A PROCESS FOR ANODIZING AND INORGANIC BLACK COLOURING OF ALUMINIUM AND ITS ALLOY

摘要

This invention relates to a process for anodizing and black colour coating aluminium and its alloys. "rhe steps consist of degreasing. descaling. desmutting and then anodizing in a sulphuric acid bath. After anodization the article is immersed in a bath containing an aqueous bath of cobalt acetate and then irl an aqueous bath of yellow ammonium sulphide. These steps are repeated till the desired colour intensity is achieved. The article is then heated in a bailing bath of dimineralised water to seal the colour.