Paste Forms of a Cold Chromate Etch Treatment for Aluminium

Abstract While the usual etching treatments in baths of solution are convenient and satisfactory for comparatively small components in conditions of factory manufacture, they are less adequate for large components and conditions which are less well controlled. To meet these conditions various modifications to produce etching treatments in a paste form have been explored. Many of these have involved the phosphoric acid anodising process but there have been reports of a paste formulation of the FPL chromic acid treatment although the details have not always been very precise.