GB499306A - Improvements in or relating to the preservation and surface regeneration of photographic films - Google Patents

Abstract

499,306. Renovating photographic films. STOCK, F. J. J. June 14, 1937, No. 16511. Convention date, July 1, 1936. [Class 98 (ii)] Scratches and other injuries are removed from either surface of the film, and the film is also protected, by treating it first with solvents of the film material, mixed with softening agents which are not solvents, to render the surface layer liquid, and thereafter, while the surface is still liquid applying a coating of hardening substances having the same optical properties as the film material. The solvent liquid preferably comprises a mixture of non-volatile and highly volatile solvents. For treating the celluloid side of a film a solvent liquid consisting of acetone mixed with dichlorhydrine, amylalcohol, camphor or triphenylphosphate may first be applied, and thereafter a coating liquid is applied consisting of collodion, celluloid or a cellulose ester, and etheralcohol. For treating the gelatine side, the solvent liquid may consist of ethylene chlorhydrine, urea and water, and the coating liquid of polyvinyl alcohol, alcohol, ethylene chlorhydrine and water. Specifications 243,752 and 486,360, [both in Class 98 (ii)], are referred to. The Specification as open to inspection under Sect. 91, states also that, alternatively to the coating liquid, a powder may be sprayed on which dissolves in the swelling agent, e.g. an acetyl cellulose film may be treated with acetone and lactic acid ethyl ester, and then sprayed with powdered acetyl cellulose. This subject-matter does not appear in the Specification as accepted.