GB1494010A - Method of forming photographic colour images in photosensitive silver halide materials - Google Patents

Abstract

1494010 Reversal processing photo-sensitive silver halide colour material EASTMAN KODAK CO 3 July 1975 [10 July 1974] 28093/75 Heading G2C An imagewise exposed photographic material comprising a support bearing at least one photosensitive silver halide emulsion layer and contained therein or in one or more adjacent layers a non- diffusible primary aromatic amino silver halide colour developing agent and a non-diffusible colour coupler is (1) treated with an alkaline non-cross-oxidizing silver halide developer composition (which comprises a black-and-white developing agent which becomes oxidized when it develops exposed silver halide to silver and will not oxidize the colour developing agent) to produce a silver image, (2) fogged, (3) treated with an alkaline cross-oxidizing silver halide developer composition (which comprises a black-and-white developing agent which becomes oxidized when it develops exposed silver halide to silver and crossoxidizes the colour developing agent) to produce both silver and dye in the fogged areas; (4) bleaching the developed silver with a bleach solution having an oxidation potential such that it will not oxidize any remaining colour developing agent and (5) fixing. The non-cross-oxidizing developing agent may be ascorbic acid or a 5-amino- or 5-hydroxypyrimidine e.g. 2-methyl-4-amino-5, 6-dihydroxypyrimidine. Fogging may be effected by exposure to light or chemical fogging. The crossoxidizing developing agent may be 1-phenyl-3- pyrazolidone, 1-phenyl-4, 4-dimethyl -3-pyrazolidone or 4-hydroxymethyl-4-methyl-1- phenyl-3-pyrazolidone. Bleaching is preferably effected with a single bleach-fix bath containing sodium or ammonium thiosulphate and complexes of trivalent iron and ethylenediamine tetraacetic acid. In Example 2 the bleach-fixed material is washed and then placed in an aqueous stabilizing bath (pH 12À0) containing 0À5 wt. per cent cetyltrimethylammonium bromide, washed and dried.