Patent GB-516059-A (GB)
Title: Light-sensitive material for colour photography
IPC: G03C7/28
Filed: 1938-06-14
Abstract: 516,059. Colour photography. GASPAR, B. June 14, 1938, Nos. 17634, 17804 and 18035. [Class 98 (ii)] Multilayer material comprises three lightsensitive silver halide emulsion layers and at least one non-light sensitive coloured layer in immediate contact with one silver halide layer and dyed with a reducible, dye resistant to ordinary processing baths but locally destructible in the presence of the silver image, one outside layer being a silver halide emulsion 'layer not containing an image-forming dye and the other a coloured non-light-sensitive layer. A material referred to but not an example of a material according to the invention comprises blue, green and red sensitive silver halide emulsion layers with a filter layer between the blue- and green-sensitive layers dyed yellow with a. dye resistant to processing baths but locally destructible in the presence of a developed silver image on treatment with an appropriate solution. The support or a colourless separating layer is placed between the filter layer and the green-sensitive layer. The green- and redsensitive layers may contain dye-forming substances or dyes. A material according to the invention comprises a front blue - sensitive emulsion layer, a gelatine layer coloured yellow with Chrysophenine G, a thin colourless gelatine layer, a green-sensitive silver halide emulsion layer, a gelatine layer coloured magenta with Anthosine BN, a colourless gelatin layer, a redsensitive silver halide emulsion layer, and a gelatin layer coloured blue-green with Brilliant Benzo Fast Green, which may be precipitated with salts of calcium or organic bases, The support may be in front of or at the rear of the material, or may replace one of the colourless gelatine layers. After exposure', development and fixing the material is treated with a dye - destroying solution containing an accelerating substance and silver is removed The coloured picture produced may be printed on to similar material, the concentration of the dyes being lowered if an opaque support such as paper is employed. A sound image may be printed on the material and processed to colour or to black silver. Another material for printing comprises a coloured outside layer,- two lightsensitive layers, two coloured layers and a lightsensitive layer. The support may be between the two neighbouring light-sensitive layers or between 'the two coloured layers or may be behind one of the outside layers. The coloured layers are coloured with yellow, magenta and blue-green dyes. The light-sensitive or the coloured layers may contain removable filter dyes. Six examples of such materials are given. In several of these the. sensitivies of the two outer silver halide emulsions are the same, the layers being either blue-sensitive or greensensitive, and the colouring of the coloured layers are not always complementary to the sensitivis of the adjacent silver halide emulsion layers. The materials are printed from opposite sides of the support, or the rear layer may be infra-red sensitive and all the layers printed from the same side of the support. The material may be used for printing from black-and-white component images or multicolour positives. The dye-destroying solution may contain potassium bromide, concentrated sulphuric acid and 2:3- dimethylquinoxaline. The relative thickness of the coloured layers may be adjusted to the relative bleaching speed of the dyes, a method of ascertaining this being described. Specifications 416,566, 416,660, 421,727, 514,955, and 516,059 are referred to.