The production of an oxide layer on aluminium alloys. The process is electrolytic, a typical electrolyte being sulphuric acid. Treatment at room temperature produces thin, decorative layers with some corrosion protection. Treatment at 0oC produces hard, thicker layers (up to 100µ) with wear resistance. They can be post sealed to give improved corrosion resistance.

Anodising, or anodizing, is a technique used to coat the surface of a metal with an oxide layer. It may be used to increase corrosion resistance, increase wear resistance, allow dyeing or prepare the surface for other processes and coatings including paint. Anodization changes the microscopic texture of the surface and can change the crystal structure of the metal near the surface.