GB516606A - Manufacture of colour photographs - Google Patents

Abstract

516,606. Colour photography. GROVES, W. W. July 1, 1938, No. 19552. Convention date, July 1, 1937. Addition to 516,584. [Class 98 (ii)] A bi-pack material comprising one support bearing two silver halide emulsion layers sensitive to two different spectral regions and separated by a filter layer stable to the photographic baths, and another support bearing a single emulsion layer sensitive to the remainder of the spectrum is developed, and in the twolayer element the silver is dissolved out and the silver halide images are converted into colour images by means of separate exposures using the filter layer and monochromatic light. The filter dyestuff is bleached out after the production of at least one coloured image. The filter dyestuff may be 1 (para-sulphophenyl)-5- pyrazolone-3-carbonic acid-ethyl ester in a two layer element consisting of a blue sensitive layer and a green sensitive layer, the former layer being exposed to blue light and developed to yellow as in Specification 459,665. The green sensitive layer is developed to purple with diethyl-para-phenylenediamine and an isooxazolone. The red-sensitive single layer of the bi-pack is developed to a negative or by reversal to a positive, and either in black and white or in colour. The black and white developed image is toned or dyed in known manner. If one of the two superimposed layers is red-sensitive, it can be developed to blue green by using indoxyl or indoxyl derivatives. If the red-sensitive layer is alone on one side of the support, the blue green picture is produced by iron-blue toning. Specification 486,424 also is referred to.