Letter 12306

Bubbling Issue with Powder Coat on Zinc Plate with Yellow Chromate 

We zinc plate .001" then yellow chromate a part for powder coating. The plate adhesion is good. However the powder coating supplier is having a bubbling problem. The bubbling is only the powder coat not the plate. Can the chromate cause a problem to the powder coater? The powder coater is concerned with the plate thickness in threaded areas as being the problem. Is there a minimum thickness required for zinc plate before powder coat?

Thanks,

Carol Shibles
- No. Andover, MA, USA

Generally the chromates if properly applied over clean surfaces will provide excellent adhesion and no bubbling. Without actually putting the parts through a battery of tests myself, the only thing I can add is that a high percent of the failures that I have seen were caused by impurities in the plating, not the chromate. I also have found that you can usually see if the plating is bad if you see cloudlyness or uneven coloring on the surface.

Just a shot to look at...good luck.

Bob Utech - Brooklyn Park, MN

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