Patent GB-191505100-A (GB)
Title: Improvements in the Manufacture of Monochrome and Multi-colour Kinematograph Films.
Inventor: THORNTON JOHN EDWARD
IPC: G03C7/22
Filed: 1915-04-01
Abstract: 5100. Thornton, J. E. April 1. [Cognate Applications, 7183/15 and 10,768/15.] Kinematograph picture films ; photo-mechanical printing-surfaces. - Monochrome or multi-colour kinematograph films are printed wholly or in part photo-mechanically by means of long continuous printing-belts which have grainy or broken tone images and are provided with perforations or notches which are used in conjunction with perforations in the film to obtain accurate register. The printing belts may be prepared by any known process for producing relief, surface, or intaglio printing-surfaces and may be of copper, steel, brass, aluminium, or other metal, or of textile material or celluloid. In the case of relief or intaglio belts, the printing-surface may consist of hardened gelatine and may be prepared by the Leimtype process either as described in Specification 37/87 or modified by making the base of the belt flexible, and by grooving or perforating it so as to promote the adhesion of the gelatme which is applied to one or both sides. When the celluloid is used as the base of the belt, it may be etched by an air blast or a sand blast charged with a solvent such as amyl acetate after the washing out of the film. Cast or moulded reproductions of the printing-belt in celluloid, gelatine, or rubber, may be made. In photo-litho and like processes a grained metal or celluloid belt is used. Other surface processes which may be used include the collotype process, using a fatty or stiff water-colour ink, an improved collotype process in which the belt is perforated and fed with glycerine and water from the back, and an improved hydrotype process in which also the belt is perforated and a watery or spirit ink is supplied from the back. In both the improved collotype and bydrotype processes, grain may be formed automatically by reticulation of the gelatine, by the use of a screen, or by graining the base of the belt. In all processes for preparing the belts, the gelatine may be sensitized with silver bromide and hardened after development &c. by an oxidizing-bath of the ozobrome type. Two or more printing-belts may be produced from the original picture film or from each colour record film having different exposures, and by printing from them in succession in the same or different shades of ink a long scale of gradation and better colour effect may be obtained. The grain of the pictures may be rendered invisible when the pictures are projected on to a screen by so preparing the belts that the incidence of the dots or lines is different in successive pictures in the manner described in Specification 16,899/14, and in addition, when two or more belts are produced from each original film, by placing the grain-producing screen in different positions for the exposures for each particular picture. Some of the belts for printing the superimposed pictures may be prepared by different processes from the others, and photomechanically prepared belts may be used to print over grey or black key pictures cr pictures in one of the elemental colours photo-chemically printed, such pictures being cyanotype, toned silver, carbonbichromate, or pinatype-dyed bichromate prints. The film upon which the pictures are printed may be made of the ordinary celluloid or cellulose materials usually employed, or may be a non- waterproof, non-inflammable colloid film either of gelatine or a mixture of colloids. The colloid films may be hardened, or have fibrous cellulose incorporated in them to secure increased strength, or contain salts which render them more fireresisting. They may be prepared with a surface of soft gelatine &c. to make them more receptive of the printing-ink, and graining-material maybe incorporated in this surface. Any suitable waterproof varnish may be applied to them. Methods of performing the operations in the preparation of colloid films are described in the Specification. According to the Provisional Specifications, the film for projection may have a paper base.