Smudge Removing

Smudge or stain or mark Removing

During the degreasing of aluminum alloys, a dark smear consisting of the products of solution of the alloying constituents is formed on their surface. To remove this smudge film or markin on the aluminum surface, the parts are treated in a solution containing 100 kg. chromic acid, 18.4 kg. 98 percent sulfuric acid and 1 Klt water. This solution is used at 15-25 oC and the time of treatment is 2-5 minutes. The smudge can also be removed in a 30 - 55 percent solution of nitric acid. After the removal of smudge, the parts are washed with water and are then ready for anodizing.