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's web page,
"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® 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 we know that 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?
More Durable - 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 of
the low-volume users we service, this can virtually eliminate the waste commonly found in liquid finishing processes.
Money - Elimination of VOCs and reduction of wastes saves money and helps 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 over the past 30 years of stringent air pollution control legislation.
Is Powder Coating Used?
Appliances - 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
Architecture/Building - 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.
Automotive - 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
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.
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.
Everyday Products - 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, snowblowers, 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.
Information for this paper has been obtained from www.pci.org , www.pfonline.com and other sources.