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topic 10781

Powder coating passivated galvanized

Faults in Hot-Dip Galvanizing

Phosphating of Metals
by Rausch


We manufacture several different types of cabinets and enclosures. Approximately 60% of these units are galvanized. Our success with powder painters has been sufficient to excellent. However, recently, problems have come up concerning the quality from one of our painters. He claims that passivated galvanized material is the cause of peeling/chipping problems with the paint.

This type of problem has not been a concern with our other painters for some time now and I suspect that this particular fellow is improperly prepping the material and/or improperly curing the material. As I am not a powder paint expert, any help with this problem and proper prep for passivated galvanized is greatly appreciated. I would simply like to know what is correct.

Thank you.

Curt A. Rouse
machine works - Saskatoon, Saskatchewan, Canada

June 1, 2009

Hi, Curt. I believe that you are right that there is a pretreatment issue. The best pretreatment for galvanized metal is zinc phosphating. This question has been asked frequently, so if you search the site you will find many similar threads, and I think you'll agree that zinc phosphate is the only way to go. Good luck.


Ted Mooney, Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

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