Wet storage stain

Wet storage stain, more commonly known as white rust or white corrosion, is a type of zinc corrosion. It is called wet storage stain because it occurs when a fresh zinc surface is stored in a wet environment with limited oxygen and carbon dioxide sources; the restriction in air is usually due to the items being stacked on one another or otherwise stored in close quarters. This type of corrosion does not usually occur to zinc surfaces that have had time to form their normal layers of corrosion protection.