GB217557A - Improvements in or relating to colour photography - Google Patents

Abstract

217,557. Dufay, L., (Assignee of Compagnie d'Exploitation des ProcÚdÚs de Photographie en Couleurs L. Dufay). June 11. 1923, [Convention date]. Drawings to Specification. Colour photography.-Relates to a process for producing multicolour screens, in which a celluloid or like support, superfieially dyed with one colour, is partially covered with resists, and the celluloid is decoloured at the unprotected parts, which are then dyed with a second colour, so that, on removing the resists, a two-colour screen results. According to the invention (1) the twocolour screen so produced is coloured throughout with a third colour, and (2) further resists are applied, followed by decolouring and dyeing to produce a four-colour screen. In an example, a two-colour screen is first produced by dyeing one side of the film uniformly blue, and printing thereon a series of resist lines in fatty ink. A red alcoholic colouring-bath is applied which destroys and replaces the blue dye-stuff in the unprotected. spaces. The resist is dissolved away, and a yellow alcoholic dye containing a decolouring agent is applied to the whole surface, converting the blue lines into green, and the red into orange. If a four-colour screen is desired, a fresh series of resist lines is printed on the two-colour screen at any angle to the first set of resist lines, and a blue-violet colouring-bath containing a developing agent is applied which destroys and replaces the yellow in the unprotected parts, which then exhibit the colours blue-violet and red-violet in alternate spaces. On dissolving away the resist, a four-colour screen comprising these, colours together with green and orange is obtained. Suitable dyes are rhodamine B or rhodamine N6J, malachite green or auramine, methylene blue, and crystal victoria or crystal violet. The decolouring agents may be caustic potash or soda. The Specification as open to inspection under Sect. 91 (3) (a) states that the screen may be coated with emulsion, and may be produced in long lengths for kinematography. This subjectmatter dees not appear in the Specification as accepted.