GB480287A - Colour photography and kinematography - Google Patents

Abstract

480,287. Colour photography. TRUECOLOUR FILM, Ltd., DOLGORUKI, E. SANDERS-, and REINDORP, J. H. Oct. 9, 1936, No. 27435. Drawings to Specification. [Class 98 (ii)] Two exposed superposed silver halide emulsion layers or strata are developed to silver images and fixed, the upper image bleached to silver iodide and the lower image to silver ferrocyanide or other redevelopable salt, the lower image colour developed, and the upper image coloured in any suitable manner. The iodine bleaching solution comprises 0À4 per cent iodine and 6 per cent potassium iodide, and is followed by a sodium sulphite stop bath. The other bleaching solution is an ammoniacal solution of potassium ferricyanide. A magenta colour developer comprises diethylparaphenylenediamine hydrochloride and p-nitrobenzylcyanide with the usual additions and isopropyl alcohol. The silver iodide image may be toned blue-green with an acetic acid solution of Iodine Green followed by treatment with silicotungstic or phospho-tungstic acid. The silver and silver iodide in the two layers may be removed by Farmer's Reducer. In a modification, the silver iodide layer is re-developed to silver by an alkaline amidol developer, coated with pigmented gelatine, and treated with a bath bleaching the silver and hardening the contiguous gelatine. The unhardened gelatine is removed with warm water, and the silver and silver salts removed. Alternatively, the re-developed silver image is rebleached with a ferricyanide bleacher and colour-developed. Before treatment of the silver iodide image, the silver in the lower layer may be bleached to silver ferrocyanide, which is dissolved out by sodium sulphite. The process may be applied to different strata of a single emulsion layer, or to films having two superposed layers on one side of the support and one or two layers on the other side of the support. The layers on the opposite sides of the support may be processed by flotation, or a varnish layer, which may also serve as the anti-halation layer, may be applied to one side of the material. In a three layer film after development and fixing, the upper of the two superposed images may be converted to silver iodide, and the other two images differentially colour-developed. The silver iodide image is then coloured. Specifications 377,706, 382,320, 465,090, and 480,251 are referred to.