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More than any other factor, the Clean Air Act of 1970 propelled powder coating processes to the forefront as a method to reduce air pollution by eliminating VOCs. At the time, many major coating companies thought the Clean Air Act signaled an end of solvent-based processes. Prior to that time, the fluidized bed coating process was well established and the electrostatic powder spray process had started to gain acceptance, but powder coating, in general, had not received widespread attention or commercial acceptance.

Now powder coating, especially the electrostatic powder spray processes, is universally accepted and specified as the Best Available Control Technology (BACT) to reduce air pollution. While powder coatings have many advantages over other industrial finishing methods from both a process and performance standpoint, it is the ecological advantages of powder coatings that continue to drive their growth and acceptance.

Powder Coatings Contain No Solvents

• Negligible if any VOC emissions to the atmosphere.
• Compliance with more environmental regulations.
• Permits may not be required or are typically easier to obtain for new booth installations.
• Administrative costs of inspections, permits, sampling, testing, and record-keeping are significantly reduced.
• Coating booth exhaust air is returned to the coating room.
• Less oven air is exhausted to the outside.
• The process is inherently safer and cleaner than systems utilizing solvent-based paints.
• No special transportation, storage, or handling techniques are required, compared with solvent-based paints.

Reduces Waste & Present Few Hazards

• In most systems, powder coatings are collected and recycled.
• First-pass transfer efficiency is high compared with liquid paint.
• Practically all powder coatings today are free of heavy metals.
• Practically all powder coatings are not hazardous waste by definition of the Resources Conservation and Recovery Act (RCRA) regulations.
• Disposal methods for waste powder are the same as for non-hazardous industrial wastes, in most states.

Consistent Results

Powder coatings are supplied ready for immediate use without additional pre-mixing, stirring, solvent additions, or viscosity adjustments. Besides the obvious savings in labor, finish quality variations are minimized. Even before the days when regulation mandated the use of low-VOC coatings, liquid paint users encountered problems such as pigment setting, poor atomization due to high viscosity, or sagging due to over-reduction with solvent. With waterborne or high solids coatings, the goal of consistently applied finish quality frequently becomes even more difficult to achieve. With powder, the absence of extra mixing means less process variation and better control over finish quality.

Film Thickness

A major quality advantage with powder coated parts is the ability to achieve the optimum film thickness in a single pass without problems of drips, sags, or runs. The definition of what constitutes the optimum film thickness varies considerably with the design of the part as well as its intended end-use. Powder coatings currently are being applied in film thickness exceeding 15 mils (375 microns) for applications requiring high dielectric strength or especially good corrosion resistance.

At the other extreme, powder can also be applied in thin films of less than 1.0 mil (25 microns) for those applications where lower film build is advantageous. At this time, the major percentage of powder applications target film thickness in the range of 1.5 to 2.5 mils (38 to 63 microns).

Edge Coverage

Powders can be formulated to provide a wide range of melt viscosities and can be applied over a wide range of film thicknesses. Therefore, powder coating can provide better edge coverage protection than can be achieved in single-coat liquid coating applications.

Mechanical Properties

The general purpose powder coating formulations that are widely used have a long-established reputation for providing an excellent balance of mechanical properties such as impact resistance, hardness, and abrasion resistance. Films having an extra hardness, greater chemical resistance, improved exterior gloss retention, and superior flexibility are all attainable (although not, necessarily, simultaneously in a single formulation). A powder coating material can be formulated to match virtually any requirement that can be achieved by a liquid coating. However, some film property specifications, which are readily attainable with powder, are difficult or impossible to achieve with liquid paints.

Corrosion Resistance

The combination of proper metal pretreatment and powder coatings can provide outstanding corrosion resistance. Part of the reputation that powder has achieved for good corrosion resistance is related to powder’s ability to consistently deliver high film builds and good edge coverage. However, equally important are the facts that powders provide high crosslink density, good resistance, to hydrolysis, low moisture and oxygen transmission rates, and films free from traces of any residual solvents.

Advanced Durability

Recent research and testing have developed specially formulated polyester powders that provide even greater weatherability than achievable in previous years and showing greater success in long-term Florida exposure testing. TGIC-based powders are being used on outdoor stadium seating and other exterior applications that were previously susceptible to degradation from ultraviolet rays. Light poles, lawn furniture, shopping carts, and shelving often benefit from powder with polytetrafluoroethylene (Teflon) additives for increased resistance to abrasion.

Electroconductive & Electrodissipative

Makes of electronic components sometimes use electroconductive and electro dissipative powder coatings, which provide electrostatic discharge protection of the components, critical during the manufacture, testing, and transport of electronic goods. The most common colors for these special powders are black and charcoal, but lighter colors are also available.

Heat-Sensitive Substrates

In recent years, ongoing research and development have been devoted to formulating powders that can cure at lower temperatures, below 212ºF (100ºC), without compromising durability or quality. These powders can be used on temperature-sensitive materials as well as on massive parts that require enormous amounts of energy with other curing systems. More wood materials such as particleboard and fiberboard now can benefit from a powder coated finish. This technology has helped to penetrate markets for office furniture, kitchen cabinets, and ready-to-assemble furniture for homeowners.

In addition to successfully penetrating the medium density fiberboard (MDF) market, successful testing has occurred on hardwoods such as beech, oak, ash, and walnut. Research is also being conducted on countertops, wood molding and trim, laminated flooring, and particleboard.

Powder coating has proven to be an effective finishing choice for other heat-sensitive substrates such as plastic parts made of nylon and polycarbonate. In addition, assembled or partially assembled products such as appliances, electric motors, automotive radiators, shock absorbers, foam core doors, and other products that may have plastics, laminations, electrical wires, or rubber seals, can now also receive a powder coated finish. Heat-sensitive alloys such as magnesium can also be powder coating. A powder coating is used to color or frost glass products such as bottles or light bulbs.

Hygienic Powder Coatings

Antibacterial and antimicrobial powders can help prevent the spread of bacteria and germs on products in homes, hospitals, restaurants, and food processing plants. 

High-Temperature Resistant Powders

Silicone-based powder coatings are often used on products that are subjected to prolonged periods of high heat, up to 1,000ºF (540ºC), and hold their color, gloss, and adhesion. Some of these products include gas and charcoal grills, fireplace inserts, engine exhaust components, and lighting fixtures.

Thin-Film Powders

Powder manufacturers are developing more powders for use in thin-film applications that may range from 0.8 to 1.2 mils. These powders offer more with less – better powder penetration into recesses, more film thickness control, and more effective first-pass transfer efficiency, with darker colors most effective in hiding the substrate underneath.

UV-Curable Powders

Specially formulated powders can cure by ultraviolet (UV) radiation in a matter of seconds, which is one way to cure products with heat-sensitive substrates or components. Many wood products have enough moisture content to provide sufficient conductivity, and electrostatic attraction can be increased by pretreating and preheating the wood to promote adhesion.

Near-IR-Curable Powders

Other specially formulated powders can be cured in a matter of seconds through near-infrared (IR) technology, due to the extremely high heat-up rate. These powders can even work on some heat-sensitive materials because the irradiated energy is almost entirely absorbed by the powder coating layer.

Virtually Any Color or Gloss

The color variety is almost limitless these days, with many coating suppliers offering a pallet of off-the-shelf colors as well as custom color match services to better meet the needs of small-volume powder users. There are also tints to add highlight color to a substrate or base coat, such as a brass look over polished aluminum.

A range from flat to high gloss is generally available. Smooth, high gloss coatings can offer high distinctiveness of image, creating an illusion of depth or wet looks. Matte finishes can hide surface defects or imperfections such as spot-welds, nicks, and scratches on a variety of substrates.

Multi-Color

Hammertones or veins give antique or distressed looks created by a black base with metallic pigments of gold, silver, or copper contrasting against the black. This weathered look is popular in the furniture and display industries that demand a broad range of multi-color looks, including granite, confetti, rusty, and weathered appearances.

Clearcoats

Clear powders are often used as an external protective layer on many brass products such as doorknobs, hinges, railings, lamps, and plumbing fixtures. There are also powders available that can substitute for chrome and brass plating in certain applications, even matching the high gloss of chrome. Clearcoat primers and clearcoats over exterior basecoats are being used on select models of several automakers.

Fluorescent / Pearl-Like

Powder coated finishes can now offer an icy or fluorescent appearance or the lustrous look of a pearl that may appear to change color depending on the angle of observation. Bicycles, wheel rims, garden tools, light fixtures, and some glass products benefit from this look.

Photoluminescent powder coatings are able to absorb fluorescent, ultraviolet, or incandescent light, and gradually re-emit the light. These are often available in blue, yellow, and green, and are used for road signs, hazard warnings, and markings on trucks, buses, and police cars.

Metallics

Metallic coatings, using particles of aluminum, mica, copper, or brass, add sparkling highlights, which can reproduce the appearance of the base metal and add sparkle to the look of the product. Metallic bonding can physically bond metal flakes to the basecoat powder. A variety of metallic finishes have been formulated for indoor and outdoor furniture, exercise equipment, lawn and garden tools, and other products, that can resemble the look of gold, chrome, or brass.

Textures

Textured coatings are often used to hide substrate irregularities, which may show with a smooth finish, provide a non-slip surface, or hide fingerprints while giving a distinctive feel to a product. Appearances vary from the look of fine sandpaper, a pebbly texture, or a rougher look resembling alligator skin.

Wrinkles

Powder coating finishes with a wrinkled look exhibit excellent resistance to high wear and weatherability conditions on backyard tools, exercise equipment, and shop displays.

Automotive Industry

The automotive industry continues to use powder coating on an increasing number of automotive parts and products. Powder coating is used on oil and fuel filters, shock absorbers, battery trays, brake pads, engine block casings, suspension components, and radiators. Powder coating is also applied to wheels, grills, bumpers, door handles, roof racks, trailer hitches, and exterior and interior trim.

Clear powder topcoats and anti-chip coatings are now being applied to a number of automobiles and sport utility vehicles. These clear coats resist acid rain, the sun’s ultraviolet rays, and weather and road damage, helping cars retain their showroom look much longer and improving their resale value.

Powder coating has made substantial inroads as a primer for car, van and pickup truck bodies in the United States, including auto body primers in colors.

With high-heat resistant powder coatings, the automobile aftermarket has started powder coating car mufflers to resist corrosion, protect against nicks, and prolong the life of the muffler. Pick-up 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.

Powder coating plastic surfaces represents a major potential growth area. Powder manufacturers are working with the automotive industry to develop powders and applications to perfect powder coating on items such as wheel covers, rear-view mirrors, door handles, air conditioning vents, and interior clothes-hanger hooks.

Appliance Industry

The appliance industry uses powder coatings on refrigerators, washer tops and lids, dryer drums, air-conditioner cabinets, water heaters, range housings, vacuum cleaners, dishwashers, microwave oven cavities, and freezer cabinets. In some applications, pre-coated blank stock is coated and then post-formed in the desired shape. Even, thin films with high levels of resistance to chips, impact, detergents, and chemicals are critical to the appliance industry.

Architectural & Construction Industry

The architectural and construction industry powder coats aluminum extrusions used on windows, doorframes, building facades, kitchen, bathroom and electrical fixtures, and modular furniture. Many highway projects use powder coating on light poles, guard rails, posts, road signs, and fencing.

Lawn & Garden Industry

In addition to most metal patio furniture, powder coating is used on numerous outdoor home products such as lawnmowers, wheelbarrows, snowblowers, snow shovels, barbecue grills, propane tanks, and garden tools.

General Consumer Goods Industry

Everyday uses for powder coated products include lighting fixtures, antennas, and electrical components. Schools have bleachers, soccer goals, basketball backstops, lockers, and cafeteria tables that are powder coated. Farmers have powder coated tractors and agricultural equipment. Sports enthusiasts use powder coated bicycles, camping equipment, golf clubs, and golf carts, ski poles, and exercise equipment. Office workers use powder coated file drawers, computer cabinets, laptop computers, and cell phones. Parents have powder coated baby strollers, cribs, playpens, car seats, toys, and wagons. Homeowners have electronic components, gutters and downspouts, bathroom scales, mailboxes, satellite dishes, toolboxes, and fire extinguishers that benefit from a powder-coated finish.

Military & Defense Industry

The military is a growing industry for powder coatings. The Naval Air Force rehabilitation and repair facilities have used powder for recoating on parts for ships for many years now, including water-tight doors, ammo lockers, railing, bunks, and lockers. Some military ordinance is powder coated and Chemical Agent Resistant Coating (CARC) powders are used on military vehicles. With increasing interest in limiting VOC, military hardware will be a growing market for years to come.

Powder coating may have gotten its start as a superior finish for metal products. In fact, powder coated products are everywhere—in your home, office, shopping mall, automobile and SUV, stadium and playground and in countless architectural applications. Regardless of the product or use, you can always count on powder coating to deliver a superior finish with the Five E’s always in mind:

• Efficiency
• Economy
• Energy Savings
• Environmental Compliance
• Excellence of Finish

Efficiency

With powder coating as the finishing process, there are no runs, drips, or sags. Since no drying time is required, a powder coating production line will move more efficiently than a standard paint line. More parts are able to be coated automatically, too, with significantly lower reject rates. And, with the use of appropriate application equipment, materials, and recovery methods, a 90% to 95% transfer rate is achievable.

Economy

In addition to its efficiency, powder coating offers a simplified line process that allows for minimum operator training and supervision. Parts can be racked closer together on the conveyor and pass more quickly through the production line, allowing for lower per-unit costs—which means greater economy. Powder coating also offers easier compliance with federal and state regulations, increasing cost-effective savings.

Energy Savings

Utilizing the strength of powder coating’s efficiency and economy, the exhaust required in powder coating ovens is lower and therefore helps reduce energy consumption. While ovens that cure solvent-based coatings must heat and exhaust huge volumes of air to protect against potentially explosive fumes, the exhaust volume of a powder coating oven is lower and more manageable. So much so that the air is able to be recycled into the plant.

Environmental Compliance

Powder Coating’s efficiency, economy, and energy savings work for the environment as well, as this process eliminates VOCs – meaning the air is environmentally safer. Installation, expansion and running of a powder coating operation are significantly simplified, creating the potential to place a powder coating finishing operation in areas where other production systems would not be permitted. The employees also love powder coating’s reduced housekeeping problems and minimum contamination of clothing, since dry powder does not emit the kinds of fumes liquid paint does.

Excellence of Finish

Above all else, powder coating’s efficiency, economy, energy savings, and environmental friendliness produce excellence and superiority of finish that customers will come to know and count on. With its two application types (Thermoplastic and Thermosetting), powder coating offers a wide range of both extreme and decorative performance properties. Color selection is virtually unlimited, and is available in both high and low gloss.