GB245163A - Improvements in the production of pictures by the dye-transfer process - Google Patents

Abstract

245,163. Arx, R. von. Dec. 24, 1924, [Convention date]. Colour photography; photo-mechanical printing- surfaces.-A process of producing, by dye transfer, monochrome or multi-colour prints having identical colour values consists in treating a silver positive, or each of a set of colour-record silver positives, with a substance or substances so as to convert the silver of the image into a mordant, dyeing the image with a dye having an affinity for this mordant, and transferring the dye picture by placing the positive, in moist contact, with or without pressure, with a copy sheet which in itself, or by virtue of a mordant contained therein, has a greater affinity for the dye than the mordant in the positive, so that a complete transfer of the colour results. The sheet may be of collodion or other nitro-cellulose derivative, or of gelatin containing a mordant. In the case of two-colour or three-colour pictures the colourrecord positives may be originals or reproductions from a multicolour screen-plate negative. The mordant in the copy sheet may be removed therefrom after the picture has been transferred to it. The positives may be dyed repeatedly to make repeat pictures. An example is described in which a silver positive image is converted in a toning bath containing copper sulphate, neutral ammonium citrate, potassium ferricyanide, and ammonium carbonate, into a mordant comprising the ferrocyanides of silver and copper. The mordant image is washed and immersed for 10 minutes in a dye-stuff such as methylene blue. The dye picture is transferred by contact in moist condition, either to a plain collodion sheet, or to a sheet of paper coated with gelatin containing cuprous thiocyanate as mordant, which may remain in the copy or be removed.