GB191415648A - Improvements in and relating to the Process of Producing Kinematograph Films in Natural Colours. - Google Patents

Abstract

15,648. Cox, S. J. June 30. Colour photography.-A process is described, more particularly applicable for kinematograph films, in which two colour images are first produced in the original gelatine coating of the support, one of these being a blue print, and the other produced by resensitizing the same gelatine layer and exposing a second colour negative. For a three-colour film, the third colour is obtained by recoating the film and printing from the third colour negative. The positive may be printed from three separate colour negatives, or from a single negative having recurring series of colour negatives. The blue print may be obtained by toning a bromide print, and in developing and toning the print, materials should be avoided which tend to harden the gelatine. Thus amidol or ferrous oxalate could be used for developing, and as weak a solution of ferricyanide as is possible in the toning process. After the blue image is formed, the gelatine is resensitized with a bichromate solution and printed from a positive of the red-printing negative. The chromate salt is removed by washing and, if necessary, by an acid sulphite of potassium bath, and the film immersed in, say, pinatype red, an excess of ammonia being avoided. For a third colour, this two-colour picture film is recoated with a bichromated colloid and printed from a positive of the third colour printing negative. Where albumen is used as a colloid, it is desirable to coagulate the albumen stratum when dry by the application of dilute alcohol.