chemical process for preventing a regenbogeneffektes, by the shine of parts from aluminium or aluminium alloys resulting oxydschicht will cause.

摘要

A description is given of a chemical process for avoiding a rainbow effect provoked by the oxide layer produced during the polishing of aluminium or aluminium-alloy parts. In the process, the parts are degreased or cleaned in a first process step and given an electrolytic alkaline polish in a second process step. The process is distinguished by the fact that, after polishing, the pieces are subjected to a further treatment in which they are first rinsed in water, then exposed to a chromic acid solution containing about 50 g/l of CrO3 at about 98 DEG C for about three minutes, and finally rinsed in a sodium hydrogensulphite solution.