GB730122A - A process for the production of photographic images in natural colours or a mixed shade by the subtractive three-colour process - Google Patents

Abstract

730,122. Colour photography. PAPADAKIS, S. May 22, 1953 [May 23, 1952], No. 14465/53. Class 98 (2). A film of cellulose ester such as the nitrate acetate or butyrate is sensitized in an alkaline solution of a diazosulphonate and a coupling agent for the blue colour component in a volatile solvent, exposed behind the corresponding negative, washed in alcoholic caustic soda solution to remove unaffected sensitizer and washed as in running water to remove the alcoholic caustic soda; and then these operations are repeated using, in either order, sensitizing solutions of a diazosulphonate and a coupling agent for the red and yellow colour components, and using the corresponding negatives to produce the colour images; or, alternatively, using the same orthochromatic negative for all three operations to produce a grey-black image. The sensitizing solutions may be a mixture of acetone, methyl alcohol and amyl acetate with a little water and caustic soda to provide alkalinity containing, for the blue colour the diazosulphonate of 5-amino-2- benzoylamino - 1,4 - diethoxybenzol with the meta-nitranilide of 2,3-oxynaphthoic acid as coupler, for red the diazosulphonate of 1-amino- 2,4-dimethylbenzol with the same coupler, and for yellow the diazosulphonate for red with 1- phenyl - 3 - methyl - 5 - pyrazolone.