US1926620A - Process of producing monochrome or multicolor gelatin relief photographs - Google Patents

Description

Patented Sept. 12, 1933 PATENT OFFICE" UNITED STATES PROCESS OF PRODUCING MONOGHRODIE OR MULTICOLOR GELATIN TOGRAPHS Hans lierzog, Bremen, Germany RELIEF PHO- No Drawing. ApplicatiomMay 15, 1930, Serial No. 452,817, and in Germany May 17, 1929 9 Claims. (cl. 95-2) This invention relates to the production of monochrome or multi-color gelatin relief photographs, particularly for the three color photographing. The relief formation of monochrome 5 and multi-color photographs by means of pigment foils sensitized in 'bichromate solution is known, and it has already been proposed; to develop sensitized emulsions by means of a tanning developer (pyrocatechin) either alone or mixed with a small percentage of sulphite and to harden the gelatin, whereupon the unhardened gelatin portions were washed. It has also been proposed to use a pyrocatechin developer for pigment photographs.

Compared herewith the, invention consists in applying to photographic emulsions (for instance halogen-silver-emulsions) soluble, non-diffusing colloidal and highly transparent dyes (substantive cotton dyes), in which the emulsions are colored, such emulsions serving then for the production of-monochrome or multi-color gelatin, relief ,photographs' in the multi-color-specially three color photography. the removable emulsions containing thenon-diffusing colloidal dyes being squeezed on paper after their tanning developmentproducing relief pictures, dried and pulled ofi.

The colloidal color photographs are quite clear, as the photograph, when being transferred onto paper do not diffuse. This is especially advantageous for the production of three color photographs, as these, when the individual photographs are made on emulsions capable to be transferred; require the prevention of diffusions of the colors at the transferring upon color emulsions which have already been properly mounted.

The invention consists further in that the in- ,dividual relief photographs, produced by tanning developing and colored with nondiffusing' 'colloidal dyes", are mounted successively on a support such as paper, celluloid or the like so that-the contours register and then pulled off their emulsion carriers, each emulsion being pressed on the support and dried, before the next following emulsion is pressed on, so that the finished multi-color photograph consists only of superposed transfer-- special manner of applyingthe developer and in a support.

. vat dyes.

the organic, waterl Further features of the invention consist in thethe method of transferring the photographs upon Several examples will be hereinafter described. To the sensitized photographic emulsions organic, water soluble, gelatin coloring, ,non-diffusing colloidal dyes are added, and these emulsions are then used for the production of .monochromeor multi-color gelatin relief photographs; The sensitized emulsions, coated upon a trans- 1 parent support, are, in known manner, exposed through the support. The dyes may be taken from the range, of substantive dyes, such as monoazo, disazo or tetiazo dyes, sulphuretted or Such azo dyes which color substantively may also be used. The following are some examples of suitable dyes: Erica, Alkali blue, Benzopurpurin, Dianil red, Dianil ruby, Congo red, Hessian purple, Thiazi yellow, Para yellow, Indigo red, Indigo blue. Blue and yellow may be combined to produce green, and red and yellow to produce orange.

For developing such gelatin relief photographs produced with colloidal dyes there is used a solution containing the tannin, pyrocatechin, and sodium sulphite, in which the ratio of sodium sulphite to pyrocatechin by weight is greater than one-half. The use of a pyrocatechindeveloper without sodium sulphite enables to produce washable relief photographs but, because of the accompanying oxidizing reaction the gelatin, adjacent to the silver, is hardened and made insoluble. The use of a substantial quantity of sodium sulphite prevents oxidation and consequent hardening of the gelatin, and thus provides for its removal with hot water. When, according to the invention, colloidal dyesare added to the photographic emulsion, it will be found, that the tanning developer without the sulphite is incapable of dissolving the gelatin-dye-complex even, in very hot water. Only developing solutions containing higher quantities of sulphite are capable of dissolving an excess of the gelatin dye.

According to the invention a halogen silver gelatin layer, to which colloidal dyes'are added, is developed with a pyrocatechin developer containing a quantity by weight of sodium sulphite,

' in excess ofone-half the weight of the pyrocateehin in solution. At the subsequent treatment of the developed photographs with hot water a perfect dissolving of the'excessive gelatin-dye mass is'obtained. I It is of advantage, that it is not necessary to use excessively heated water for the dissolving. no

-Thegreater'quantity of sulphite used in the developer produces pictures with sharp outlines and ensures a greater durability of the developed solution and a cleaned matrix free from brownish oxidation products. The mixed tones, specially undesirable in color photographs, are prevented thereby. The application of a high sulphite percentage in such tanning developers presents further the advantage that the developer'can be used repeatedly, which is not the case for developers free from sulphite.

According to the invention the coloring can be made weaker as desired, by subjecting the support bearing the gelatin-dye-complexes to a warm water bath for a sufilcient time to accomplish approximate or complete dissolution of the excess complexes. Thus a f: vorable ,mutual blending of the part photographs can be obtained. For multicolor photographs this blending is important. At the copying and developing of multicolor photographs it happens frequently, that an excess of certain colors occurs. Excess of color can be easily eliminated, according to the invention, by weakening. Longer washing for weakening, as is for instance usual for mordant dyes photographs, absorption photographsor the like, is impossible for colloidal dyes relief photographs. Y

The individual relief photographs, containing non-diffusing colloidal dyes, produced according to the invention as described above, after the exposure from the back, by means of pyrocatechin developer and subsequent washing with warm water, are then placed the one after the other upon paper, celluloid or the like so that the contours register, every individual relief photograph being pulled off its removable emulsion carrier onto the paper the blue photograph in moist state is placed so that the contours register, moistened and then dried. The emulsion carrier of the blue photograph is then pulled off. One proceeds then in a similar manner with the red photograph. Thus it is obtained, that the several relief photograph emulsions, which are colored with colloidal dyes, are superposed on the support without the emulsion carriers. The production of a three color photograph is thus obtained which is absolutely bound on the supp fi- It is advisable, to use feebly colored paper as support, the coloring of which is complementary to the color which has to be absorbed. A tan paper or a good blue paper can for instance be used, whereby the blue-yellow-or red tinginess can be regulated or suppressed.

Every individual relief photograph can be produced, according .to the invention, with the aid of a half tone screen, mutually displaced half tone screens being for instance used for the differently colored relief photographs. In this layers can be produced on transparent supports.

I claim:-

1. That process of color photography which consists in preparing .a set of films having transparent supports coated with a light sensitive emulsion layer on one side, dyeing each respective emulsion layer with a respective primary color with a substantive cotton dye corresponding to such color, printing each film through its support from the corresponding color selection negative, developing the printed films to form positives in a solution of pyrocatechin and sodium sulphite, fixing the developed positives, and arranging the fixed emulsion layers in superposed registering relation and stripped from their supports.

2. That process of color photography which consists in preparing a set of films having transparent supports coated with a light sensitive emulsion layer on one side, dyeing each respective emulsion layer with a respective primary color with a non-diifusing-colloidal transparent substantive cotton dye corresponding to "such color, printing each film through its support from the. corresponding color selection negative, developing the printed films to form positives in a solution of pyrocatechin and sodium sulphite, fixing the developed positives, and arranging the fixed emulsion layers in superposed registering relation and stripped from their supports.

3. That process of color photography which consists in preparing a set of films having translparent supports coated with a light sensitive emulsion layer on one side, dyeing each respective emulsion layer with a respective primary color with a substantive cotton dye corresponding to such color, printing each film through its support from the corresponding color selection negative, developing the printed films to form positives in a solution of pyrocatechin and sodium sulphite, fixing the developed positives, placing one of the fixed positives on a permanent support with the emulsion side in contact with the permanent support, stripping the transparent support from the placed emulsion, similarly treating the remaining fixed positives to cause them to lie in superposed relation and in registry.

4. That process of color photography which consists in preparing a set of films having transparent supports coated with a light sensitive emulsion layer on one side, dyeing each respective emulsion layer with a respective primary color with a non-diffusing colloidal transparent substantive cotton dye corresponding to such color, printing eachfilm through its support from the corresponding color selection negative, de-

veloping the printed films to form positives in a parent gelatinous supports coated with alight sensitive emulsion layer on one side, dyeing each respective emulsion layer with a respective primary color with a substantive cotton dye corresponding to such color, printing each film through its support from the corresponding color selection negative, developing the printed films to form positives in asolution of pyrocatechin and sodium sulphite, fixing the developed posi-.

tives, and arranging the fixed emulsion layers in superposed registering relation and stripped from their supports;

6. That process of color photography which consists in preparing a set of films having transparent gelatinous supports coated with a light sensitive emulsion layer on one side, dyeing each respective emulsion layer with a respective primary color with a non-diffusing colloidal transparent substantive cotton dye corresponding to such color, printing each film through its support from the corresponding color selection negative, developing the printed films to form positives in a solution of pyrocatechin and sodium sulphite, fixing the developed positives, and arranging the fixed emulsion layers in superposed registering relation and stripped from their supports.

'7. That process of color photography which consists in preparing a set of films having transparent gelatinous supports coated with a light sensitive emulsion layer on one side, dyeing each respective emulsion layer with a respective primary color with a substantive cotton dye corresponding to such color, printing each film through its support from the corresponding color selection negative, developing the printed films to form positives in a solution of pyrocatechin and sodium sulphite, fixing the developed positives, placing one of the fixed positives on a permanent support with the emulsion side in contact with .the permanent support, stripping the transparent support from the placed emulsion, similarly treating the remaining fixed positives to cause them to lie in superposed relation and in registry.

8. That process of color photography which consists in preparing a set of films having transparent gelatinous supports coated with a light sensitive emulsion layer on one side, dyeing each respective emulsion layer with a respective primary color with a non-diffusing colloidal transparent substantive cotton dye corresponding to such color, printing each'film through its support from the corresponding color selection negative, developing the printed films to form positives in a solution of pyrocatechin and sodium sulphite, fixing the developed positives, placing one of the fixed positives on a permanent support with the emulsion side in contact with the permanent support, stripping the transparent support from the placed emulsion, similarly treating the remaining fixed positives to cause them to lie in superposed relation and in registry.

9. That process of color' photography which consists in preparing a set of films having transparent supports coated with a light sensitive emulsion layer on one side, dyeing each respective emulsion layer with a respective primary color with a substantive cotton dye corresponding to such color, printing each film through its support from the corresponding color selection negative, developing the printed films to form positives in a solution of pyrocatechin and sodium sulphite with the sodium sulphite exceeding by weight one-half the pyrocatechin, fixing the developed positives, and arranging the fixed emulsion layers in superposed registering relation and stripped from their supports.

HANS HERZOG.