Custom aluminum
anodizing.

What is anodizing

Anodizing is an electrochemical process in which an oxide layer grows on the aluminum surface. It is not a coating or paint — the layer forms through conversion of the material itself, so it does not peel off.

The resulting layer is harder than the base material, protects against corrosion, and is electrically non-conductive. Standard thicknesses range in single-digit micrometers; with hard anodizing, in tens — in which case the layer significantly increases wear resistance.

The surface can be colored. Black and natural silver are most common; other shades are also possible. The final shade depends on the alloy, so parts from different batches or materials may vary slightly — for visible assemblies, this is addressed through joint anodizing.

The layer grows partially into the material and partially outward, causing a slight dimensional change. For tight fits and threads, it is therefore advisable to indicate in the drawing whether the dimension is before or after treatment.

Only aluminum and its alloys can be anodized. For steel, blackening or galvanizing serves a similar function.