GB466710A - Improvements in colour photography - Google Patents

Abstract

466,710. Colour photography. TRU COLOUR FILM, Ltd. Nov. 28, 1935, No. 33007. Convention date, Dec. 13, 1934. [Class 98 (ii)] The photographic silver image of a colour record print is dye-toned with dye in association with a thio-amino compound, such as thiocarbamide, thiosinamine, cystein, or thioacetamide, whereby the image is brought to a condition such that colour can be transferred therefrom to a separate surface by contact with the latter. The colour record prints may be made on sensitized paper or celluloid either from a multicolour - screen or other coloured negative or from two colour component negatives, one recording the violet to yellow part of the spectrum and the other the red to green part. The print from the red component negative is iron-toned blue, while the. print from the violet component negative is bleached in a cupric chloride acetic acid bath and dye-toned red-yellow in a bath containing acid fuchsin, tartrazine, and thiocarbamide and then washed. Alternatively the bleached image may be treated first in a thiocarbamide bath and then in a dye bath with or without thiocarbamide. The blue-toned print is immersed in a transfer bath of potassium bromide containing nitric acid. The red-yellow print is registered therewith and the two prints are squeezed together with or without heat. The transfer may be effected prior to toning the blue print. The print from the red component negative may be dye-toned blue in a bath containing Patent Blue L and thiocarbamide, and colour transferred from both prints on to a surface previously treated in either an acetic acid or an acetic acid and thiocarbamide or a chrome alum bath, with or without potassium bromide. The general dyestain produced may be locally revived by dilute acid for retouching purposes. The yellow parts may be brightened with dilute ammonia, sodium carbonate, or soluble sulphite, or lightened by chlorine. The prints may be fixed in hypo before or after transference. Three colour component prints may be made, and colour successively transferred from the red and the yellow dye-toned prints to the blue iron-toned print, or all may be dye-toned and colour transferred to a separate surface. The prints may be stretched, shrunk to permit of registration by immersion in a softening or hardening bath or hot or cold water. A grey key image may be produced by partial re-development of the iron-toned print in acid amidol. The final prints may be made on to a base having emulsion on one or both sides, or separate transparent bases finally combined in register may be used. The water employed should have a pH value of 6. Specification 400,251 is referred to.