We talk about powder coating in monolithic terms, but the truth is that “powder” can mean a lot of different things on the chemical level. And different powders serve different purposes.
Even though powder chemistry has a significant effect on the coating’s durability, one of our sales reps was telling me the other day that a lot of powder coating shops don’t necessarily know what they’re applying to parts, much less why. Spraying a part with powder that’s left over from a different project, just because that’s what’s on hand, may not result in customer satisfaction over the long term.
Different applications require different chemistries.
Of all the powder chemistries available on the market (and there are a lot), I want to focus on the three main categories: epoxy, polyester, and hybrid powders.
Epoxy is great for chemical resistance, but does not hold up well against UV light. When exposed to the sun, this epoxy coatings will chalk and fade in as little as two weeks. This makes it a powder for indoor application, particularly since it hold up well against cleaning products. More often than not, when we’re spraying epoxy powder, it’s as a primer – it creates a hard barrier between the part and any chemicals it might encounter, and is a strong base over which we can easily spray a polyester top coat.
Polyester powder is the poster child of the powder coating industry. When you picture a glossy, colorful top coat, it’s likely to be polyester. That’s primarily due to its versatility – far more resistant to UV light than epoxy powder, polyester powder comes in “regular” and “super durable,” which hold up well against direct sunlight for a year to five years, respectively. This makes super durable polyester powder ideal for indoor and outdoor application. When cured, this powder is also more flexible than epoxy, which tends to be rigid.
Polyester and epoxy powders can be mixed to create a hybrid formula for indoor application. Used for shelving, light fixtures, and office furniture, this hybrid hold up well against cleaners, but should not be exposed to too much UV light.
This is why, when you bring us a part, we’re likely to ask some questions about its purpose: will it be indoors or outdoors? Will it be exposed to cleaners and other chemicals? What are you looking for in terms of gloss and color retention? All of this will directly impact the powder chemistry we recommend.