White rust is a white, chalky substance that can form on the surface of zinc materials, like #galvanized steel. It forms when zinc is exposed to hydrogen and oxygen. This combination creates a zinc hydroxide, as opposed to the iron oxide which is common form of rust.
Where can White Rust Form?
While it can form on any zinc material or zinc-coated material, white rust is a frequent problem for galvanized steel. How Does it Form? It forms when zinc is in an environment with hydrogen and oxygen. Most frequently, it occurs when a freshly galvanized material is placed into contact with water, or hydrogen dioxide.
White rust is highly likely to form on newly galvanized material as opposed to older coils that are stored properly. This is because the new zinc coating has not yet had the chance to form the stable oxides, and the hydrogen and the oxygen bond with the pure zinc which forms zinc hydroxide. White rust can be common on galvanized sheet that is being stored, as condensation can become trapped between the individual sheets, leading to the formation of white rust. Surplus Metals are buyers of these coils and sheets.
This defect is not a deal breaker!
Just because coils have defects does not mean that we wont buy them. Surplus Metals is a daily buyer of a wide array of coils. We are happy to help sell steel with defects. There is no reason to scrap coils like this. There are tons of non-surface critical applications for white rusted galvanized that will never see the light of day and we have those jobs available.
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Metal Supermarkets does a great job laying out White Rust in this article.