TREATING ALUMINIUM WORKPIECES

摘要

PURPOSE: A method for improving a sheet is provided to alternate current anodize at a current density of at least 2 kAm-2 while anodizing in an aggressive electrolyte. CONSTITUTION: Surface defects on rolled aluminium alloy sheet, particularly that intended for use as lithographic plate substrate, are caused by copper-containing particles. The invention provides a method of improving the sheet by removing the particles by anodizing in an aggressive electrolyte, particularly alternate current anodizing at a current density of at least 2 kAm-2.