Metal finishing Q&As since 1989

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Oxidation

2004

I work in maintenance at the zoo here in Waco, we are undergoing a major building project to double the size of our zoo, today I noticed a roof they were putting on one of the buildings, they already had half of it roofed several months back, the remaining roofing material [corrugated iron]has been stored uncovered out in the weather for about the last 3-6 months, I noticed today that it is almost white with oxidation, my question is will this speed up the rust process which sometimes happens with this type roofing? I want to bring this up to the Zoo director but want to know all the facts before doing so.

Thanks,

Richard Wilshire
Maintenance - Waco, Texas, United States

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2004

The roof panels with white corrosion may not be totally unacceptable to install, but they are definitely an issue that needs to be discussed rather than ignored. This problem seems to occur when galvanized materials are wet and have limited ability to breathe--such as when left in a stack outside, as opposed to being individually mounted on a roof. Some people call the problem "wet storage stain".

If you search our site with terms like "white rust galvanize" and "wet storage stain" you will find numerous discussions of this problem. I'd suggest you start with letters no. 09, 720, and 8523.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey