- How To Powder Coat - Powder Coating Process Training - Eastwood Tech Library
What is Powder Coating?
So you've heard of it, but, you're not quite sure exactly what powder coating is. According to the Powder Coating Institute, "Powder coating is an advanced method of applying a decorative and protective finish to a wide range of materials and products that are used by both industries and consumers. The powder used for the process is a mixture of finely ground particles of pigment and resin, which is sprayed onto a surface to be coated. The charged powder particles adhere to the electrically grounded surfaces until heated and fused into a smooth coating in a curing oven. The result is a uniform, durable, high-quality, and attractive finish." There, so now you know! Or do you?
Our HotCoat® Powder-Coating Guns, like most powder coating guns, apply a negative electrostatic charge to the flour-fine powder (that magical mixture of "pigment and resin"). This charge is high voltage; up to 25,000 volts (100,000 volts on industrial guns), but fortunately very low amperage (the amps are the part of electricity that can really hurt you). Since this powder is made of resins, we know that it falls in the general classification of "plastics". As a member of the plastic family, it is a poor conductor of electricity. So once the particle is charged, it gives up that charge very reluctantly. This is what causes the powder to "cling" to the substrate being coated. The negative ions in the particle slowly fight their way to the positively charged substrate. This slow flow of ions from particle to substrate is what holds the particle on the substrate. Putting it another way, think of the positively charged substrate as "sucking" the negative ions out of the particles, causing them to stick.
Why is Powder Coating Better?
Powder coating gives consumers, businesses, and industry one of the most economical, longest-lasting, and most 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. Thanks to the UV resistance of many of the powders, 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 VOCs into the atmosphere. Thus, there is no longer a need for finishers to buy costly pollution control equipment. In addition, most powder coating overspray that does not adhere to the part can be retrieved and reused. Although this is not always practical for many low-volume users, this can virtually eliminate the waste commonly found in liquid finishing processes.
Elimination of VOCs and reduction of wastes save money and help companies comply more easily and economically with the regulations of the U.S. Environmental Protection Agency. In fact, one of the major elements in expanding the market for powder coating has been the implementation of stringent air pollution control legislation over the past 30 years.
Where is Powder Coating Used?
The appliance industry benefits from powder coating on front and side panels of ranges and refrigerators, washer tops and lids, dryer drums, air-conditioner cabinets, water heaters, dishwasher racks, and cavities of microwave ovens. Powder coating has also replaced porcelain enamel on many washer and dryer parts.
The architectural and building market powder coats aluminum extrusions used on frames for windows and doors, and modular furniture. Many highway and building projects use powder coating on light poles, guard rails, signs, posts, and fencing.
Henry Ford once said, "You can have a Model-T in any color you want, so long as it's black." For an industry once focused primarily on manufacturers' needs, powder coating is transforming the automotive industry with faster production times and lower operating costs, plus irresistible value propositions for consumers. For years, conventional liquid coatings were the standard for the automotive industry. But these coatings can emit dangerous VOCs at their application stage. Powder coatings eliminate most environmental concerns and the need for costly waste disposal systems. Because powder does not run or drip, the result is a uniform, superior-quality finish.
Conversion from liquid to powder clearcoats for auto body exteriors is moving rapidly. Powder topcoats resist acid rain, the sun's ultraviolet rays, and road and weather damage, helping cars retain their "showroom look" much longer and improving their resale value. BMW and Volvo are using it on their new model cars, and GM, Ford, and Chrysler have formed a consortium to test this technique on their production lines.
Powder coating has made substantial inroads as a primer for car, van and pickup truck bodies in the United States. Auto body primers in colors will be next.
There is huge market potential for high-heat-resistant powder coatings on aftermarket mufflers, which resist corrosion, protect against nicks and prolong the life of the muffler. Some companies are already applying heat-resistant powder to aftermarket mufflers, and the new-car market is thought to be two or three years away.
Powder coating is also applied to wheels, grilles, bumpers, door handles, roof racks and exterior and interior trim. "Under the hood" uses include oil and fuel filters, brake pads, engine block casings, suspension components and radiators. Pickup truck and SUV owners can purchase powder-coated side steps, bed rails, luggage racks and toolboxes as dealership add-ons or in aftermarket stores and catalogs.
Performance car owners can find powder-coated special suspension units, carburetor parts and valve covers, plus flashy rear-view mirror mounts and other exterior adornments.
There are also innumerable everyday uses for powder-coated products such as lighting fixtures, antennas, and electrical components. Farmers have powder-coated tractors and farm equipment. Fitness buffs use golf clubs and golf carts, ski poles and bindings, snowmobiles, bicycles, and exercise equipment that are powder-coated. Shop owners have powder-coated display racks, shelves, store fixtures, and vending machines. Office workers use metal furniture, computer cabinets, mechanical pencils and pens, thumbtacks, and other desk accessories that are powder-coated. Parents have powder-coated baby strollers, cribs, metal toys, and wagons. And home owners have lawn mowers, snow blowers, barbecue grills, patio furniture, garden tools, electronic components, bathroom scales, tool boxes, and fire extinguishers which benefit from a powder-coated finish. The powder-coating boom has just begun -- expect more exciting uses in the near future.