US1974334A - Process of coloring silver images - Google Patents

Description

Sept., i8, 1934.. R. KAUFHOLD 1,974,334

PROCESS OF-COLORING SILVER IMAGE-.S

Filed sept. 2e, 1932 INVENTOR.'

A TTORNEYS.

Pim@ Sept-.18. 1934 v l- 1,974,334

UNITED STATES. PATENT or-ElcE PROCESS F VCOLORING SILVER 'IMAGES Robert Kaufhold, Feldkirch, Austria, assigner to the rm'. Koh-I-Noor-Bleistiftfabrik L. & C. Hardtmuth, (Jeske Budejovice, Czechoslovakia Application September 26, i932, Serial No. 634,981

In German'ynugust 30, 1929 4A claims. (ol. 295-5) 'I'he present invention relates to a process of however, besideslight colors also black pigments coloring silver images and particularly to a process or dark colors are applied to the darker areas of of coloring photographic positives and negatives. the picture, the print is covered with an uncolored Hitherto silver images were colored with transgelatine solution. The print may now be dried, 1 5 parent colors or covering dyes. When these but it is also possible tocontinue the treatment 50 known coloring processes are used it is', however, with prints in damp state. 'Iheprintisthereupon not possible to reproduce the. light and dark bleached. Suitable bleaching agents are, for inshades correctly, since the grey silver particles stance, the solutions used by the preparation of willshine through the layer of colors, whereby imbromoiland ozobromium prints. Solutions of "'10 pure tones are produced. Moreover, when Workthis kind will penetrate all layers and convert the 65 ing after these known methods, it would be neces- .blackened silver of the original image into white sary, in order to obtain satisfactory results, to silver. Simultaneously the ozobromium content color the areas of different light values individof the bleaching agents will cause a hardening of ually and with utmost care. This coloring the pigment layers superimposed on the silver .15 method is, however, hardly practicable and usuimage in accordance with the image proper. The 70 ally, therefore, for instance the leaves of clumps product is thereupon washed with tepid water. of trees or bushes are simply painted green with- During the washing procedure such colored layout regard to the fact, that each single leaf comers as still remain soft will be separated from the prises a plurality of color shades. Therefore, picture. The picture is now treated with a soft even carefully painted photographic prints will brush and simultaneously the picture may be re- 75 never be a really artistic reproduction of nature. touched, if desired. Finally the product is flxed The object of the present invention is to proand washed in the usual Way. vide a simple and practical process for producing Instead of painting rthe picture with pencils colored pictures from photographic prints which or solutions of pulverulent pigments the dyeing v will give better results than the processes hitherto may be performed by means of colored or tinged, 80

known. regular or irregular crystals or circles, pencils According to the present invention, in carrying or carbons, bronze colors, short colored silk outl a process of the kind referred to` above, the threads and the like. coloring is performed by applying pigments to a The essential feature of the present process 3Q photographic negative or positive, coating the consists in the fact that the original image (the 85 pigments with a layer of colored or uncolored finished silver image) iS at first colored with colloid and bleaching and washing the picture. powdered or pencil colors as a single or multi- Through this treatment the surplus of pigments colored picture, upon which the colloid, for inand of gelatine is removed. Thereupon the white stance, gelatine and preferably a dark colored -35 silver image is xed out and the pic.ure is washed. gelatine, is poured 01' Spread.

' The product obtained is a pure colored picture. The prOCeSS iS ShOWIl dagrammatally in the When a photographic positive is to be colored accompanying drawing in which Figure 1 indithe process may be carried out in the following cates the silver image before bleaching; Fig. 2 manner: after bleaching and Fig. 3 the completely xed 40` The print is painted roughly withpowdered pigimage. 95 ments, pencil colors or other pigment solutions The following takes place: In the process of in which no couoid is present. Pigment solupouring or spreading, See Fig. 1, the dark liquid tions are not so-called genuine color solutions, as layer of gelatine moistens the dry powdered color for instance, anilin color substances diluted in lying underneath down to the bottom. There- 4'5 water, but insoluble color substances finely divided f01e, by the penetration 0f the gelatine into the 100 in benzine, turpentine oil, etc., which vclatilize dry red or other powdered Color, a red glue layer after application, leaving the dry powder color and above it a dark glue layer lies on the silver behind.v Hereby no regard is taken to light and imagedark tones or shades. Groups of houses are, for In addition to this is a special characteristic linstance, simply colored brown or yellow, woods 0f the PrOCeSSI The red layer of the powdered 105 and meadows green and the sky blue. The paintcolor forms, as it were, a screen for the dark ed print is coated with a layer of colloid, preferlayer of gelatine lying above it. It absorbs the ably of colored or uncolored gelatine. If the liquid gelatine, but n'ot, the gross coloring parprint is colored only with light pigments, it is ticles contained therein. Therefore, the tone of coated with a dark colored gelatine solution. If, the red glue layer remains pure. 1l(

But it is not always necessary to use a dark coloredfglue layer although in most cases such a dark Ycolored-glue layer is applied. nFor cer*-V tain purposes, another tone may be employed and even a completely plain or colorless layer of glue.

Contrary to other processes in which the initial silver image is brought into contact with the already colored layers of colloid, the present process is carried out in a separate manner i. e., at first the pigment is applied and then the layer of glufe, whereupon both layers are united.

This is the essential feature of the process. It is Vpresumed that, the further treatment is already known.

Thereupon follows the bleaching and tanning of the silver image and therewith the tanning of the colored layers of gelatine lying above it and the removal of the untanned parts in a bath of Warm water. There remains then a colored image of gelatine as shown in Figure 2. The delicate graduations are reproduced by light co1- ors, as in the example by red, the middle densities by red and a small amount of black, and the shadings by a higher amount of black but in which the red ground shines through.

In this way it isV possible to produce a multicolored image i. e., an image in which the colors appear as in nature. When, for instance in a landscape, the sky is to be reproduced in a blue color, the woods and meadows in a green color etc., water colors are Vnot suitable for this purpose. t is true, they already contain the necessary colloid, glue or albumin, but it is not possible to apply the colorsin a completely equal manner one with the other. carried out as inthe present process i. e., when at rst,the coloring is effected by means of pastel colors or with the pastel crayon and only when the colloid is added, as above described,

by pouring or spreading it on the layer of colors:Y

Lazur-colors are transparent colors. In Fig. 3 the completely fixed image is shown.

'I'his is only possible whenY When coloring by means of fatty pigments the process may be performed in a manner now to be described, whereby an engraving-like effect is obtained: YThe fatty pigments are applied to the picture in the form of dashes or dots, whereupon the silver layer between the dashes or dots is bleached and the layer of fattyl matter is removed by means cf benzene. The picture is thereupon treated in the manner described above.

1. A process of coloring silver images comprising the steps of painting the image with suitable pigments, coating it with a layer of colloid, then bleaching it so that the colloid layers on the image become hardened in accordance with the original image, washing away the soluble colloid and fixing out the bleached silver.

2. A process of coloring silver images-'comprising the ,steps Yoi painting the image with suitable pigments, coating it with a layer of colored colloid, then bleaching it so that the colloid layers on the image become hardened in accordance with the original image, washing away theY soluble colloid and fixing out the bleached silver. Y i

3. A process of coloring silver images comprising the steps of painting the image with suitable pigments, coating it with a layer of an uncolored colloid, then bleaching it'so that the colloid layers on the Vimage become hardened in accordance with the original image-washing away the soluble colloid and fixing out the bleached silver.

' 4. A process of coloring silver images comprising the steps of painting the image with a phrrality of layers of suitable pigments, coating it with a layer of-colloid, then bleaching it so thatVVA the colloid layers on the image become hardened in accordance with the original image, Washing" away VVthe soluble colloid and xing out the bleached silver. Y

' ROBERT KAUFHOLD.

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