Treating developed lithoplate with oleophilic composition

Claim 1

A method of processing a radiation sensitive plate comprising a substrate coated with a layer of a positive-working radiation sensitive material comprising a novolak resin sensitized with a diazonium salt or a quinone diazide, which method comprises: (i) image-wise exposing the layer to actinic radiation using a continuous tone original in the absence of a half-tone screen, (ii) developing the image-wise exposed layer to selectively remove the radiation-struck portions of the layer and reveal the substrate underlying these portions and desensitising the revealed substrate to render the same oleophobic, (iii) drying the developed and desensitised plate, (iv) coating the dried plate with a liquid composition comprising (a) an oleophilic film-forming material which is a liquid hydrocarbon solution of a normally solid material selected from the group consisting of solid hydrocarbons, solid fats, and mixtures thereof, wherein the liquid hydrocarbon constitutes from 60% to 95% by weight of the composition, and the normally solid material constitutes from 0.5 to 5% by weight of the composition, and (b) an organic solvent liquid constituting from 0.1 to 30% by weight of the composition which is capable of softening the surface of the non-radiation-struck portions, (v) drying the coated plate to form an oleophilic layer on the non-radiation-struck portions and on said revealed substrate, and (vi) washing the plate to remove the oleophilic layer from said revealed substrate.

Claim 2

A method of processing a radiation sensitive plate comprising a substrate coated with a layer of a positive-working radiation sensitive material comprising a novolak resin sensitized with a diazonium salt or a quinone diazide, which method comprises: (i) image-wise exposing the layer to actinic radiation using a continuous tone original in the absence of a half-tone screen, (ii) developing the image-wise exposed layer to selectively remove the radiation-struck portions of the layer and reveal the substrate underlying these portions and desensitising the revealed substrate to render the same oleophobic, (iii) drying the developed and desensitised plate, (iv) coating the dried plate with a liquid composition comprising (a) an oleophilic film-forming material which is a liquid hydrocarbon solution of a normally solid material selected from the group consisting of solid hydrocarbons, solid fats, and mixtures thereof, wherein the liquid hydrocarbon constitutes from 60% to 95% by weight of the composition, and the normally solid material constitutes from 0.5 to 5% by weight of the composition, and (b) an organic solvent liquid constituting from 0.1 to 30% by weight of the composition which is capable of softening the surface of the non-radiation-struck portions, (v) drying the coated plate to form an oleophilic layer on the non-radiation-struck portions and on said revealed substrate, and (vi) washing the plate to remove the oleophilic layer from said revealed substrate.