Lithographic printing press and method for on-press imaging laser sensitive lithographic plate

A method of lithographically printing images on a receiving medium, comprising in order:

• (a) providing a lithographic printing press comprising (i) a plate cylinder, (ii) an exposure means capable of emitting a laser having a wavelength selected from 200 to 1200 nm, and (iii) an inking means comprising an inking unit and a fountain unit;
• (b) mounting from a light-tight cassette onto said plate cylinder a lithographic printing plate comprising on a hydrophilic substrate an oleophilic photosensitive layer soluble or dispersible in ink and/or fountain solution and capable of hardening upon exposure to said laser;
• (c) imagewise exposing said plate with said laser to cause hardening of the photosensitive layer in the exposed areas;
• (d) applying ink and fountain solution from said inking means to said plate to remove the non-hardened areas of said photosensitive layer;
• and
• (e) lithographically printing images from said plate to the receiving medium;
• (f) wherein said press is in a pressroom having white room light;
• and at least said plate mounted on the plate cylinder is within a compartment shielded with covers and other press parts so that, when the covers are fully closed, the intensity of the light at each wavelength below 450 nm around the plate cylinder is less than 1% of the intensity of the room light around the outer top surface of the press at such wavelength;
• and said covers are fully closed during substantially all of said steps (b) to (d) and are at least partially opened during substantially all of said step (e).