Metal finishing Q&As since 1989

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Powder coating gels up from contact with gasoline or brake cleaner

I had a custom bike frame and several other parts coated. 2 days later when we started assembly, some gas spilled out of the petcock and hit the 2 day old coating and it gelled instantly. also brake fluid gels it right up as well. We contacted the powder coater and he told us that wasn't possible but we tried it on another part and instantly it geled. he said it was our problem. What causes this and why, because when we confront him I would like to have a little knowledge so he can't blow more smoke up my butt. One color was orange and the other is black chrome. thanks, Jeff

Jeff Craven
custom paint shop owner - Lexington, North Carolina, USA
December 9, 2009

If the coating is attacked as you say "instantly" then it points to a problem of "under-cure" of the coating. This can be checked by using a coin to create a groove in the powder film near to the point of concern (this should not worry you as the item is already damaged). If the groove is smooth the powder film is cured and we have to look for another explanation. However, if the groove is jagged then this would indicate under-cure of the applied powder.

Terry Hickling
Birmingham, United Kingdom
December 10, 2009