White Rust

The white swirls are from the zinc reacting with the atmosphere around it to form zinc hydroxide. This is commonly known as white rust. It is the first step to the coating stabilising. White rust gets worse if there is inadequate venting. With adequate venting the white rust reacts further with carbon dioxide to form a dull grey Patina (layer) on the outside of the coating. This is anither layer of protection to combat corrosion and is the reason why almost all galvanizing fades to the same dull grey colour over time. Excessive white rust is not acceptable and repair or re-dip may be required.

white, powder, light

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