GB483020A - Improvements in colour photography and kinematography - Google Patents

Abstract

483,020. Colour photography. TRUECOLOUR FILM, Ltd., DOLGORUKI, E. SANDERS-, and REINDORP, J. H. Oct. 9, 1936, No. 27434. [Class 98 (ii)] A multi-colour photographic record is produced on exposed material, having three superposed silver halide emulsion layers and intermediate filter layers not decolorized by developing baths, by developing silver images in all the layers, subjecting the two outer layers successively to reversal exposure by light of such composition that it is prevented by the filter layers from reaching the intermediate layer, successively colour-developing differently coloured reversed images in the outer layers, re-exposing the material to light to obtain a reversal exposure in the intermediate layer, and colour-developing the intermediate layer to another colour, the filter layers being rendered colourless at any stage following the colour development in the two outer layers. As shown, the material comprises a celluloid or paper base 1, with blue, red and green (or blue, green and red) sensitive emulsion layers 2, 3, 4 and intermediate filter layers 5 coloured yellow with the free base of Auramine. The emulsion layers may contain restraining filter dyes. An antihalation layer 6 comprises a colloid layer containing neutral carbon black or a water-soluble black dyestuff. The exposed material is developed in a developer which may contain potassium thiocyanate, and the undeveloped part of the latent image is destroyed with cupric bromide or chloride. The material is cleared with sodium bisulphite solution and washed, and if necessary the sensitivity of the material is restored by treatment with dilute sodium sulphite solution. The material is re-exposed to blue light through the support and developed to blue-green by a colour developer containing p-aminodiethylaniline and 2 : 3 : 4-trichlornaphthol. The material is washed, exposed to blue light through the front, and developed to yellow in a colour developer containing p-aminodimethylaniline and p-nitroacetoacetanilide. The material is exposed to strong white light, or is treated with dilute acetic acid to destroy the filter layers 5 and exposed to blue or white light, and the latent image in layer 3 is developed to magenta in a colour developer containing paminodiethylaniline and p-nitrobenzylcyanide. The silver images are removed by Farmer's reducer or by bleaching and fixing. The material may be treated as described in Specification 465,765. When the base 1 is paper, emulsions containing half the normal amount of silver are used. The process may be used in copying coloured positive records. Specifications 440,032, 444,198, and 451,699 also are referred to.