CLEAR OVER METALLIC
Q. I run a job shop with a batch system and we have powder coated different kinds of parts with many different kinds of powder.
I was recently asked to do a two-coat application with a clear powder over a silver metallic. We had never applied clear coat or done a two-coat process before, and the parts did not turn out well at all.
We applied the first coat and cured it, and it looked good. We applied the clear coat and then cured it, but it came out looking very cloudy. We had the parts stripped, but we are not sure how to redo them. What is the proper way to apply a clear coat over a color? H.G.
A. Start by applying the metallic and sending it into the oven for a partial cure instead of full cure. The powder needs to be “B” staged, a reference to partial cure to get flow and hardening without full cure.
Take the parts out of the oven, let them cool down to a temperature of around 110º or lower, and then apply the clear coat but be very careful to apply the proper thickness. It sounds like you put on too much clear coat before, and that is why the film wasn’t clear. Practice on some test panels to get your technique down.
After the clear coat is applied, put the part back in the oven for a full cure. You should get good results with this method.
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