Anodizing is an electrochemical process that converts the aluminum surface into an oxide layer (Al₂O₃). The coating forms directly from the metal and becomes an integral part of it— this is why it does not peel or flake off. An important engineering consideration: anodizing does not hide surface defects of the profile — it actually makes them more visible. Stains, streaks, and press marks become more noticeable after anodizing.