Does aluminum rust?

Technically, aluminum does not rust. However, a layer of oxide forms over the metal to protect it against further corrosion. This layer bonds strongly to the metal, is self-repairing if damaged and holds up well under conditions that are strongly acidic or strongly alkaline.

When iron corrodes and forms rust, the rust flakes off easily. This leaves the metal vulnerable to even more rust. Eventually, the iron deteriorates altogether. The layer of oxide is one of the properties that makes aluminum a sought-after product in construction, especially in aluminum siding. Aluminum is also used for cookware, packaging, and car and boat parts.