US1901049A - Process for the production of genuine watermark papers without using relief molds - Google Patents

Description

' screens.

Patented Mar. 14, I 1933 PATENT: orrrir Lfithttt FRIEDRICH VON HEINRICH, BUDAPEST, HUNGJQRY, ASSIGNOR OF ONE-HALF no NATIONAL BANK OF HUNGARY, 0F BUDAPEST, HUNGARY, A CORPORATION OF HUNGARY rnocnss non THE rnonuo'rron or GENUINE WATERMARK reruns wrrnour name names norms 1T0 Drawing. Application filed October 15, 1931, Serial No. 569,118, and in Austria October 20, 1930.

Watermark papers have hitherto been made in most cases on sieves, bearing the watermark embossed in relief, 'the parts showing up dark in the paper forming the recesses, and the light parts in relief. For this purpose a wax relief was molded in accordance withthe desired design, and representing the tone values of the latter as thinner or thicker portions when viewed by transmitted light. From this wax original, a negative electro was made, and from this latter a metal positive, a fine bronze gauze between the two being then submitted to such pressure as to transfer the projections and recesses of the wax original to said gauze. This fine sieve was'then used as a paper forming mold.

Genuine watermarks were also produced by means of metal wire ornaments, script and the like soldered or welded to the sieves or In this case, the watermarks are produced'by the fact that at the places'where the wire ornaments and the likeare secured there is a decrease in water permeability and the relief portions of the wire cause a reduced deposit of the paper material. If the water permeability of relatively large areas of the screen is destroyed by the presence of these ornaments, etc., no deposit of paper material will occur at these places and holes will form in the paper web at the places Where there was no deposit of paper material. If a paper web of this kind, i. e., one in which where paper actually formed the web is of uniform thickness and no watermark in the true sense of the word occurs, is placed on a second coherent web, the result is :a patterned paper .when viewed by transmitted light. In the production of multi-colored watermarks'by the method just described, the first 'web' is couched on a second, coherent,

web of a different 'color. It has also beenproposed to form watermarks in paper by means of a screen in which difierences in wat-er permeability thereof are produced by weaving the screen irregularly or by weaving thicker wires or patternsinto the same on Jacquard looms.

According to the new process'forming the.

subject of the invention, for the production of gradations or half tones in the formation of genuine watermarks. I start with a photographic reproduction of the design of the intended watermark, and efiect gradations in water permeability of the surface on which. the paper is formed correspondin to the light tone values of the photographic reproduction. This rocedure provides an entirely novel met 0d of producing directly from a photographic half tone picture, watermarked papers which faithfully reproduce all tone values and fine gradations of the photographic original. To this end it is essential, according to the present invention, to'decompose or break up the photographic half tone picture by means of a line screen, so that the light tone values of the half tone picture are represented by the relation between the covered and uncovered areas in the decomposed picture. If a paper forming surface be produced so that, corresponding to the icture decomposed by'the screen, the covere areas are, say, the water permeable places and the uncovered areas are water impermeable, it will be apparent that the photographic half tone serves for reproducing the identical picture in the watermarked paper.

A great variety of forms of procedure may be followed in using a half tone picture to produce areas of difiering water permeability in the paper forming surface. Une

vas metal, it is first necessary to efiect the decomposition by means of the screen in such manner that the uncovered places of the decomposed picture will be united as in a grid. lln some cases, it may be necessary to use a negative of the decomposed plate to achieve the desired connection of the surfacest "fo Elli tit)

' tun obtain the grid-like connection or interconnection of surfaces, the usual method of decomposing or breaking up half tone pictures may be employed. The resulting negatives, capable of being etched, may be transferred by any well known method to thin metal plates or sheets which may be etched through where not covered with resist.

Such metal plates 'or sheets, which may also properly be termed molds, may likewise be produced by applying to a metal plate by any suitable procedure (ofl'set printing, copying, etc.) electrically insulating areas corresponding to the shape of the screen decomposed areas. If a separating layer has been applied to the virgin parts of the metal plate and the latter be used as a cathode in a galvanic bath, the resulting precipitate may be stripped from the plate as a mold with parts differing in water permeability the electrically insulated parts appearing as holes. It is also within the contemplation of my invention to start with an electrically nonconductive surface, make a negative of the previously used screen decomposition on, say, glass, and make the covered areas electrically conductive, these areas being covered in the galvanic bath with metal. In all cases, the resulting product is a metal plate with a coherent surface, in which larger or smaller holes, corresponding to the photographic original and its light tone values, are so distributed that the water permeability of the sheet at its different parts is proportional to the light tone values of the original at the respective parts.

In the production of paper forming surfaces it also, obviously, is possible to start with negatives representing various colors. If the resulting molds for the production of half tone watermarked paper have correspondingly colored substances applied thereto and the colored half tone watermarked paper so produced is couched on a coherent, compact, transparent base serving as a picture carrier, for example on paper, multicolored watermarks result which when seen by transmitted light disclose colored ictures of the character of polychrome prints.

It will, of course be understood that the surfaces for producing the paper may be cylindrical in form, as is now thecase with the present type of circular screen machines, and other modifications in the details of the invention, within the scope of the appended claims, may be made without departing from the spirit of the invention.

Having now particularly described and ascertained the nature of my said invention, and in what manner the same is to be per formed, ll declare that what ll claim is v 1. The herein described method of producing gradations or half tones in the watermarks of paper, comprising the making of a design to be used as a watermark, decomposing said reproduction by a line screen, and reproducing the said decomposed reproduction on a paper forming surface withthe water permeability of said surface at various places proportional to thelight tone values of the corresponding parts of the photographic reproduction, the Water permeable and water impermeable parts of said surfaces corresponding with the resist covered and uncovered parts of the screen decomposition of the half tone picture.

2. The herein described method of producing polychrome watermarks in paper, comprising making a multi-color half tone reproduction of a colored design to be used as a watermark, decomposing said reproduction by a line screen, reproducing the said decomposed reproduction on correspondingly colored paper pulp supported by a coherent web serving as a picture carrier, and couching said pulp on said web to form colored watermarks which when viewed by transmit ted light, correspond to the color and tone to photographic half tone reproduction of the