Powder coating is a method by which items are coated in a durable, attractive finish. Unlike wet paint finishing methods, powder coating offers superior corrosion resistance and protection while being environmentally safe. The method by which powdered pigments and resins is applied is fairly straightforward, but there are several important tips powder coaters need to achieve optimal results. In this article, we will discuss preparation, equipment settings, and spraying techniques to help powder coated products look their very best.
Preparation is key in the powder coating process. Parts to be finished must be cleaned thoroughly of oils, dust, and debris – this is often achieved through media blasting and solvent dipping. Once the parts are cleaned and ready to spray, it is critical to keep them clean. Professional powder coating services use dedicated spray booths or clean rooms, both to keep parts clean and to eliminate overspray from getting into the work and preparation areas. Parts should be hung on a rack; be sure the rack and hooks are also clean. It can be helpful to spray yourself off with compressed air before entering the spray booth/clean room. This can eliminate contaminants and dust from ruining the finish.
Professional powder coating guns feature adjustments to help achieve the desired thickness and a smooth, even coat of powder. Powder guns typically have two settings to adjust: pressure and voltage. Powder coating uses low air pressures, typically in the 5psi to 10psi range. The lower the pressure, the better. In fact, for parts that have complex shapes and recessed areas, it is useful to set the gun at a low pressure that it is just enough for the powder to spray out of the equipment. Experienced powder coaters know that the compressor pressure is not the same as the pressure at the gun itself. To overcome pressure losses, an inline PSI gauge installed at the gun end of the hose can help powder coaters monitor the optimum pressure.
Voltage is another critical setting. Top-quality powder coating guns allow the operator to adjust voltage, measured in kilovolts or KV. The higher the KV setting, the more efficient the transfer of powder to the part being coated. However, there are exceptions: for large, uniform parts, high KV settings, such as 100KV, are beneficial. For more complex parts, lower KV settings, particularly in the 25-50KV range, can help the powder coater shoot an even coating over all surfaces of the part to be coated. Second coats always use less voltage; for second coats, dial the KV setting back to 20-30KV.
Many powder coating spray guns on the market have replaceable nozzles and additional settings. Getting the right coating thickness often takes experimentation with different gun settings.
For mirror-smooth coatings free of unsightly orange peel and overspray, correct spraying technique is called for. Professional powder coaters typically spray the flat areas first, then move to the more complex areas and recesses. Start the spray gun by pointing away from the item, then move toward the part to be coated. Just like in wet painting, a smooth arm motion from one side to the other helps achieve smooth, even coatings. Keep the spray gun six to eight inches away from the part, and try to coat the part in one smooth pass rather than erratic spraying at different angles and distances.
With these tips, it becomes easier to powder coat parts. Professional powder coaters, such as PowderCoat Services, Inc. have many years of experience in performing the steps necessary to achieve flawless finishes. With a little practice, a little experimentation, and these tips, you’ll be well on your way to powder coating like a pro!