GB455128A - Improvements in and relating to colour photography - Google Patents

Abstract

455,128. Colour photography. KODAK, Ltd., Kingsway, London.-(Eastman Kodak Co. ; 343, State Street, Rochester, New York, U.S.A.) June 1, 1935, No. 9734/36. Divided out of 447,092. [Class 98 (ii)] A photographic record in the minus colours of the original is produced by converting into coloured image records superimposed latent image records of different colour sensations covering substantially the whole of the visible spectrum which have been produced respectively in at least three gelatine-silver halide emulsion layers inseparably coated on the same side of a single support by a single exposure of all the layers from one face whereby such latent images lie accurately superimposed and mostly in the corresponding strata of each layer, and submitting the emulsion layers without reversal of the images therein to a colour developer whose penetration is so controlled as to restrict the development to an upper layer or layers. The film, after exposure, is slightly tanned, developed in an ordinary developer, fixed, washed, and bleached with an ammoniacal ferricyanide or hydrobromic acid oxidizing bath. The images are, if necessary, rendered redevelopable by exposure'to light and the uppermost image is developed to minus blue in a developer containing p-aminodimethylaniline sulphate, 4-nitroacetoacetanilide and iso-propyl alcohol as loading agent, then the next image is developed to minus green in a developer containing 2-amino-5-diethylaminotoluene hydrochloride, potassium thiocyanate, p-nitrophenylacetonitrile, and isopropylalcohol, and the bottom image is developed to minus red in a developer. containing p-aminodiethylanilinemonohydrochloride, potassium thiocyanate, and m-hydroxydiphenyl, the film being thoroughly dried between each development. The metallic silver is removed by Farmer's solution and the film is washed and dried. In a modification, the image in the top layer only is redeveloped to silver, the images in the remaining layers are colour developed by controlled penetration, and the image in the top layer bleached and colour developed. The sensitive layers may also be on plates or paper, and the films may carry a sound track. Specifications 245,198, [Class 98 (ii)], 376,838, 427,518, 447,092, 453,233, and 454,622 are referred to.