GB1265844A - - Google Patents

Abstract

1,265,844. Intensifying photographic latent metal images. ITEK CORP. June 6, 1969 [July 11, 1968], No.28802/69. Heading G2C. [Also in Division C1] An invisible or partly visible latent metal image is physically developed by treatment with a solution of stannous ions and then, as a reducing agent, with a solution of chromous ions. Alternatively the chromous solution may be applied first. The stannous ion solution preferably contains anionic stannous complexes with halides e.g. SnCl 2 and NaCl and a strong acid e.g. HCl or H 2 SO 4 , and e.g. CrCl 2 in aqueous/alcoholic solution and is preferably made by reduction of a chromic salt solution. The blackness of the tin image is improved by adding phenols, sulphones, sulphoxides or sulphonates to the Sn or Cr solution and glue may be added to the Cr solution. Metal latent images which can be intensified are those of Ag, Au, Cu, Sn, Mg and Pd and latent images may be obtained by exposure of silver halide emulsions or of diazonium salt or diazosulphonate compositions, or preferably by exposure of a photoconductor, e.g. TiO 2 , followed by treatment with a metal salt solution, e.g. silver nitrate and optionally trisodium nitrilotriacetate, and then, with a reducing agent and optionally a fixing agent. Other photoconductors specified are ZnO, Sb 2 O 3 , Al 2 O 3 , ZrO 2 , GeO 2 , In, SnO 2 , CdS, ZnS, SnS, CdSe, barium titanate, lead oxide, tantalum oxide and tellurium oxide.