US2026899A - Process of retouching photographic films or plates - Google Patents

Description

Jan. 7, 1936. K. KIPP'HAN 2,025,899

PROCESS 0F' RETOUGHING PHOTOGRAPHIC `FILMS OR PLATES Filed Nov. 25, 1931 ln ven for Patented Jan. 7, 1936 UNITED STATES PATENT FFiCE PROCESS F RETOUCHING PHOTO- lGRAPHIC FILMS OR PLATES Apucation November 25, 1931, serial No. 577,397 In Germany November 26, 1930 f 6 Claims.

, My present invention relates to retouching of photographic materials. One of its objects is -to provide a colored or turbid layer which allows to eect brightening retouches. Further objects will be seen from the detailed specification following hereafter.

I have found that the light-sensitive photographic material is rendered fit .for receiving brightening retouches by imparting to the emulsion layer, or the support or a special intermediate or back layer a coloration or turbidity which is not affected by the photographic baths. The colored or turbid layer may moreover be dulled in known manner by addition of pigments so that also the hitherto known darkening retouches may be made. The material causing the coloration or turbidity must be insoluble in the usual photographic baths, and therefore the coloration or turbidity will still be present after development and fixing of the photographic material. The coloration or turbidity remain unaltered until a. brightenlng retouch is necessary. In this case the material causing the coloration or turbidity will wholly or partly beremoved by a treatment with a suitable liquid. So I may use, for instance, organic dyestuls, such as Benzolichtgelb R L (ci'. lFlerz-David Knstliche organische Farb-l stoffe 1926, page 168) or Guinea green 2 G (cf. Schulz Farbstoitabellen '7. Auflage (A) 762), or pigments such as ferrie hydroxide or calcium oxalate. In order to realize the retouches suitable solvents or bleaching solutions for these materials are used. In the case of Benzolichtgelb R L an acid hydrosulflte solution may be employed, in the case of Guinea green 2 G decoloration may be edected with a dilute solution of caustic alkalis whereas the action of dilute acid on the layer decolored in this manner reproduces the color. Ii' the layerenabling retouching con- 40 tains ferrie hydroxide brightening may be eifected with a solution of oxalic acid, and if the layer contains calciurn oxalate brightening may be eected with dilute hydrochloric acid. For producing a turbid layer i may use, for instance, resins; retong is eected by dissolving out these products with suitable solvents. If the layer contains mastic, alcohol is a suitable solvent.

ligive the following examples of carrying out my invention but without intending to limit it thereto.

Example 1,-50 grams oi freshly precipitated ferrie hydroxide are mixed in a collold mill with 1000 com. ci a gelatine solution of per cent strength. This mixture is applied to a support in the usual manner.

For brightening a 5 per cent solution of oxalic acid isused. The particles of ferric hydroxide should not be too small in size, a diameter of about 0.1-1 a gives satisfactory results. I If, for instance, the ferric hydroxide is produced in the gelatine by precipitation, the ferrie hydroxide is on account of its high grade of dispersity too less resistant to the fixing bath.

Example 2.--1000 ccm. of a gelatine solution of 7 per cent strength are mixed with 20 ccm. of a solution of 10 per cent strength of Benzolichtgelb R L (ci. Fierz-David Knstliche organische Farbstoie 1926, page 168) in water. Hereon 12 ccm. of a normal solution of barium chloride is added by dropping whereat the insoluble barium salt of the dyestui is formed.

For brightening a solution of sodium hydrosulfite is used, a few drops of glacial acetic acid being added immediatelyl before use.

Example 3.- grams of gelatine and 8.4 grams of calcium chloride are dissolved in 100 ccm. of water. To this solution there is added a solution of 10 grams of ammonium oxalate in 200 ccm. of water at 40 C. while stirring.

The mixture forms after washing with water and casting an emulsionlayer enabling retouching. The turbidity can be removed by hydrochloric acid of 2 per cent strength.

Ea'mplefi'l'o 1000 ccm. of a gelatine solution of 10 per cent strength there are slowly added 200 ccm. o a solution of mastic in alcohol of 20 per cent strength while stirring. After drying the emulsion forms a dull layer of gelatine containing small drops of mastic.l vThis layer allows both darkening retouches with graphite or the likematerial, and brightening retouches by removing the resin with alcohol.

The invention is illustrated in the accompanying drawing in which Figs. 1 to 3 show sections through photographic materials, according to this invention on an enlarged scale.

Fig. 1 shows a photographic material having a layer containing small particles and being capable of brightening retouches arranged on the jrear side.

Fig. 2 shows a photographic material having a layer containing small particles and being capable of brlghtening retouches arranged between the support and the light sensitive emulsion layer.

Fig. 3 shows a photographic material having the material enabling brightenlng retouches incorporated in the light sensitive emulsion layer.

I do not wish to limit my invention to the iorel going examples nor to the specic details given therein. Numerous other embodiments are possible and I contemplate as included within my invention all such modifications and equivalents as fall within the scope of the appended claims. As a rule the concentration of the material allowing brightening retouches should never be so high as to impair copying of the negative. Besides the coloring or darkening compounds mentioned above a great number of other azo dyes and organic or inorganic pigments is suited for the purpose in question. The chemical qualities of such compounds i. e. their fastness against the action of the photographic baths and their capability of being rendered colorlessV or being removed from the binding agent are well known to every chemist skilled in theart and a few simple comparative experiments should be made in order to determine the best kind 1of color and the best reagent or solvent to be used forlbrightening eiects.

What I claim isz- V1. A process of applying brightening retouches to a photographic material which comprises linely distributing in a light sensitive layer of said photographic material a compound resisting the photographic baths and diminishing the transparency to light of said layer, and partly clearing said layer by a chemical reagent in conformity with parts of a picture produced in said "layer that shall receive a greater transparency.

2. A process of applying brightening retouches to a photographic material which comprises nnely distributing in a light sensitive layer of said photographic material a compound selected from the group consisting of inorganic and organic pigments resisting the photographic treating baths, and partly clearing said layer by a chemi- 5 cal reagent in conformity with parts of a picture produced in said layer that shall receive a greater transparency.

3. A process of applying brightening retouches to a photographic material which comprises iinely distributing in a light sensitive layer of said photographic material an azo dye resisting the photographic treating baths, and partly clearing said layer by a chemical reagent in conformity with parts of a picture produced in said layerthat shall receive a greater transparency.

4. A process of applying brightening retouches to a photographic material which comprises ilnely distributing in a layer of said photographic material ferrie hydroxide and partly clearing said layer with a solution of oxalic acid of 5 per cent strength.

5. A process of applying brightening retouches v to a photographic material which comprises nely distributing in a layer of said photographic materialzBenzolichtgelb R L, and partly clearing said layer with a solution of sodium hydrosulte.

6. A process of applying brightening retouches to a photographic material which comprises finely distributing in a layer of said photographic material mastic, and partly clearing said layer with alcohol.

KARL KIPPHAN.

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