GB427518A - Improvements in colour photography - Google Patents

Abstract

427,518. Colour photography. KODAK, Ltd., Kodak House, Kingsway, London.- (Assignees of Mannes, L. D., and Godowsky, L. ; Kodak Park, Rochester, New York, U.S.A.) Sept. 21, 1933, No. 18934/34. Convention date, Sept. 21, 1932. Divided out of 427,472. [Class 98 (ii)] Relates to the differential processing of superimposed layers containing different colour-sensation records on the same side of a single support by restricted penetration of a bleaching bath or a developing bath and consists in controlling the penetration by the use of water-soluble loading-agents, by the provision of a gelatine layer between the emulsion layers, and by the use of stop baths. Thus a film comprising two emulsion layers separated by a gelatine layer, colour-developed to a minus-green, as described in Specifications 427,516 and 427,520, is subjected to the action of a chromic acid-bromide bleach bath loaded with methanol and the action is terminated by the use of a stop bath consisting of ammonia with or without sulphite and methanol. In an alternative method, wherein a two-layer film is exposed, developed, fixed and bleached, as described in Specification 427,472, the upper layer only is redeveloped by an hydroquinone or amidol developer loaded with sodium sulphate and development is arrested by immersion in an acetic acid stop bath maintained at a very low temperature, e.g. 0-5‹ C. After colour - developing the lower layer to a minus-green, the upper layer is bleached in a ferricyanide bath loaded with sodium sulphate and the action is arrested by a stop bath of hydroxylamine or hydrazine and ammonia. Specification 376,838 also is referred to.