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Powder Coating Technical

Get More Gloss From Powder Coated Parts

Powder coating is an undeniably tough and long-lasting finish for so many applications. But even though it lays out smooth when applied properly, the nature of the material can leave a shiny, but not super-glossy, final finish. One of the questions that comes up often is how to enhance the gloss on powder-painted parts.

To get some straight answers, we turned directly to an expert on powder coatings, Mark Robidoux. Mark is Eastwood’s product development manager and was instrumental in bringing DIY powder coating to the market. He’s experimented with all types of powders and base materials over the years and knows what works and what doesn’t.

The important thing to understand is that powder paint behaves considerably differently than liquid paints. Typically, you apply the powder to your part, let it bake and cure, and you’re done. No cutting, buffing, or polishing is usually required or even recommended.

But what if you’re still not happy with the gloss? Here’s what he recommends to bring up the shine.

Powder coated valve cover
Even candy colors can be enhanced

Apply clear powder

If gloss and depth are priorities for your project, the first recommendation is to make sure you’re spraying clear powder on top of your color coat. “I recommend customers do a second coat of gloss clear, which is acrylic and great with UV, chemicals, and clarity,” he explains. “You can either spray at room temperature or hot flock it.” In this case, hot flocking involves spraying clear powder on a part while it is still warm from its initial application. The powder can begin to flow out on contact and the go back into the oven to cure.

But Mark advises caution when hot flocking clear finishes. “I tell customers if hot flocking to get in and get out. By this I mean adjust the gun to get a nice powder cloud, pull the part from oven and spray quickly, watching the clear powder hit the surface and flow out. Then get the part back in the oven quickly to keep it at temp and cure at 400° F for another ten minutes.”

Use a powder polish

To get more shine out of a cured part, or to remove slight blemishes from the surface, use a powder-specific polish. Eastwood developed a powder coating polish that can be applied either manually or with a buffer/polisher. For best results, this should only be used on non-metallic gloss finishes applied to smooth surfaces.

Hand application is recommended for light scratches and translucent powders to avoid burn-through. However, it can also be applied using a soft foam pad on a machine buffer at low to medium speeds. The key is to keep the foam pad moist and to prevent heat buildup, which could cause the finish to soften and potentially re-flow in spots.

Once polished, a powder coated finish can also be waxed to further enhance depth and gloss, if only temporarily.

Powder coated valve cover
Original finish (above/left) and after machine polishing with soft foam pad (lower/right)

Cut and buff only when necessary

If all else fails and you want a more flawless finish, you can bust out the fine-grit sandpaper and go to town. This might be necessary for correcting runs or rough spots in the finish, for instance. But Mark cautions, “You can cut and buff non-metallic powders, but if the substrate isn’t level to begin with (cast brake drum, for example) it will be hard.” In other words, the finish can only look as good as the part you’re applying it to.

As he further explains, “You could cut cured powder from 1000-grit to 3000-grit and buff it for more gloss, but it’s a lot of work. Powder doesn’t harden like a 2K urethane topcoat, so cutting or sanding requires more effort and finesse not to leave heavy sanding scratches in the finish.” After using abrasives, always finish with a powder polish.

Powder coated valve cover
From left to right, this section has been sanded with 1000-grit, 1500-grit, 2000-grit and 3000-grit paper and them machine polished

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