Powder Coated Steel Parts

Q. We have a problem with powder coated steel parts that have yellowed after a few months when exposed to high intensity UV from fluorescent lamps. The powder coating was an epoxy-polyester hybrid. What if anything can we apply over this to restore the original white color finish? Is Krylon spray an alternative? Thanks for any advice in advance. B. B.

A. Well, it looks like you selected the wrong powder coating for your product. Hybrid powder coatings have slightly better UV resistance when compared to pure epoxy. However, what you really needed to use was a polyester urethane, TGIC polyester, or acrylic powder coating, which are all formulated as highly UV resistant. As a rule of thumb these UV resistant powder coatings have 100+ times the UV resistance of epoxy or hybrids.

Now you have several choices. You can sand these parts to roughen the surface and recoat them using the right powder coating. You can try to apply an air-dried liquid paint over the powder coating, but you should still sand the surface first for better adhesion. If you select this alternative, be sure that you select a powder coating that has good UV resistance. You question about Krylon being suitable for this recoating has me stumped. I don’t know what the formulation properties of Krylon are, but I suspect it probably has at least fair UV resistance since many people use it to coat products used outdoors. Contact the Krylon Company for a better perspective.