A method for making an offset printing plate according to the silver salt diffusion transfer process

摘要

The present invention provides a method for making an offset printing plate according to the silver salt diffusion transfer process comprising the steps of: image-wise exposing an imaging element comprising in the order given on a hydrophilic surface of a support (i) an image receiving layer containing physical development nuclei and (ii) a photosensitive layer comprising a photosensitive silver halide emulsion said photosensitive layer being in water permeable relationship with said image receiving layer, applying an aqueous alkaline solution to the imaging element in the presence of (a) developing agent(s) and (a) silver halide solvent(s) to form a silver image in said image receiving layer, treating the imaging element to remove the layer(s) on top of the image receiving layer, thereby exposing the imaged surface of the support by uncovering said silver image formed in said image receiving layer, characterized in that said aqueous alkaline solution comprises less than 0.003 mole/l of inorganic bromide salts and thiosulphate salts in a range from 0.005 mole/l to 0.05 mole/l.