Peeling Powder

Ask an Expert From: Products Finishing, , from Powder Coating Consultants, Div. of Ninan, Inc.

Posted on: 2/1/2004

Question: We found powder peeling off parts.

Question:

We found powder peeling off parts. After talking to the shop supervisor he informed me that he had to put a second application of powder on some parts. We are using polyester, could you tell us the best way to recoat over powder? D. A

Answer:

To maximize intercoat adhesion on a two-coat powder coating several steps should be taken:

First, ensure that there are no additives in the powder that can be an impediment to adhesion (i.e. slip additives, gloss reducers, etc.). Some powder formulations cannot be re-coated without severe adhesion failure.

Second, scuff sand the surface between coats for a good bond. Be careful to remove any sanding dust.

Third, do not allow the powder coated part to be pretreated by the washer a second time, as this will cause spotting and other problems. Rinsing with fresh water is perfectly acceptable.

Lastly, ensure that both coats are fully cured.

 

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