Stainless Steel Mirrors: Does the film or coating on stainless steel mirror expire?

Stainless steel mirror’s film or coating cannot expire. Thanks to chromium’s (Cr) presence in steel’s alloy, the surface of a mirror is resistant to corrosion.

A stainless steel mirror’s surface has a coat, which has a thin layer called oxide film. This layer protects the mirror when there are climate changes, which makes oxidation reaction. Thanks to the oxide film, stainless steel mirrors can have high durability and weatherability.