Patent ID: 7348131

Claim:
A method of processing a lithographic printing plate comprising in order: (a) providing a lithographic printing plate comprising (i) an aluminum substrate; (ii) a photosensitive layer comprising a polymeric binder, a free radical polymerizable monomer, a free radical initiator, and a sensitizing dye; and (iii) a water soluble or dispersible overcoat; wherein said aluminum substrate is electrochemically grained, anodized, and further treated with a hydrophilic material, and has a reflection optical density of at least 0.30; said photosensitive layer is soluble or dispersible in ink and/or fountain solution and on-press developable with both ink and fountain solution; and said monomer has at least 3 (meth)acrylate groups, and the weight ratio of all the monomers having at least 3 (meth)acrylate groups to all the polymeric binders is larger than 1.0; (b) exposing said plate with a laser having a wavelength of from 200 to 1200 nm according to digital imaging information to cause hardening of the photosensitive layer in the exposed areas; (c) rinsing or applying said exposed plate with an aqueous solution to remove the water soluble or dispersible overcoat and to dampen without developing the plate; wherein said aqueous solution comprises a deactivating agent, and the rinse or application with said aqueous solution deactivates the photosensitive layer so that the non-hardened areas of said photosensitive layer become incapable of hardening under light during handling and on-press development; and (d) developing said exposed and deactivated plate with both ink and fountain solution on a lithographic press.