholly or partially embedded to provide upon said steps or depressions surfaces contrasting With the face of the covering.

Moreover, I may use a combination of said phases of my invention by applying to a covering having a base, upon which may be applied an adhesive coating, a layer of cement. Said layer of cement may be applied to the main face of the covering either alone or in addition to granular surfacing material applied on said face, thus to accentuate the irregular character of said face if so desired. I may apply the cementitious layer irregularly to the surface or I may build up one portion of the surface in relation to another to produce the high or raised portions of the face of the covering.

On the other hand said layer may be applied to the depressed areas and to the steps in order to provide thereon a protective covering, which ment.

Vbe applied to the steps or depressions so that layer may be of co-ntrasting character or color to the granular surfacing upon the main face of the covering or the unit, thus to carry out the shadow effect and the light and shade effects produced by said depressions and steps. For example, in a covering having a felt base and a coating of asphalt thereon, upon which coating is applied a surfacing layer of granular mineral material such as slate, I may form the steps by embedding the granules in the asphalt coating or by removal of said granules and, if necessary, a portion of said coating as hereinabove described. I may then apply to said steps or depressions a layer of cementitious material preferably of darker color than the granular material adhering to the face of the covering, thus not only to protect said steps and depressions, especially when a portion of the asphalt coating has been removed in producing said steps and depressions, but also to produce the shadow effect and the simulation of the laminar structure above mentioned.

A convenient means of applying the cement layer, particularly when it is desired to build up the areas which are intended to be `raised on the face of the covering, is afforded in the so called cement gun, that is a type of sprayer, whereby the amount of material applied may be controlled and its location may be distributed as desired. This distribution may be regular and smooth or it may be irregular and Without the smoo-th effect Which is secured when cementitious material is applied by means of a trowel or similar instru- By this means a light coating only may these portions of the covering will not be built up to any great extent. Thus I may secure the protection upon the steps and depressions afforded by the cementitious material but I may avoid detracting from the effect produced by said steps or depressions in simulation of the laminar structure as has been hereinabove set forth.

In units comprising a mastic material or composed of a base having a mastic coating thereon such as asphalt when, to produce the depressions or steps, portions of the mastic material are removed and also in tho-se units upon which a surfacing material is applied to the mastic material or coating when such surfacing material is embedded in the mastic material, said mastic material or coating is left exposed and without the protection afforded by the granular surfacing material. In order to maintain the contrast produced by this form of the invention and to maintain the simulation of the laminar structure as described above while at the same time protecting the mastic material both upon the face of the unit and upon the edge surface thereof I may apply to said unsurfaced portions and to said edge surface a film of protective material, such as a paint, which is of such character as to be without solven or other deleterious effect upon the mastic material and which preferably is transparent or translucent to such a degree that the surface of the mastic coating may be seen therethrough. Thus the contrast between the surfaces of the depressions and steps with respect to the surfaced face of the covering may be maintained. As materials for this protective lm I propose such paints or lacquers as will adhere to. the masticcoating, especially to asphalt commonly used in covering units, and Which will not dissolve or otherwise chemically or physically re- `act with the mastic coating to any marked degree. Such paints may be bituminous paints or some of the varnishes and such laquers may for example be those composed of synthetic resins.

Either of such materials can be obtained of a consistency which Will permit of their being sprayed upon the surface by an ordinary paint spraying device. The lacquers of synthetic resins and some varnishes afford the advantage that they may be obtained in transp-arent or translucent form which thus permits the color or depth of shade of the portions upon which they are applied to be seen through a film thereof. More-over, when such laquers are used, if desired, a nlm thereof may be applied to the whole surface of the covering as the transparent quality will not impair the appearance of either the surfaced or unsurfaced portion of the face of the covering and the contrast between said portions will be maintained. As has been stated above, it is desirable also to cover the edge surface of the covering material especially when in producing the element or unit said material has been cut through and the edge of the base material is thus exposed. By spraying the paint or lacquerv upon said edge, preferably at the time of applying the film to the depressions or to the Whole face of the covering as mentioned above, the face of the edge, that is, the edge surface of the base material may be suitably protected.

According to another phase of my invention I propose to combine with the die described above and shown in Figure '7, which die is used for forming the depressions in the surface of the covering, a stop so formed with respect to the covering, and particularly with respect to an edge thereof, that variations in the form of the depressions applied to the face of the covering may be obtained without the use of separate dies. Thus I avoid the necessity of using a large number of dies to produce different forms of the depressed surfaces and of the irregular contours of the face of the units and I also make possible a convenient method by which to produce the variation in the surface character without the necessity of changing the dies.

As shown in Figures 8 and 9, I may use a stop 6B provided upon the face of said stop with an irregular contour 6|. The stop is so set with respect to the portions 33, 34, 35, etc. of the dies which produce the depressions in the covering element 63 that the edge 64 of said covering element may be abutted against said irregular contour 6| of the stop to bring the element into position with respect to said portions but permitting variation of said positions. Figures 8 and 9 illustrate merely one embodiment of this phase of the invention according to which covering el-ements having the edges thereof formed in irregular outline are abutted against the irregular contour of the stop. The gures may be taken to show diagrammatically like elements in different lateral positions with respect to said stop. The shaded areas 66, 6T and 68 respectively are the steps produced by the portions 33, 34, 35 of the die. It Will be noted that these areas are of different shape in the two figures and also that some portions of the die are in such position as not to become impressed on the element.

It now will be understood that when covering elem-ents having edges of different irregular outlines are abutted against said irregular stop, the faces of the covering elements also become differently positioned with respect to the high and loW portions 33, 34, 35 and 45 of the die so that different high and low portions are applied to the face of the different elements. Not only will this be true due to the fact that, as above explained, certain portions of the die will be without contact with material of the covering along the edge thereof while other portions of the die will be in contact with said material, but also because of the differences in outline of the different covering elements said elements will be differently positioned with respect to the surface of the die in a direction transversely to the face 6l of the stop 60 when the edges 64 of the elements are set thereagainst.

This difference of transverse position, however, is obtained also with elements of the same outline when placed in different lateral positions along the stop. Thus in order to produce further variations I may provide a die and a corresponding stop of irregular contour of such dimensions in a direction along the face of the stop as to be wider than the Width of the portion of the element upon which the depressions or other face contours are to be formed. Then in successively setting different elements against the stop I may position said different elements differently in a direction along the face of said stop. When said elements have edges of irregular outline, as shown in Figures 8 and 9, it will be clear that different points of the irregular outline will come in contact with different points upon the face of the stop of irregular contour.

This will be true whether or not the different elements have edges formed in the same or in different outlines. There will thus be impressed upon the face of the element not only a different lateral portion of the face of the die due to the different position of the element in a direction along the face of the stop, but also the element will become positioned differently with respect to the die in a direction transversely to the face of the stop. Moreover, in either case different portions of the face at the edge of the elements will be pressed upon by the die and thus the depressions or steps formed upon said edges will be of different outline and extent as shown in Figures 8 and 9.

While in the above description reference has been made only to the illustrated embodiment showing elements having edges of irregular outline set against stops of irregular contour, within the scope of my invention I may use a stop of irregular contour to produce different depressions, especially diierences in the form of the steps upon the edge of the element when said edge of the element is a straight edge or other edge of regular outline. It will be understood that, by shifting an element having a straight edge, for example, along a stop having a face of irregular contour, not only different portions of the face of the die both laterally of the element, i. e., in a direction along said face of the stop, and also transversely to said face will be impressed upon the element but also that different forms and outlines of the depressions or steps upon the face at the edge of the element will be produced due to the diierence in position transversely of the face of the stop. As a simple example, in a covering unit, as shown in Figure 1, having a straight edge and surfaced in the usual manner with granular surfacing material and using a die having no portions to produce depressions in the main portion of the face of such an element I may vary the depressions formed in the edge of said element by suitably positioning said di-e in relation to an irregular stop against which to set the regular edge of the element. I

also may produce the variation in the depressions when using a stop of regular form when combined With a die of suicient lateral dimension that successive elements may be set thereunder in diiTer-ent lateral positions along the stop.

It will now be clear that a large number of dies having diierent designs thereon, each design differing from the others in greater or less degree, and providing for different forms of depressions and contours of the face of the covering, will not be necessary in order to secure the desired variety of surface character which occurs in natural materials of laminar structure. Thus I avoid large expense for dies and also the expense of handling and changing said die to get different effects. By combining the variations in position both laterally and transversely of the stop and by varying the form of the stop I may secure suiiicient variation in a die having a lateral extent not excessively greater than that necessary for application to a single element, for example not greater than the lateral extent of one and one-half or two elements. The lateral extent of the die and of the stop Will vary with the size and form of the elements, the surface of which is to be pressed. Such variations are within the scope of my invention.

Having thus described my invention, what I claim is:

1. A covering simulating a natural material of laminar structure, said covering being formed upon an area of the face to be exposed thereof With a depression of deiined but irregular outline and of a form and depth simulative of the lamina of the structure.

2. A covering simulating a natural material of laminar structure, said covering being formed along a marginal portion of an area of the face to be exposed thereof with a step of irregular outline, said step having at least a part of its surface below the face to be exposed of said covering and being formed to simulate the lamina of the structure.

3. A covering simulating a natural material of laminar structure which comprises a base having a plastic coating thereon, the marginal portions of said coating upon an area to be exposed of the covering being formed with at least a part of their surface depressed below the face to be exposed of said covering and forming edges simulatively defining the lamina of the structure.

4. A covering unit simulating a shingle of natural stone having a laminar structure comprising a base having an adhesive coating thereon and a layer of surfacing material adhering to said coating, the marginal portions of said coating adjacent an edge to be exposed of the unit being formed with a step at such a depth below the surface of the unit and in such edge defining relation thereto as to simulate a lamina of the natural stone, the surface of said step being of contrasting appearance to the surface of the unit.

5. A covering unit simulating a stone having a laminar structure which comprises a base having bound thereto by an adhesive coating a granular surfacing material, the marginal portions of said granular surfacing material adjacent the edge to be exposed of the unit being embedded in said adhesive coat'mg to a depth to produce a step upon said marginal portions lower than the main surface of the unit and with edges simulatively dening the laminar structure.

6. A covering u nit according to claim 2 having a plurality of steps extending generally along the edge of the unit.

7. A covering unit according to claim 3 having a portion of the main surface to -be exposed of the unit depressed with respect to the remainder of said surface to a depth corresponding to the depth of a lamina and in an outline to simulat-e a portion of the superimposed lamina.

8. A covering unit according to claim 3 in which granular surfacing material is irregularly embedded in the plastic coating to greater or less degree to simulate the irregular surfaces of the natural stone.

9. A covering unit according to claim 3 in which granular surfacing material is irregularly embedded in the plastic coating to greater or less degree to simulate the irregular surfaces of the natural stone, some of said granules being substantially completely embedded in said coating to expose said coating in areas contrasting with the main granular surface of the unit to simulate the natural stone having portions of the outer lamina broken away to expose an underlying lamina.

l0. The process of producing a covering to simulate natural material of laminar structure which comprises forming upon an area to be exposed of said covering a depression having at least a part of its surface at a depth below the surface to be exposed of said covering and of such defined form as to be simulative of the lamina of the structure.

ll. The process of producing a covering to simulate a material of laminar structure which comprises applying upon a base a coating of plastic material, forming said coating upon the marginal portions of an area to be exposed of the unit so as to provide a depression having at least a part of its surface below the main surface to be exposed of the unit and of such defined edge formation as to simulate the laminar structure.

12,The process of producing a covering to simulate a natural stone of laminar structure which comprises applying upon a base ay coating of adhesive, applying upon said coating over the whole face to be exposed of said covering a layer of surfacing material, pressing a marginal portion of said face adjacent an -edge to be exposed thereof so as tofembed the surfacing material upon said marginal portion in said coating to a greater degree than upon the general surface of said face to be exposed and so as to form at least one step' in said marginal portion having at r lleast a part of its surface below the surface of said remaining portion and of a form simultatively to denne a lamina of the structure.

i3. The process of producing a covering to simulate a natural stone of laminar structure which comprises applying upon a base a coating cf adhesive, applying upon said coating over the whole face to be exposed of said covering a layer of surfacing material, pressing a marginal portion of said face adjacent an edge to be exposed thereof so as to embed the surfacing material upon said marginal portion in said coating to a greater degree than upon the general surface of said face to be exposed and so as to form at least one step in said marginal portion having at least a part of its surface below the surface of said remaining portion and of a. form simulatively to define a lamina cf the structure, said surfacing material being depressed in said adhesive coating upon said marginal surfaces to an extent to expose the coating sufficiently to produce a contrast in the appearance of said marginal surface with the main face to be exposed of the covering.

14. Process of producing a covering unit to simulate a shingle of natural stone having a laminar structure which comprises forming upon the marginal surface adjacent an` edge to be exposed of said unit at least one step having its surface below that of the general surface to be exposed of the unit, forming within the area of said surface to be exposed of the unit a depression below said general surface, and forming the remainder of said surface to be exposed of the unit with irregular contour to simulate the irregular surfaces of natural stone produced by cleavage along the laminae thereof, said step and said depression being of a depth and having theA outline boundaries thereof so formed as to define the lamina of the structure.

15. A covering for laying in overlapping arrangement and simulating natural stone of laminar structure, said covering being formed along a marginal portion adjacent an edge to be expo-sed thereof with a depression of such depth and form as to be simulative of the laminar structure, said covering having a depression in the face thereof having its length extending across said face in a direction generally parallel to said edge to be exposed and removed therefrom a distance slightly less than the extent of the face to be exposed in the direction transversely of said edge whereby when the edge to be exposed of an overlapping covering is laid adjacent said depression in the face of a subjacent covering said depression accentuates the shadow of said adjacent exposed edge.

15. Process of producing a covering element to simulate a unit of natural material of laminar structure which comprises pressing the material of the covering unit to provide in an area upon the face thereof a depression of a depth of such defined form as to simulate the depth and form of a lamina of the structure, and cutting said covering material in outlines simulative of the natural unit.

17. The method of sealing the edge of a covering having a mastic coating upon the face thereof which comprises pressing the marginal portion of said coating upon the face of the covering adjacent said edge so as to cause a portion of the coating to extrude beyond said edge of the covering and molding said extruded coating to cover the edge surface of the covering.

18. Process of producing a covering element to simulate a unit of natural material of laminar structure which comprises shaping the element with an edge of irregular outline, setting said edge against a stop of irregular form, and pressing the face of the element to produce therein depressions which are irregularly related to said edge of irregular outline.

19. Process of producing a plurality of dissimilar covering elements to simulate units of natural material of laminar structure and dissimilar outline which comprises shaping the elements with edges of dissimilar outline, setting said dissimilar edges successively against a stop and pressing the faces of the elements to produce depressions in said faces whereby the form. of the depressions on the different elements is different.

20. In combination with a die for making depressions in the face of an element having an edge of defined outline, a stop against which said edge of the element may be set to position the element with respect to the die, the facey of said stop against which said edge of the element is set being irregular, whereby When separate elements are set thereagainst at different positions along the face different portions of the die in a direction transversely to said face of the stop may be impressed upon the element.

21. A covering comprising a mastic material, portions of the surface of said mastic material being covered with alayer of surfacing material of contrasting appearance to said mastic material, the unsurfaced portions of said mastic material having applied thereto a protective film of a character to preserve the contrasting appearance.

22. A covering simulating a natural material of laminar structure comprising a mastic material, portions of the surface of said mastic material being covered with a layer of granular surfacing material of contrasting appearance to said mastic material, the unsurfaced portion of the surface of said mastic material being depressed in simulation of the laminar structure and having applied thereto a protective film of a character to preserve the contrasting appearance.

23. A covering according to claim 1 having granular surfacing material adhering to the face thereof and a layer of cement of contrasting appearance to said surfacing and adhering to said covering in said depression.

24. A covering according to claim 1 having applied to the face thereof a layer of cement of irregular depth to produce the depressions and an irregular surface upon said face to be exposed of the covering.

25. Process of surfacing a covering to simulate natural material of laminar structure Which comprises superimposing upon a base material a layer of oementitious material, and forming said layer to present a surface of irregular contour with depressions therein of a depth and outline simulative of the laminar structure.

26. Process according to claim 25 in Which the irregular contour is produced by spraying a nonuniform layer of oementitious material upon said surface.

27. Process of producing a covering to simulate natural material of laminar structure which comprises impressing upon a mass of oementitious material in a plastic state a form to provide a depression of a depth and outline simulative of the lamina of the natural material, and subjecting said mass to pressure prior to setting.

28. Process of producing a covering to simulate natural material of laminar structure which comprises stacking a plurality of masses of cementitious material in a plastic state between dies of a form to produce depressions in the faces of said masses of a depth and outline to simulate the laminae of the natural material, and bringing pressure upon said stacked masses simultaneously to compress the same and to produce the depressions prior to setting of the oementitious material thereof.

29. Process of varying the impression made by a die upon the face of a succession of elements which comprises setting an element With an edge thereof against the face of a stop, said face of said stop being of irregular contour, pressing the face of said element with said die, setting a second element with an edge thereof against the face of said stop in a different position along the face of said stop to vary in a direction transversely of said face the position of said second element with respect to the position of the first element whereby said die contacts said second element in a diierent portion thereof than the rst element.

30. Process of producing covering elements which comprises forming upon each of a plurality of the elements an edge With an outline having projections and indentations, said edge in different elements being dissimilar, successively setting said elements with said edge thereof against a stop formed in an outline having projections and indentations, and pressing said elements to produce marks thereon in dissimilar relation to said edge of the elements in different elements.

31. Process of producing a covering element which comp-rises pressing said element upon a given area thereof With a die formed to produce irregular depressions in the element, shifting said element to a different position under the die, and again pressing the element to extend the formationvof irregular depressions in the element.

32. Process of producing a covering element which comprises setting the edge of the element against a stop formed With an outline having projections and indentations and in indiscriminate relation to said outline, and pressing the element in a predetermined relation to the stop to produce on the element marks in indiscriminate relation to the edge thereof.

33. Process of producing a covering element which comprises forming an edge upon the element With an outline having projections and indentations, setting said edge against a stop formed in an outline having projections and indentations indiscriminately to position said outline on the element in relation to said outline of said stop, and pressing said element toproduce thereon marks in indiscriminate relation to said edge thereof.

34. In combination with a die formed for making depressions in the face of an element, a stop against Which an edge of the element may be set to position the element in relation to the die, the face of said stop against which said edge of the element is set being formed in an outline having indentations and projections.

35. Process of producing a plurality of dissimilar covering elements which comprises forming an edge on each element with an outline having projections and indentations, setting said edges of said elements in succession against a stop formed in an outline having projections and indentations with successive elements against different portions of said outline of said stop, and pressing the faces of the elements to produce depressions in said faces which are different in the different elements.

STEWART W. CHAFFEE.

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