Electrolytically treating aluminium surface in bath of hydroxide or salt with acid

Abstract From the Canadian patent

Abstract of the Disclosure, An article of aluminum or aluminum alloy is electrolyzed in an electrolytic bath composed of an aqueous solution containing at least one hydroxide or salt of an alkali or alkaline earth metal or further including at least one substance capable of forming barrier-type layer selected from inorganic acids organic, acids and ammonium salts of weak acids by applying an, alternating current between the electrodes and allowing, bubbles formed during the resulting electrolysis to flow across the surface to form a grain-like or wooden like pattern on the surface. The thus obtained grain-like pattern may be directly subjected to usual coloration treatments or may be …