GB402619A - Toning process particularly for toning the red color component image for multi-colorphotography - Google Patents

Abstract

402,619. Photographic processes. JASMATZI, A., 2, Neuer Markt, Vienna. Jan. 31, 1933, Nos. 3043 and 3044. Convention dates, Feb. 2, 1932 and Jan. 21, 1933. [Class 98 (ii).] Toning; colour photography.-A red-toned print, more particularly the red component of a colour photograph, is produced by substituting, for the silver of an image produced in an ordinary silver halide emulsion layer, nickel dimethylglyoxime or a homologue thereof. One method, employing a nickel salt which reacts with dimethylglyoxime &c., consists in first converting the silver into a lead salt by treatment in a bath of lead nitrate and potassium ferricyanide ; then converting the lead salt into a nickel salt by treatment with nickel sulphate ; and finally toning the image red by treatment with dimethylglyoxime &c. Another method, employing a nickel salt which does not react with dimethylglyoxime &c., consists in toning the silver image directly with a bath containing a complex nickel salt such as potassium nickel cyanide, dimethylglyoxime, and ammonia ; but the action is slow, and quicker results are obtained by first converting the silver of the image into silver halide or silver cyanide, or by adding to the toning bath a salt which will effect this conversion, potassium ferricyanide being specially mentioned. A modified tone for the two-colour process may be produced by bleaching the image in a bath of lead nitrate and potassium ferricyanide, toning it red by treatment with potassium nickel cyanide and dimethylglyoxime, and then changing the tone to orange by treatment with potassium bichromate solution. A three-colour picture may be produced by printing the three components on silver halide emulsion layers coated on a strippable base of pergamyn or other diaphanous paper. The blue component is first bleached with a bath of lead nitrate and potassium ferricyanide and then toned yellow with potassium bichromate; the red component is toned blue with a bath of potassium ferricyanide and a ferric salt and the green component is toned red by one of the methods described above. The toned images are transferred in superimposition on to a final support as of baryta paper. The colours may be modified before transfer, if examination of the prints in loose superimposition shows this to be desirable, as by weakening the yellow or blue image in known manner, or by weakening the red image by bathing it in a weak, preferably organic acid other than acetic acid.