Patent ID: 7413844

Claim:
A method of manufacturing a lithographic printing plate support comprising a surface which has: an arithmetic mean roughness R a of 0.40 to 0.50 μm; not more than 1.5 recesses with a depth of at least 4 μm per 400 μm square region; and a surface area ratio ΔS 5(0.02-0.2) defined by formula (1): ΔS 5(0.02-0.2) (%)=[( S x 5(0.02-0.2) −S 0 )/ S 0 ]×100(%) (1) wherein S x 5(0.02-0.2) is the actual surface area of a 5 μm square surface region as determined by three-point approximation based on data obtained by extracting 0.02 to 0.2 μm wavelength components from three-dimensional data on the surface region measured with an atomic force microscope at 512×512 points and S 0 is the geometrically measured surface area of the surface region, of 70 to 82%, said method comprising: subjecting an aluminum plate at least to a first electrochemical graining treatment in a nitric acid-containing aqueous solution and a second electrochemical graining treatment in a hydrochloric acid-containing aqueous solution; and bringing the aluminum plate having undergone the first and second electrochemical graining treatments into contact with an alkaline aqueous solution to carry out alkaline etching treatment until the amount of a material removed by the alkaline etching treatment reaches 0.01 to 0.08 g/m 2 .