What is Powder Coating?
Powder is a dry form of paint applied by electrically charging the powder and grounding the part. Most powders start out as a liquid, very similar to spray paint. The resin, various components and pigments are mixed into a homogenous solution. They are then partially cured, converted into a solid, extruded and ground to the desired particle size.
There is a misconception out there that powder is some space age material similar to high tech ceramics and carbon fiber. Powder is just another method of laying down an organic film such as paint. A coating of epoxy powder will have the same basic properties such as poor UV resistance as a liquid paint. Most powders have very good chemical and corrosion resistance, but again it is resin specific. Epoxies have excellent chemical resistance. Polyesters and Urethanes are typically used for aesthetic coatings and have good resistance. One big advantage that powder has over liquid paint is its curing or drying of the coating. As a liquid coating dries, solvent (VOC’s) has to escape from within the film as it cures. While the solvent is evaporating it is leaving small pin holes in the surfaces. This creates an area for moisture and chemicals to penetrate the film and cause corrosion. Powder simply melts at the cure temperature and is not prone to pin holing. Typical powder cure cycles are 350-400°F @ 15-25 minutes.
Environmental and Advantage Issues
Powder coating is very environmentally friendly. Powders contain no solvents and thus have very low air emissions when curing. Typical powders have a VOC (Volatile Organic Compound) rating of <1.0 pounds per gallon versus liquid paints in the range of 2.5-7.0 pounds per gallon. There is very little waste with powder. The dry powder used in powder coating has the look and feel of talcum powder. It is also just as safe because it contains none of the VOC’s typically found in liquid paint.
Powder coating is easier to apply than liquid painting. Clean up is also simpler, you can use an air hose or vacuum instead of harmful solvent.
What Are Its Advantages?
Powder coating gives consumers, businesses, and industry one of the most economical, longest-lasting, and color-durable quality finishes available.
Powder coated surfaces are more resistant to chipping, scratching, fading, and wearing than other finishes. Color selection is virtually unlimited with high and low gloss, metallic, and clear finishes available. And colors stay bright and vibrant longer. Texture selections range from smooth surfaces to a wrinkled or matte finish, and rough textures designed for hiding surface imperfections.
Protects the Environment
Powder coating is also highly protective of our environment. While liquid finishes contain solvents which have pollutants known as volatile organic compounds (VOCs), powder coating contains no solvents and releases negligible amounts, if any, of VOC’s into the atmosphere. Thus, there is no longer a need for finishers to buy costly pollution control equipment. In addition, most powder coating over spray that does not adhere to the part can be retrieved and reused, virtually eliminating the waste commonly found in liquid finishing processes.