US1613515A - Method of producing chromophotographs on paper and chromodiapositives - Google Patents

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1,613,515 1927' F. JANZEN METHOD OF PRODUCING CHROMOPHOTOGRAPHfi ON PAPER AND CHROMODIAPOSITIVES Filed March 14. 1923 Patented Jan. 4, 1927.

UNITED STATES PATENT OFFICE.

FRANZ JANZEN, or: BERLIN-TEMPELHOF, GERMANY, ,ASSIGNOR 'ro WILLY VOIBACH, OF BERLIN, GERMANY.

mn'rnzon or PRODUCING cnnomornoroenarns ON PAPER AND ennomonmrosr- 'rrvns.

Application filed March 14, 1923, Serial No. 625,185, and in Germany March 16, 1922.

This invention has reference to unicolored and multicolored chromophotographs on paper and to diapositives, and it is particu larly intended to so improve the manufacture thereof "that the manufacture of the prints is facilitated and it is also an object of my invention to devise novelv means of producing the color sensitive coating and. of transferring the picture to the printing plate. Other objects and advantages of my invention will appear as the specification proceeds.

,Broadly speaking my invention is based on the so-called suction or imbibing method, according to which a suitably prepared copy from the negative is colored with aniline dyes, and is then covered with gelatine paper so as to be in intimate contact therewith. After some time the color from the copy has been transferred to the paper with all the delicate shades and tints in the lighted and shaded portions. Upon these principles is based for example the so-called pinatype process owned by the Hochet Dye-Works of Meister-Lucius & Briining. In accordance with the process referred to an ordinary black-and-white diapositive is made from the negative, and from the diapositive a print is made upon a glass plate coated with gelatine which has been sensitized by means of chromates. The printing plate thus obtained is now colored with aniline dyes which are adapted to tint unhardened gelatine very strongly, while hardenedgelatine is only slightly tinted or not colored at all.

I The hues produced in this manner are, moreover, not only proof against washing, but they also fail to be blurred and to merge into the gelatineso that sharp pictures are produced. This previous method presents the inconvenience that it requires-a diapositive and then a printing plate to be made therefrom. 'Nor is it possible to obtain clean pictures, inasmuch as the pictures are always somewhat smudged with colors, no matter how much the plates have been hardened.

Upon being used repeatedly the printing plates become gradually darker, so that it soonbecomes impossible to produce exactly registering partial pictures. Entirely new printing plates then have to be made.

"-All these drawbacks and inconveniences are overcome in my invention which otherwise makes use of dyes and pigments having the same properties as in the previous processes referred to. In the new process, howm'er. the diapositive copied from the negative is utilized directly as a printing plate. In View thereof a film is coated with a layer of a suitable colloid containing insoluble substances in the finest state of distribution scarcely colored by the dyes and pigments hereinbefore mentioned, inasmuch as the colors are capable of permeating into the gelatine which has become porous, so to speak, by the addition of the inert substances. mixed colors will fail to produce the desired results. On the other hand, in contact with gelatinized paper the colors are extracted and are sharply and unobjectionably transferredto the paper.

In the accompanying drawing, which is a distorted diagrammatic section, the transparent supportis indicated at 1, the bichromated colloid coating at 2, and the insoluble granules which are distributed throughout said coating at 3.

The foils produced are rendered sensitive by the addition of bichromates, and are copied from the back sides. They are then developed like a igment picture in warm water without being transferred, and are then tinted. Such development in warm water effects the washing out of the finely divided substances, since the microscopical substance does not dissolve in the colloidal layer, nor are they finely embedded therein and their washing out from the colloidal layer leaves the latter in a porous condition as above stated. Inasmuchas the unexposed portions are washed 0 t in accordance with the degree of hardening, they always remain clear and clean. The printing foils obtained do not become darker even upon being re- It has been ascertained .that unpeatedly used, so that exact registration of the partial pictures in the three-color-printing process is ensured.

As far as I am aware inert or indiiferent substances, such as asphaltum, mineral coal have been added to gelatine only for the purpose of producing in pigment pictures a certain kind of grained back ground similar to the so-called helio-engraving.

The invention has been described herein only in its broad aspects, and it is obvious that it may be modified to suit existing conditions and the convenience of the operator, and without being restricted to any particular form of execution, except as set forth in the claims hereunto appended.

I claim 1. The method of producing photographic pictures in natural colors, consisting in producing printing film's by copying from the back surface of negatives exposed through three color filtersred-bluegreen; the )rinting films each consisting of a colloidal iayer applied to a transparent base and thoroughly impregnated with extremely finely divided substances insoluble in the colloidal layer, washing out such substances to render the film porous, saturating said porous film with a different color solutlon, and successively pressing such color saturated films upon photographic paper which has been rendered durable against light to transfer the colors to the paper.

2. The method of producing photographic pictures in natural colors consisting in pro-.

ducing printing films by copying from the back surface ofnegatives exposed through three color filtersredbluegreen; the printing films consisting of a colloidal layer applied to a transparent base and thoroughly impregnated with extremely finely divided substances, such as chalk, soot of volatile signature.

FRANZ J ANZEN.

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