BSA is a type of anodizing that results in a thin oxide layer with optimal adhesion properties and a good corrosion resistance. Like all types of anodizing, aluminum is converted into aluminum oxide, as a result of which optimal adhesion is guaranteed. BSA is applied if strict requirements are imposed on corrosion resistance and sulphuric anodizing is not an option due to the negative effects on the fatigue strength. The BSA-process is mainly applied to aerospace components. A large number of fine pores occur in the oxide layer during the treatment which are normally not sealed after anodizing, because most of the time BSA is used as a pre-treatment before paint application.