Patent ID: 7571542

Claim:
A method of manufacturing supports for lithographic printing plates, comprising: subjecting a surface of a steel roll to at least the steps of, in order: blasting treatment, electrolytic treatment with 1,000 to 20,000 C/dm 2 of electricity in which the steel roll is used as the anode, and chromium plating treatment, such that the surface of the roll has a maximum height Ry of 5 to 25 μm, and an average slope Δa of 5 to 25°; and transferring recessed portions and protruded portions to a surface of an aluminum sheet with the roll, wherein the roll prior to the electrolytic treatment has a mean surface roughness Ra of 0.3 to 1.5 μm, and the roll after the electrolytic treatment has a mean surface roughness Ra of 0.5 to 2.0 μm and a mean spacing for profile irregularities Sm of 10 to 200 μm.