Anodizing of aluminum creates a thin, corrosion and wear resistant layer of aluminum oxide on the surface of the part. The layer will be scratch resistant, electrically insulation and increase corrosion protection.

The time in the etch batch can be varied to accomplish different surface finishes ranging from shiny to matte.

The anodized layer is grown on the aluminum in a sulfuric acid bath. The porous coating can be left clear or the porosity filled with a dye to color the coating. Following this process, the pores are sealed using a nickel containing seal.

Clear anodizing is typically done at a coating thickness of 0.6 to 1.2 mil. Since the anodizing process is consuming part of the base material to create the coating, the actual build-up is typically around 50%. So a 1.0 mil thick anodized coating will give about 0.5 mil of actual dimensional growth.