Agfa Gevaert Nv

Antoine A De Jaeger

Albert Lucien Poot

Rene M De Keyzer

Francis J Sels

Gina C De Lamper

Alfons J Bertels

Albert P Wagemans

A method for the preparation of a planographic printing plate wherein a sheet material, which comprises an exterior hydrophilic colloid layer having concentrated on its surface a silver image formed by the silver complex diffusion transfer process with NiS or mixed crystal NiS.Ag.sub.2 S development nuclei in which the molar ratio of NiS to Ag.sub.2 S is not smaller than 1:1, is treated with a liquid for hydrophobizing the silver image for planographic printing, such liquid containing in dissolved state a heterocyclic compound corresponding to one of the following tautomeric structures (A) and (B) or (C) and (D): ##STR1## wherein: R.sup.1 represents hydrogen, amino or acylamino,

Method for the preparation of a planographic printing plate using NiS

Process for the production of a planographic printing plate by means of the silver complex diffusion transfer reversal process comprising the steps of:

Production of a planographic printing plate through the silver complex

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Wilrijk, Belgium

Antoine A De Jaeger