Wearing away due to oxidation-reduction , oxide ).
It occurs whenever a gas or liquid chemically attacks an exposed surface, often a metal, and is accelerated by warm temperatures and by acids and salts . Normally, corrosion products (e.g., rust, patina) stay on the surface and protect it. Removing these deposits reexposes the surface, and corrosion continues. Some materials resist corrosion naturally; others can be treated to protect them (e.g., by coating, painting, {{link=galvanizing">galvanizing , or anodizing ).