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What is Powder Coating?
Powder coating is the process in which electrically charged paint resin particles are sprayed onto a metal, wood or plastic surface and then fused to that surface with heat using a curing oven. Coating powders come in two grades, thermoplastic and thermosetting. Thermoplastic powders, sometimes referred to as "lacquers," are most often used for functional purposes. Thermosetting powders, often called "enamels," are typically used for decorative purposes.
Liquid Coating vs. Powder Coating
Powder coating has several advantages over the liquid coating process. Unlike liquid coatings, there is no need for premixing, stirring or thinning formulations. There is no need to constantly monitor and maintain the proper viscosity balance in powder coating, nor is the use of solvents required. Each paint particle contains the complete coating formulation of resins, pigments, and fillers for consistent and uniform coverage without sags or drips.
Powder coating is ecologically safe, with essentially nil emissions (nearly 99% of airborne particles are recaptured in the powder booth's cartridge and HEPA filters), and low levels of toxicity and flammability. Powder coating requires only one application, thus reducing shop/factory production time.
Being electrically charged, powder coating adheres to itself and will not flake, chip or peel off like a liquid coating. This means powder coated objects such as automotive parts can be machined or processed after coating.
Powder coating offers a wide variety of colors and finishes. Nearly all resins used in wet coatings can be used in powder coatings as well, with epoxies, acrylics, polyesters and polyurethanes used most often.
Powder Coating, Present and Future
Powder coating is the fastest-growing finishing technology in the United States, representing more than 10% of all industrial finishing applications. Powder coating technology has already displaced liquid-based coatings and its use continues to grow.*
The automotive industry employs the powder coating process both "under and over the hood." Under the hood, powder coatings cover oil filters, air filters, shock absorbers, coil springs, and other parts. Over the hood, clear powder topcoats give cars a "showroom finish" that resists acid rain and the sun's damaging ultraviolet rays.
In the building supply industry, powder coatings cover many products such as air conditioning units, porch columns, ceiling fixtures, window shutters, and door frames.
Recent innovations in powder coating system technology make it possible to apply the powder coating process to wood and plastic surfaces, even though they are not electrically charged. One technique focuses on applying powder coating to plastic surfaces at a lower curing oven temperature.
Anti-outgassing powder coat formulations reduce pinhole problems and improve the coating casting process.
Powder coating formulations are also being developed to withstand extreme heat, and are being used to coat heaters, exhaust systems, and gas grills.
Anti-microbial powder coatings have recently become available commercially. Anti-microbial agents such as silver are added to powder coating formulations and can eliminate most surface bacteria and germs.
* Source: Powder Coating Institute
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