Anodising is basically a process-driven thickening of the protective oxide film that occurs naturally on the unprotected metal’s surface. It involves the conversion of base metal and thus is not a “coating” in the usual sense. The anodising process involves passing an electrical current through aluminium lying in a weak acid bath. This process forms the thickened protective film of aluminium oxide on the surface of the aluminium.
There is much science in balancing solution structure, characteristics of the metal being anodised, and the current required in achieving consistent high quality finish, and some art...
