What is a common indicator of corrosion on metal surfaces?

Pitting or uneven surface is a well-recognized indicator of corrosion on metal surfaces. Corrosion often manifests as localized deterioration, which leads to the formation of small holes or pits in the metal. This occurs due to electrochemical reactions that can take place in moist environments, particularly where metals are exposed to salts or other corrosive elements.

When corrosion starts to affect a metal surface, it breaks down the material at specific points rather than uniformly across the surface, resulting in a distinctive pitting effect. Such uneven surfaces signal that the integrity of the metal has been compromised, indicating a need for inspection and potentially more protective measures to prevent further damage.

On the other hand, a bright shine generally denotes a well-maintained or polished surface, not one that is corroding. A uniform texture suggests that the metal is intact and not suffering from corrosion. An increase in weight is not a typical sign of corrosion; in fact, corrosion usually leads to a reduction in weight as material is lost. Thus, the presence of pitting or uneven surface characteristics serves as a clear and practical indicator of metal corrosion.