The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 23, 1991
Filed:
May. 23, 1990
Klaus-Dieter Bartkowski, Krefeld, DE;
Peter Venn, Wuppertal, DE;
Gebr. Happich GmbH, , DE;
Abstract
There is described a chemical method for the avoidance of a rainbow effect which is caused by the layer of oxide produced upon the brightening of parts of aluminum or aluminum alloys, in which the parts are degreased or cleaned in a first process step and then subjected to electrolytic-alkaline brightening in a second process step, the method being characterized by the fact that, after the brightening, the parts are subjected to a further treatment in which the parts are first of all washed in water and then exposed in a chromic-acid solution preferably containing about 50 grams per liter of CrO.sub.3 at about 98.degree. C. for about 3 minutes and finally washed again in a sodium hydrosulfite solution.