Agfa Gevaert Nv

Franciscus Heugebaert

Johan August Loccufier

Jean-Marie O Dewanckele

Johan Hubert Van Hunsel

Gilbert Voortmans

The present invention provides a method for lithographic printing comprising the following steps: preparing a lithographic printing plate according to the silver salt diffusion transfer process by (1) image-wise exposing an imaging element comprising on a support a photosensitive layer comprising a silver halide emulsion and an image receiving layer containing physical development nuclei in water permeable relationship with said emulsion layer, (2) developing said imaging element in the presence of developing agent(s) and silver halide solvent(s) using an alkaline processing liquid and (3), if said emulsion layer is overlying said image receiving layer, removing the layers overlying said image receiving layer, mounting said lithographic printing plate to a lithographic printing press, and printing while supplying to said lithographic printing plate a dampening solution and a printing ink characterized in that the dampening solution as used on the printing plate contains less than 1.0 g/l of a transparent pigment with an average grain diameter of less than 0.1 .mu.m and at least 0.35 g/l of a clay incorporating an inorganic polyphosphate peptiser.

Dampening solution for printing with a lithographic printing plate and a

The present invention provides a conversion liquid for converting silver areas of a silver based printing plate into ink repellant areas while rendering background areas of said silver based printing plate ink accepting, said conversion liquid comprising a hydrophobizing compound capable of adsorbing to said hydrophilic background areas and a hydrophilizing compound capable of adsorbing to said silver areas and/or a bleaching compound capable of oxidizing the silver in said silver based printing plate.

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Mortsel, Belgium

Franciscus Heugebaert