Nonchromic Acid Brightener for Brass and Copper

A process for precleaning brass and copper parts before processing them further in a clean room includes a brightening chemical treatment in solution of 85 volume percent phosphoric acid, 3 volume percent nitric acid, and 12 volume percent acetic acid. This solution acts rapidly and can be discarded easily; it replaces a chromic-acid brightening solution that has become subject to environmental regulation. In preparation for the treatment, a part is first alkaline cleaned, rinsed with water, and dried until no water is visible. The part is then treated by immersing it in the solution for 10 seconds or until bubbles appear on all its surfaces. The part is then rinsed with water and dried.