Powder coating is usually applied onto various metal products to provide protection against the elements and for decorative purposes as well. Unlike with liquid paints used in paint preparation—which require the use of a solvent to dissolve different components, such as the binder, flow modifiers and the pigment—powder coating involves the use of various powders, which are applied electrostatically and oven-baked, so they can cure under heat. Generally speaking, powder coated products tend to last much longer than painted ones.
If you are a metal fabricator, it is important to know about the various types of powders available out there that can be applied on metal products before making a choice. Here is a look at some common types of powders that can be used for metal coating applications.
Epoxy powders provide a hard, durable finish that has a smooth, uniform appearance. They also provide excellent adhesion and a strong resistance to chemical reactions. Epoxy powder coatings are electrically insulative, thanks to their good electrostatic charging qualities. On the downside, however, epoxies cannot withstand constant exposure to UV light. They form a whitish haze (chalking) when over-exposed to UV light, making the items look unsightly.
These powders are mostly used when clear coats are needed. Acrylics also provide a hard, chip-resistant, smooth finish with excellent chemical resistance. Unlike epoxy-based coatings, acrylics do well when exposed to the sun's UV rays, retaining their high gloss finish. The major concern with acrylic powders is their brittleness and thus lack of durability. Currently, acrylic powders are commonly used in the automotive industry to create a clear coat on materials.
Polyester coatings wear down well and keep looking great longer than epoxy coatings. They offer excellent resistance to abrasions. Like acrylics, they hold up against UV light exposure pretty well; hence they are favoured for outdoor applications, such as exposed car parts and outdoor furniture. Some polyester coatings are used for building exteriors because of their ability to maintain their initial colours for several years with only minor fading while still offering maximum protection against the elements.
As the name clearly suggests, these powders are a hybrid of epoxy and polyester powders. Combining polyesters and epoxies creates a longer lasting coating that is less prone to chipping or cracking. While this type of coating offers superior heat stability over epoxy coatings, it cannot match the exterior durability associated with polyester coatings.