US1625888A

US1625888A - Roofing element and method of making the same

Info

Publication number: US1625888A
Application number: US657489A
Authority: US
Inventors: Julius H Gillis
Original assignee: ANACONDA SALES CO
Current assignee: ANACONDA SALES CO
Priority date: 1923-08-15
Filing date: 1923-08-15
Publication date: 1927-04-26
Anticipated expiration: 1944-04-26

Description

1,625,888 Ap 26 1927' J. H. GlLLlS ROOFING ELEMENT AND METHOD OF MAKING THE SAME Filed Aug. 15 1923 NVENTOR J M8 ATTORNEYS I such Patented Apr. 26, 1927.

UNITED. STATES PATENT OFFICE.

JULIUS H. GILLIS, OF ELIZABETH, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 ANACONDA SALES COMPANY, A CORPORATION OF DELAWARE.

ROOFING ELEMENT AND METHOD OF MAKING THE SAME.

Application filed August 15, 1928. Serial No. 857,488.

This invention relates to roofing elements and processes for making. the same, and has to do primarily with roofing elements in the form of boards, strips, tiles, single or multiple shingles, and the like. These elements are of the composite type and consist of a base formed of various materials wellknown in the art under the general name of roofing compositions, and a protective metallic layer or coating applied to the base to form a weather surface therefor.

Composition roofings are in wide use at the present time, and serve to replace roofing materials hitherto used, such, for instance. as wooden shingles, slate, etc. These composition roofings are formed of paper, felt, burlap, or similar materials, impregnated with water-proofing materials as bituminous substances, magnesite compositions, and various other non-hygroscop c, heat insulating materials held together with a suitable binder. Such composition roofing material is used in a variety of forms, as, for instance, strips,

- s ngle or multiple shingles, tiles, etc. The

multiple shingles consist of a strip of roofing of appropriate dimensions having an indented edge so formed that when these elements are laid in courses in the usual manner the indented edge is exposed so as to give the usual appearance of a shingle roof.

Composition roofings of the type above generally referred to have numerous advantages, due to their comparatively low cost,

' easy method of application,and heat insulating quantities. However, when such elements are laid in place on the roof in overlapping courses the exposed portion is likely to warp or curl, and after periods of use the composition deteriorates due to the volatilization of the oils used in their manufacture.

' Also such composition materials are not al of metal has also been in common use combine the advantages of the two types previously referred to, is shown and described in the Patent No. 1,449,058, granted March 20, 1923, to Thomas. Robinson. This element consists of a composition base of various forms, prepared by methods which are well known. On that surface of the element which is to be exposed to the weather, there is applied athin coating of a non-corrodible metal, such, for instance, as cop er or zinc. This metallic coating is limitec to the Weather surface of the element and it serves to stiffen the base to prevent warping and curling, to protect the relatively soft base materials, and to prevent deterioration caused by volatilization of the base oils. By using a thin layer of metal and by limiting this layer tothe Weather surface of the element, the cost of the new type of roofing is but little greater than that of the unprotected base and such elements may be laid as easily as ordinary composition roofings and without that degree of care which is necessary in the case of metallic roofings to revent leaks. In the patent above referrec to the metal coatmg is applied directly to the surface of the base in various ways, as for instance, by electrodeposition. In the co-pending application of Thomas Robinson, Ser. No. 618,246, filed February 10, 1923, there is shown and described a somewhat similar element which is given an attractive appearance by the application of a layer of grandular material such as crushed slate or crushed petroleum coke pressed into the surface of the base before the metallic layer is applied. Also in the co-pending application of Thomas Robinson, Ser. No. 652.563,

filed July 19, 1923, there is shown and described a process for making elements which consist of a base and a preformed metallic layer which is applied thereto by pressure. In this particular process the base is of ordinary composition and may have either a lain or granular surface to which a pre ormed metallic layer or coating, cut to the approprate size and shape, is applied by the application of pressure sufiicient to cause the metal to conform to the irregularities of the base and adhere thereto.

The present invention is intended to improve the quality of the roofing elements made by either the electrolytic or pressure processes, above referred to, and is intended further to provide a process by which there is secured a stronger adherence between the metallic coating and the base. It is adapted especially for use with electrolytic processes for applying the coating for in such processes it will be clear that it is necessary to give the base a coating of electrical conducting material before the metal is applied thereto. The conducting material which is ordinarily used for this process is powdered graphite, which is held in place by the use of a suitable adhesion. In preparing the elements for the deposition of the metal their weather surfaces are sprayed or otherwise treated with an adhesive which may take the form of a saturated solution of asphalt in carbon tetrachloride. A layer of powdered graphite is then dusted or brushed thereover and when the adhesive dries the raphite is firmly held in place. This conducting coating is necessary for the electrolytic rocesses in which the metal is deposite over the coating in such a wa as to conform to the irregularities of the use so that a good binding effect is produced. However, it sometimes happens, due to carelessness on the part of the workman, that the conducting material is applied unevenly or in a much thicker layer than is necessary for carrying on the deposition, and if too thick a layer of graphite, which has lubricating qualities, is applied to the base lying between it and the metallic layer extreme changes in temperature causing expansion and contraction of the metal, may result in loosening this layer from the base.

The object of the present invention may be restated then, as the provision of a process by means of which the metallic layer is bound firmly directly to the base even though there is an intervening coating of conducting material and this process improves the quality of the roofing even in those cases where the layer is applied by pressure and no conducting material intervenes between the metal and the base. In carrying out the process, I take advantage of the fact that the base contains a plastic substance which softens and expands upon heating and I heat the metallic coating after the latter has been a lied to the base either by pressure or depositlon, confining this heat to the metal in such a way that only a thin stratum of the base immediately underlying the coating is heated by conduction. This application of heat causes the plastic material on and in the base to soften and swell and during this heating I apply pressure to the metallic layer so as to cause the softened plastic material to wet the layer over all its surface in contact with the base. The heat is applied and regulated in such a way that the base itself is not heated throughout its thickness and I prefer to apply the.

as to give the desired effect without soltening the base so that the element cannot be readily handled.

In order to secure a good bond between the base and the layer I prefer to use a base which contains asphalt as an ingredient although other similar materials used for binders in the past are also satisfactory. The new process, however, is applicable in connection with any ty e of base, whether or not it is impregnatecFwith asphaltic material, although in'the latter case it is preferable to use an adhesive containing asphalt for binding the conducting coating to the base. If no conducting coating 15 to be used, as in the case of preformed metallic layers applied by pressure, then it is preferable to apply a thin film of as halt or similar material to the base before t a metal is pressed in place thereon.

In taking advantage of the plastic material on and in the base for causing the layer to adhere thereto, there are several essentials which must be borne in mind in connection with the heating step. I have found that the bond is the stronger, the hotter the layer is made, but in applyin this heat it should be limited to the layer because if the heat enters the base to any reat extent, it is likely to cause volatilization of the oils and to soften the base and render it flexible so that the elements after the heating cannot be readily handled but must be stored and allowed to cool in such a way that they will not warp. Again it is necezsary that the heat should beuniform throughout the metallic layer, otherwise bulging of the la er is likely to occur with the result that w en the source of heat is removed the layer will not conform properly to the surface'of the element. It is also necessary that the heating should be carried on rapidly and that the layer should be raised to a temperature sufficient to soften the plastic material in the base only to a very slight depth. The longer the heat is a plied, the greater will be the layer of the ase which is softened, and while it is only necessary to heat the plastic material in a thin stratum of the base in order to secure a firm bond, slow-heating does not improve the quality of the bond but on the other hand causes the heat to be conducted into the base so that it is sof' tened. The application of pressure during the heating improves the quality of the bond but such heat and pressure cannot be carried on by any of the ordinary methods such as by passing the elements through steam or gas heated rolls because the heating so produced is too slow. Also it is not possible to carry on the heating by the application of flames directly on the metal, masmuch as such treatment results in the deposition of combustion products on the metal injuring its appearance and in some cases causing a. slight corrosion. Heating by flame also has the disadvantage that it is almost impossible to secure an even and uniform application of heat, and, as has previously' been explained, this results in bulging of the layer.

I have found, however, that application of heat with the desired rapidity under the proper regulation and without .theseveral other disadvantages of hot roll or flame heating, may be carried on by making use of the heating effect of the electric current. For this purpose I use presses or rolls provided with suitable contacts which cause a current of the desired intensity to flow through the metallic layer. This rapidly generates heat which is localized and confined in the layer and which does not spread to any appreciable extent into the base. By properly regulating the current the heating operation may be carried on economically and with great ra idity, and the elements which have been su jected to the application of heat and pressure may be easily supported in a way which prevents warping or curling of the base or bulging of the layer. Also by generating heat in the layer itself there is no possibility of the layer bulging or expanding away from the base.

Various mechanical devices may be used for carrying on the present process, but in the accompanying drawings I have illustrated various forms of mechanism which are satisfactory for such purposes. In these drawings,

Fig. 1 is a cross-sectional view of a smooth surface element showing the metallic layer applied thereto,

Fig. 2 is a View similar to Fig. 1, but showing the metal applied over the granular surface,

Fig. 3 is a plan view of a multiple shingle element showing the outline of the coating and location of the contacts,

Fig. 4 is a view similar to Fig. 3, showing the modifications necessary in connection with a single shingle element,

Fig. 5 is a view similar to Fig. 3 but showing the contacts in modified form,

Fig. 6 is a diagrammatic view in side elevation of a pressure device provided with contacts,

Fig. 7 is a plan view of a flashing strip having a metallic coating,

Fig. 8 is a view in side elevation of a modified form of device for treating such strips,

Fig. 9 is a cross-sectional view of a detail of the pressure rolls used,

Fig. 10 is a phantom view of one of the rolls showing the current paths.

Referring now to the drawings, the roofing element is seen to consist of a base 11, provided with a metallic coating 12, extending over the weather surface of the base and applied in such a way as to conform to the rregularities thereof. In the element shown in Fig. 1. the base is illustrated as having irregularities which are shown somewhatenlarged for purposes of illustration. It

will be understood that the presence of these to be applied. In Fig. 2 the base is shown to be provided with a granular layer 13, disposed over the surface thereof. This granular layer, as has previously been explained, may consist of crushed slate or crushed coke which has been pressed into the surface of the base while the latter is still soft. The element illustrated in Fig. 2- has a metallic layer 12, applied over these granules in such a way as to enter the interstices between'the granules and so conform to the irregular surface. In Fig. 3 the element 14 is of the multiple type a d one edge is provided with cut-outs ll which serve to define three separate shingles 16 These cut-outs are formed so that when the multiple element is laid in place only the projecting portions defined by the cut-outs are exposed, and a roof formed of multiple elementshas the usual appearance of an ordinary shingle roof. In this form of element each of the shingles defined thereon is provided with a metallic layer 16, terminating at the rear end in a neck 17 which is extended so as to underlie thev cut-out of the shingle of the overlying course. With this arrangement it will be seen that all the exposed portions of the. shingle are covered with metal so that to all intents and purposes the roofing may be considered to be a continuous metallic roofing. The ele ment illustrated in Fig. 4 is a single shingle of the usual outline having a coating 18 which terminates in a. triangular portion 19 which serves to underlie the space be tween adjacent elements of the overlying course. As these shingle elements are usually laid by hand the portion which underlies the space between the elements of the next course above is made somewhat greater than the neck 17 so as to allow for carelessness of the workmen in applying the shingles.

The new process may be practiced with out regard to the particular shape and size Ill) of the roofingelements to be treated, but slight modifications are necessar in the construction of the resses'or rol s as the case may be, and a so in the location of the contact members, according to the outline of the elements and the sha e and size of the metallic layer thereon. or convenience the elements have been shown in a form which is widely used at present, and the necessary contacts and electricalconnectlons are designed for use with such elements,

but it will be understood that the general:

principles here set forth are applicable regardless of the particular outline which the elements have.

Referring now to Fig. 6, the ress which I make use of has a bed 20, t e working face of which is preferably provided with a layer 21 of yielding material, such as rubber. Mounted above the bed is a movable plunger 22, which may be mounted to 'move in a standard in accordancewith the usual press construction. The face of this plunger is provided with a yielding cushion surface 23 which ma be made of rubber suitably treated to withstand the temperatures which are to be em loyed. This rubber cushion will be preferably secured 'in place in the plunger in any convenient way, so that it may be readily removed and replaced when occasion demands. Secured in the face of the plunger and insulated from the body thereof, are spaced contacts, these contacts lying flush with the surface of the cushion so that when the plunger is depressed against an element laid on the bed the contacts will strike the face of the element while ressure is exerted through the cushion to iold the metallic layer of the element firmly against its base. It will be understood that the shape and size of the plunger will depend upon the shape and sizeof the element which is to be treated, and the spacing of the contacts in the face of the plunger will also depend on the form of the metallic layer which has been applied to the element base. In Fig. 3 there are shown contacts suitable for a multiple element which consists of three shingles united along their rear edges. Located in the face of the plunger are spaced contact-s 25 which will engage the metallic layer of the element along its rear edge where the neck portion joins the body of the layer.

H Contacts 26 serve to engage the front edge of each layer and the curved contacts 27 are spaced so that when the plunger is depressed these contacts will engage the end of the neck portions. The contact 25, as is illustrated in the right of Fig. 3, is connected to one terminal of a source of power and the current accordingly enters the contact 25 and spreads in both directions through the metallic coating bein taken off through

contacts

26 and 27. hese contacts are then joined by a conductor 28 which lies within the face of the plunger and the conductor 28 is in turn connected to the contact 25 for the next metallic layer. The current spreads through this layer as before, passes out through

contacts

26 and 27, and enters the central contact 25, being finall taken off by means of a conductor 29 which connects the

contacts

26 and 27 for'the layer at the left in Fig. 3. This conductor is then connected to the other side of the line. "It will be clear that when the contacts are out of engagement with the layers of the element no current will flow but immediately upon depression of the plunger into contact with the element current will flow through the metallic layers, as has been explained.

The contacts illustrated in Fig. 4 have been designed to take care of the'particular form of metallic layer used in a single shingle. There is'a central contact bar 30 across the layer at the base of the triangular portion, an annular contact 31 which engages the layer at the apex and another contact 32 which engages the front edge of the layer. The current aths are similar to those previously described, the current entering through the central contact and spreading through the layer, to be taken off through the

contacts

31 and 32. In Fig. 5 there is shown a somewhat modified layout for the contacts which shows the use of conductors within the face of the plun er. In this arrangement there is provide a contact 33 which engages'one metallic layer along the top ed e and along the side of the mp1; portion. nother contact 34 extends along the front edge of one la er, then rearwar 1y to overlie the edges 0 adjacent layers, then along the edge of the second layer, and up and around the neck portion, as before. Contacts similar to 34: are used in any number desired, depending on the number of shingles in the element, and the current is then removed through a contact 35 which extends alon the front edge of one layer and rearwar 1y along its side. In this arrangementcurrent will enter contact 33 and travel through the metallic layer to the contact 34, passing through the contact to the next layer, thence through the layer to the next contact 34, and thence out through contact 35. The contacts are so designed that current will flow through all portions of the metal layer, heating it evenly and uniformly.

In Fig. 7 there is illustrated a form of roofing material useful for flashing stri s. This consists of a long strip of base material having a facing of metal and for ap lying heat and pressure to such a stri 1 have found it convenient to make use 0 pressure rolls provided with electrodes on the surface thereof. Such an arrangement is illustrated III pair of

rolls

36 and 37.

face of the roll. These electrodes may be connected to a suitable source of power by means of brushes or other contact arrangements and are designed so that the current enters one contact 39 of Fig. 10, and passes out the other 40. The current passing be\ tween the electrodes will accordingly travel through the metallic layer on the strip and in its passage will spread, through paths as illustrated at 41 in Fig. 10. The strip 42 is shown to enter the pressure rolls from the left in Fig. 8, passing through contact rolls 36, 37 and then passing through a series of rubber pressure rolls 43, which exert regulated pressure on the strip. The current may be so selected that the heating will be carried on rapidly and the strip is moved with a steady uniform movement through the rolls. If it is desired to increase the rate of heating itis possible to make use of a series of contact rolls 36, 37, as shown at the, right in Fig. 8, the strip moving from these rolls being later subjected to pressure between rollers similar to those illustrated at 43. In its passage through the rolls the metallic layer is heated by the current travelling between the electrodes and pressure is applied not only by the electrode rolls but also by the succeeding rubber pressure rolls, so that when the strip emerges from the apparatus the binding of the metal to the base is complete. It is necessary that the pressure rollers 43 should be spaced and aligned in such a way as to maintain the strip in its straight condition withoutsagging or bending until theflp'lastic material which has been caused to-wet the metal during the heating has set, as ot erwise the metal might pull away from the b so and the desired adherence be lost.

I have found that a satisfactory bond is secured by heating the copper to approximately 350 F., although the degree of heat will naturally de end on the character, of the plastic material which serves to produce the bond. Theparticular degree of heat above referred to has been found satisfactory in the case of an element to which the metallic layer has been applied by electro-deposition' over a thin film of graphite held in place by an adhesive containing asphalt. The pressure required in the above example is ap-- proximately 25 pounds per square inch and I have also found that a current of approximately 150 amperes per inch of width of the coating is about the mostsatisfactory intensity. The voltage required to produce such a current in this particular type of element is approximately one half 9. volt for contacts whlch are five inches :1 )art, and the applicat1on of such a current for a period oftwenty seconds produces the desired heating elfect.

ril have found that-the application of heat as above described causes the plastic material of the base to expand and swell with a slight bubbling effect which causes this soft-' ing layer with the result that this layer is absorbed' in the base and accordingly does not intervene between the surfaceof the base and the metal. This is particularly true where the conducting layer is graphite which has been caused to adhere to the base by means of an adhesive containingasphalt.

The process above described results in a thorough binding of the metal to the base throughout the surface of the metal and is a plicable whether the metal has been appiied by electro-deposition or by pressure. In the first case, however, it has the advantage of causing theconducting material to be absorbed into the base and this is of peculiar advantage where graphite is used owing to the lubricating qualities of the graphite. The process, however, is of equal ap lication where the performed layer is applied by pressure and is also capable of ap lication to roofing elements made in accorc ance with the process disclosed in the co-pending application of Thomas Robinson, Ser. No. 606,339, filed Dec. 11, 1922, wherein the metal is applied in the form of a fine powder bound to the base by a suitable adhesive.

The generation of the heat in the metallic layer not only serves to confine and localize the heating effect so that the base is not.

rendered flexible, but the element may be readily handled at the completion of the process, since the heat does not extend into the base to any appreciable extent. I have also found that this a plication of localized heat has another incidental advantage inasmuch as the heating is carried on under those conditions which are best for annealing the metal layer. This results in improving the quality of the metal, as well as producing a more perfect bond.

The contacts which are used for causing the current to flow through the metal may be of copper, iron, or nichrome, and will last indefinitely. Also the cushion which is applied to the face of the plunger and to the rollers may be made of rubber of such characteristics that it will readily withstand the degree of heat required and since this heat is of comparatively low temperature and is applied for a comparatively short length of time, the cushions will last for an indefinite period. It will accordingly be seen that the process is relatively inexpenoperation.

sive to carry on and the bond between the metal and the base is not produced by added materials but by materials which are present in the base or necessarily applied thereto in connection with the application of the conducting material.

It will be understood that the moving plunger in the press is preferably powerdriven, and is arranged so that the pressure to be exerted by it may be regulated. The simplest form of press will be provided with a single lunger of such size as to act on a single. e ement at a time. Ordinarily a plunger arranged to act on a four-shingled unit will be the maximum size used, although multiple shingle units may be treated in a single unit press, pressure being exerted successively on each of the shingle coatings. Ordinarily it is most convenient to arrange the presses in airs so that one workman can feed roofing e ements to them in alternation, and the time required for the application of heat is just about suflicient for placing anew element in the press and starting the heating From the presses the elements are conveyed to storage-warehouses or shipping platforms and since the metal layer is comparatively thin it will radiate heat with such rapidity that the elements may be handled by the workman as soon as they are removed from the press. Also the elements are not appreciably softened during the the heating operation, and it is not necessary to permit them to cool off before they are handled.

I claim:

1. A method of making roofing elements, which comprises preparing a base containin a plastic substance, allowing the plastic su stance to assume a non-adhesive condition, applying a metallic layer to the surface of the base, and simultaneously heating the metal and pressing it against the base, the heating of the metal being carried on to an extent sufiicient to soften the plastic substance and render it adhesive.

2. A method of manufacturing roofing elements, which comprises preparing a base containing a plastic substance and having an irregular surface, allowing the plastic substance to assume a non-adhesive condition, applying a metallic layer over the irregular surface of the base in such manner as to conform to the irregularities thereof, and simultaneously heating the metal and pressing it against the base, the heating of the metal being carried on to an extent suf-' ficient to soften the plastic substance so that it wets and adheres to the metal.

3. The method of manufacturing roofing elements, which comprises preparing a base containing a plastic substance, allowing the plastic substance to assume a nonadhesive condition, applying a metallic layer to the surface of the base, pressing the neaaaea layer of metal against the base, and, while the metal and base are so held, generating heat in the layer sufiicient to cause the lastic substance in the base to soften an adhere to the under surface of the metal.

4. The method of manufacturing roofing elements, which comprises preparing a base containin a plastic substance, allowing the plastic su stance to assume a non-adhesive condition, appl ing a metallic layer to the surface of the base, and passing an electric current through the layer to heat the latter to an extent sufiicient to soften the plastic substance to cause it to wet the layer and adhere to it.

5. The method of manufacturing roofing elements, which comprises preparing a base containing a plastic substance, allowing the plastic substance to assume a non-adhesive condition, applying a metallic layer to the surface of the base, pressing the base and layer into intimate contact, and, while the base and layer are so held, causing an electric current to flow throu h the layer to raise the temperature of the latter to an extent suflicient to soften the plastic substance and render it adhesive.

6. The method of manufacturing roofing elements, which comprises preparing a base containin a plastic substance, allowing the plastic su stance to assume a non-adhesive (ondition, applying a conductive material to the surface of the base, electrodepositing a metallic layer over the conducting coating, holding the layer and base in intimate contact, and heating the layer to an extent sufficient to soften the plastic substance and render it adhesive.

7. The method of manufacturing roofing elements, which comprises preparing a base containing a plastic substance, electrodepositing a metallic layer on the surface of the base, pressing the base and layer into intimate contact, and, during the pressing operation, generating heat in the metallic layer to raise its tem rature sufficiently to soften the wet and ad ere to the metal.

8. The method of manufacturing roofing elements, which comprises coating a base with a film of asphalt, allowing the asphalt to cool and harden, applying a metallic layer over the asphalt coating, pressing the base and layer into intimate contact, and, during this 0 eration, generating heat in the layer su cient to soften the as halt coating to cause the latter to wet and a here to the under surface of the metal.

9. The method of manufacturing roofing elements, which comprises coating a base with an asphaltic film, allowing the film to cool and harden, applying a conducting coating over the film, electrodepositing a metal layer over the conducting coating. and generating heat in the layer to raise Ill) lastic su stance to cause it to its temperature sufficiently to cause it to soften the asphaltic film so that the latter adheres to the metal.

10. The method of manufacturing roofing 7 elements, which comprisespreparing a base containing a plastic substance, allowing the plastic substance to assume a non-adhesive condition, applying a conducting coating to the base, electrodepositing a metallic layer over the coating, and heating the layer to cause it to soften the plastic material to an extent sufficient to cause the layer to absorb the conducting coating and wet and adhere to the layer.

11. The method of manufacturing roofing elements, which comprises preparing a base containin a plastic substance, allowing the plastic su stance to assume a non-adhesive condition, applying a metallic layer to the surface of the base, and progressivel uniting the base and layer by generating eat in the layer while it is in position on the base, the heating being carried on to an extent sufficient to soften the plastic substance and render it adhesive.

12. The method of manufacturing roofing elements, which comprises preparing a base containing a plastic substance, allowing the plastic substance to assume a non-adhesive condition, applying a metallic layer to the surface of the base, and uniting the base and layer by progressively ressing the base and layer into contact and simultaneously generating heat in the metal to an extent sufficient to soften the plastic substance and render it adhesive.

13. The method of manufacturing roofing elements, which comprises preparing a base containing a plastic substance, allowing the plastic substance to assume a non-adhesive condition, applying a metallic layer to the surface of the base, and uniting the base and layer by progressively pressing the layer into contact with the base and causing an electric current to flow through the layer along a path moving throughout the length of the layer, the current raising the temperature of the metal to an extent sufiicient to cause it to soften the plastic material and render it adhesive.

14. The method of manufacturing roofing elements, which comprises preparing a base containing a plastic substance, allowing the plastic substance to assume a non-adhesive condition, applying a metallic layer to the base, and passing the base and layer through pressure rolls and causing an electric current to flow through the layer along the line at which the maximum pressure is exerted, the current raising the temperature of the metal to an extent suflicient to soften the plastic material and render it adhesive.

15. A roofing element which comprises a base coated with a plastic substance, a conducting coating over the plastic coating, and an electrodeposited metallic la er over the conducting coating and boun base in part by the plastic substance which adheres to the under surface of the metal.

16. A roofing element which comprises a base coated with an asphaltic compound, a coating of graphite on the surface of the base, and an electrodeposited metallic layer to the over the graphite, the metallic layer in part adhering to the graphite and in part being held to the base by means of the asphaltic compound which contacts with the under surface of the metal and adheres thereto.-

In testimony whereof I aflix my si ature.

JULIUS H. GI LIS.