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Zinc plating peels during powder coating heat treatment

Q. Manufacturing specifications for a component we are currently fabricating requires zinc plating and powder coating. Powder coating processes include preheating and post-process heat treatment at 350 °F. We are having problems with separation of the zinc plating from the base material during post-process heat treating. Need help.

Bruce Nichols
- Dallas, Texas
2003

"User's Guide to Powder Coating"
by Nicolas Liberto

on AbeBooks

or Amazon

(affil links)

A. More likely than not you are referring to the gold color separating from your parts after the baking process. Gold chromates can dehydrate with temperature.

Bill Grayson
- Santa Cruz, California
2003

A. Hi Bruce. Bill is surely correct that the zinc plating per se should have no difficulty adhering to the substrate, but the chromate can be problematic. The chromate must be thin and it must be allowed proper curing time, which is generally about 24 hours. Good luck.

Regards,

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

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