| 摘要 |
536,831. Pictures. SANDERS, L. S. Nov. 27, 1939, No. 30901. Convention date, Dec. 1, 1938. Drawings to Specification. [Class 11] [Also in Group XX] Drawing material suitable for the production of representations for use as camera copy comprises a transparent or opaque support, a chemically developable layer, a thin transparent or translucent gum or resin layer soluble in or penetrable by the developer, and a coating of transparent or translucent material insoluble in and penetrable by the developer on the film and having a multiplicity of spaced openings. A dull surface transparent or translucent coating insoluble in but penetrable by the developer may be provided. In an example, a suspension of mercurous chloride in gelatine containing also sodium metatungstate and formaldehyde is applied to a paper support. A thin film of gum or resinous material is applied, the gum being benzoin, ammoniac, sandarac, galbanum, olibanum. mastic, copal and dammer. A varnish film insoluble in and impenetrable by the developer is applied by printing to leave the small spaced openings. The surface coating comprises either (a) an aqueous-alcoholic solution of gum mastic and gum dammer, (b) an aqueous-alcoholic solution of cherry gum and gum galbanum or (c) an aqueous solution of albumen followed by after-treatment with sorbitol. The cherry gum may be replaced by other water soluble substances. The developers are applied with a brush by an artist. The slow developer employed first comprises an aqueous solution of thiourea and sodium sulphate. The fast developer comprises an aqueous solution of thiourea, ethylenediamine, phenolphthalein (or o-cresolphthalein) and urea, to which has been added a small quantity of alcoholic shellac solution. The solution is coloured a dark red which disappears on drying. The ethylenediamine may be replaced by alkali hydroxides or salts, ammonia, propylenediamine, monoethenolamine, benzylamine, or piperidine. The developable substance may comprise silver chloride which is developable by reducing agents or amines. A silver chloride, bromide, or iodide photographic printing paper may be exposed, photographically developed and fixed and bleached in mercuric chloride solution to give suitable developable material. Material having a transparent support may be used for tracing particularly for use in the production of colour plates, or when developed may be used as photographic negatives. Specification 522,782, [Group XXXV], is referred to. |
