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White Rust

What are the possible causes of white rust versus red rust on phosphated and oiled parts?

Sue Sestina
- Jackson, Michigan, USA
2003

White rust is the corrosion product of zinc. It can be cause by the presence of an electrolyte such as water in the oil or too thin of an oil coating leaving porosity where corrosion can take place. The most likely cause is porosity in the basis metal that traps cleaner, phosphating solution or rinse water. The white corrosion can take place under the oil. red rust will soon follow.

Don Baudrand
Consultant - Poulsbo, Washington
(Don is co-author of "Plating on Plastics" [on Amazon or AbeBooks affil links]
and "Plating ABS Plastics" [on Amazon or eBay or AbeBooks affil links])
2003

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