Patent GB-516719-A (GB)
Title: Improvements in colour prints by multiple colour development
IPC: G03C7/30
Filed: 1938-04-09
Abstract: 516,719. Colour photography. SCHINZEL, K., and SCHINZEL, L. April 9, 1938, No. 10911. Convention date, April 10, 1937. [Class 98 (ii)] Three-colour copies are produced from threecolour originals or intermediate records on to a light-sensitive emulsion or emulsions on a single support by exposing each colour component image from the same side on to the copying material and colour developing without shift or with only microscopic shift in registration before the next component image is printed. The copying emulsions may be shrink-proof and hardened, and antiswelling agents may be added to the developing baths. The original may be projected vertically on to the copying material fastened by a waterproof adhesive to the inside bottom of a developing tank, or may be projected horizontally on to the copying material fastened to a wall, development being effected by a sponge. A multicolour screen original may be fastened to a sensitive film, and on the emulsion side of the latter is tightly put a frame to serve as a container for the processing solutions and exposure is effected from below. Potassium bromide or nitrobenzimidazole may be added to the developers, and potassium thiocyanate to the second and third developers. Subtractive originals may be produced on three - layer material containing or not containing colour formers. A multicolour original may be cemented to a panchromatic film and successively exposed by means of filters of the same colour as the screen dystuffs, each exposure being followed by colour development The metallic silver is removed with hydrogen peroxide and the remaining silver halide reduced to silver or made developable by exposure or fogging agents and developed to a black image. Alternatively the development is effected with a fogging black coupling developer containing a high proportion of caustic alkali, ammonia, or aliphatic amine. The coupling component may be eugenol or 1:5-dihydroxynaphthalene. The silver halide may also be converted to silver sulphide or, if it is silver chloride, converted into an opaque metal compound or into a mordant for a black or dark-brown dye. A positive multicolour screen film is projected on to an emulsion coated on paper or regenerated cellulose film fastened to the bottom of a developing frame, and development effected without moving the assembly. A lenticular film may be similarly printed by attachment of a sensitized film to the emulsion side thereof and effecting exposure by successive uncovering of the three filter diaphragm bands. An intermediate lenticular film may be produced from a lenticular negative by printing and developing by black coupling development and successively re-exposing and colour developing with final removal of silver. Subtractive copies may be made by microscopic displacement of the copy during each partial exposure and development in complementary colours. Oblique transmission of light from the original may replace microscopic displacement. The original may be made on a film comprising a lenticular support coated on its plain side with an orthochromatic emulsion layer, a decolourable red filter layer, and a red sensitive emulsion layer. The taking filter has yellow and purple stripes. The emulsions may contain non-diffusing coupling components and may be processed by colour development, all silver and residual silver halide being finally removed. In copying exposure is first made with yellow light on to orthochromatic film, which is developed blue-green, then the half of the' diaphragm corresponding to the yellow filter is opened, the copy moved slightly and developed yellow, and finally the other half of the diaphragm is opened, the copy moved and developed magenta, and finally all silver and residual silver halide removed: After the first and second colour development the reduced silver may be rehalogenized with potassium ferricyanide and potassium bromide with or without ammonia. A sensitizing dye may be added to the rehalogenizing bath. Mixtures of high and low sensitive or of differentially colour sensitive emulsions may be used. A one- or twolayer material of the mixed grain type may be used. A one-layer three-mixed-grain material containing insoluble coupling components mav be sensitized for extreme red or infra-red, orange-yellow, and blue-green or red, yellowishgreen (both silver chloride), and blue-green (silver bromide). Thick layers sensitized in strata may be used. The bottom layer of twolayer material may be of different colour sensitivity or of higher sensitivitv. or may be a collodion emulsion or strongly hardened. or may comprise a mixture of differentially sensitized emulsions or grains or may be differentially sensitized in strata. Copying from false colour originals may be effected Specifications 475.786, 498.869, 498.870, 498,871, 499.185, 500.611, 500.826, 503.752, 503.814, 503,818, 503,821, 530,823. 503,824, 503,825, 503,826, 503,827 and 503,941 are referred to. The Specification as open to inspection under Sect. 91 comprises also the addition of sugars to alkaline developers and colour developers to retard atmospheric oxidation. Emulsion binders comprise collodion, cellulose acetate or ethers, agar-agar, and polyvinyl alcohol. Aritiswelling agents for addition to colour developers or wash water comprise sodium carbonate, potash, sodium sulphate and trisodium phosphate. Dilute alcoholic developers may be used. The residual silver halide in prints may be developed to a whitish image, or converted to silver ferrocyanide and either reacted with metal chlorides to give coloured ferrocyanides or converted to mordants for gray or dark brown-dyes. Kinematograph films may be joined in printing by " thermo-cement," or rubber projections may fit into perforations or metal springs on a transport film may project therethrough and be provided with caps. Tin strips or metal clamps may be used. The emulsion side of a lenticular film may be coated first with fine-grain silver halide emulsion, then " Lippmann" emulsion, or a silver ferrocyanide emulsion, and the lenticular film is successively exposed through the screen. The lenticulations of a differentially colour developed lenticular print may be effaced by pressure or varnishing. Residual silver halide may be toned to a black silver sulphide image, or may be converted to undevelopable silver iodide while the successive colour development is being effected. The silver of a lenticular film may be converted to silver bromide or chloride and successively colour developed or dye-toned. A refraction grating may be used in projection printing. Lenticular films may be taken with objectives producing a cylindrically curved image. In lenticular film projection-printing apparatus, the two feeding mechanisms may be synchronized by scanning the two sets of lenticulations either mechanically, or by photoelectric cells, the edges of the lenticulations being filled with black dye in the latter case. A multicolour screen original taken with a removable taking screen may be printed using a black-and-white screen. A bipack film in which the upper layer has a two-c.olour screen may be converted to a subtractive colour picture by utilizing the lower film and successively exposing and colour developing. Lenticular bipacks including bipacks in which the rear support has two emulsion layers on the same or opposite sides thereof or three emulsion layers on the same side or distributed between the two sides, may be similarly processed, or may be first converted to a colour screen bipack, or may be used for printing on to a separate colour sensitized film. A two-layer film in which the upper layer carries a two-colour screen is similarly treated. A third less-sensitive emulsion such as a silver ferrocyanide emulsion or a zinc ferrocyanide emulsion convertible thereto may be employed. A bleacher for controlled diffusion comprises an alcoholic lithium ferricyanide or bromide. The image in the red sensitive emulsion may be developed by a differentially hardening developer or the developed silver may be treated to produce differential hardening, and is then treated with ultra-violet or infrared-absorbing substances. Lenticular two-layer material may be converted to material with one homogeneous coloured layer and one 'twocolour screen layer, or to a completely subtractive image. In the latter case a third emulsion layer of silver ferrocvanide, converted to silver bromide or chloride immediately before use. may be provided. Coupling components may be added to the emulsions. The lenticular two-layer material may be printed on to another film to give a subtractive print, more particularly if the original has coloured, including ultra - violet or infra - red absorbing, images. A blank lenticular film may be used in printing. Prints from subtractive three-colour originals or separation records on a single emulsion are described, and ultra-violet or X-rays or possibly infra-red rays may be used for printing. Silver halide may be sensitized to X-rays with the thorium salt of eosin. A large number of prints may be exposed at the same time. The silver images may be made opaque to the printing light by toning to lead, mercury or thorium ferrocyanide or by dyetoning. A lemon-yellow developer is a sodium carbonate solution of p-chlor-symm : m-xylenol. Silver bromide may be colour developed with a solution of a - naphthol - 4 - sulphonic acid and p-aminodimethylaniline in the presence of borax. Non-diffusing or hardly diffusing salts of sulphonic acids of high-molecular components added to the emulsion react with a colour developer containing borax. Printing may be effected on a layer containing three differently colour-sensitized emulsions using first strong red light until the corresponding emulsion is solarized, less strong yellow light and normal blue-green light. Residual latent images may be destroyed by acid p-phenylenediamine or potassium ferr