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2nd tier powder coater sees outgasing on zinc plated parts

2003

I am starting to work for a company that paints metallic parts with powder (powder coating). One of my duties is following the process. Last week an outgassing defect was detected in at least 30% of production, the material coming from our supplier with plating (Zn) that we coat. The outgassing is detected after the oven. I would like to know the cause of this defect and how I can eliminate it--or at least where I can find articles , papers , manuals or books where I can learn about this.

Thanks for you time,

Miguel Segoviano
2nd tier automotive - San Juan del Rio, Quer´taro, Mexico

You may overcome your problem by using a anti-gassing powder. These are powders that have been modified and take longer to cure. This allows any gases in the substrate to pass through the film before final cure takes place. If this does not work use a waterborne primer - that will definitely stop it.

Terry Hickling
Birmingham, United Kingdom
2003

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Can you be specific about a water borne primer that is compatible with a powder topcoat? I have been dealing a lot with old porous iron and aluminum castings and have experimented with several things to stop the outgassing without acceptable results. It has been suggested that dipping the part after heating to above flow-out temp in a fluidized bed will overcome the problem as the part only has to be cured rather than the temperature being raised significantly after spray powder application. Any suggestions would be appreciated.

Larry Johnson
- Key West, Florida
2003