What is it that makes powder coating so different from plain old paint? The answer is that powder coat paint is nothing more than a fine mix of ground pigments and resin. The coating process is pretty unique, too. Yes, it's easy to learn how to powder coating. You put your selected metal pieces on a rack where they will be sprayed and received the powder coat finish. Powder coating is a process by which selected items are sprayed with a powder coat gun and coated with the fine powder mixture. Then just like a Betty Crocker in biker black leather, pop them into the oven for heating and curing. I would suggest that you set aside a special powder paint oven to be used for this purpose alone. A powder coat finish is pretty but may not taste too good to be good for your health.

Powder coating is by far the youngest of the surface finishing techniques in common use today. It was first used in Australia about 1967.

Powder coating is the technique of applying dry paint to a part. The final cured coating is the same as a 2-pack wet paint. In normal wet painting such as house paints, the solids are in suspension in a liquid carrier, which must evaporate before the solid paint coating is produced.

In epoxy powder coating, the powder coat paint may be applied by either of two techniques.

The item is lowered into a fluidised bed of the powder, which may or may not be electrostatically charged, or The powdered paint is electrostatically charged and sprayed onto the part.

The part is then placed in an oven and the powder particles melt and coalesce to form a continuous film.

There are two main types of powder available to the surface finisher:

Thermoplastic powders that will remelt when heated, and

Thermosetting powders that will not remelt upon reheating. During the curing process (in the oven) a chemical cross-linking reaction is triggered at the curing temperature and it is this chemical reaction which gives the powder coating many of its desirable properties.

The coating compositions of this invention are dry, free-flowing powders that may be used in fusion coating processes. "Fusion coating processes" are here defined as those coating processes in which coating powder paints are distributed over a substrate (which may be hot or cold); and heat, supplied from the substrate or an external source, fuses the powders into a continuous film. Examples of fusion coating processes include fluidized bed, electrostatic spraying, hot flocking (with or without electrostatic spray), and cloud chambers. When coating powders are based upon heat curing resins, as is the case of the epoxy resins of this invention, sufficient heat in excess of that required to fuse the powders must be available to cure the coatings and fully develop their physical and chemical properties.

Powder coating compositions are known in the art which produce textured or wrinkled finishes. For example, U.S. Pat. No. 4,341,819, the teachings of which are incorporated herein by reference, describes an epoxy powder coating composition useful for producing wrinkle finishes.

Current techniques in formulating textured powder coatings require balancing particle size, resin-viscosity and filler loadings to restrict the melt flow of the material thereby causing a coating surface with various degrees of orange peel or texture. Uniformity of texture is somewhat difficult to achieve and control on a consistent basis due to normal variations in raw materials and processing. Many of these formulations are difficult to apply electrostatically because of the high filler concentrations needed to produce the desired texture.

An epoxy powder coating or powder paint is a protective material made from epoxy-based resin. It provides outstanding resistance to corrosive chemicals, heat, and ultra-violet light; has convenient drying times; exhibits excellent dimensional stability, extreme toughness, and abrasion resistance; and provides strong adhesion to a wide range of substrates, including glass, metals, fibers and numerous other modern materials. An epoxy coating may be used in a wide range of interior and exterior applications across many industries including building and construction, industrial, electronics, and agriculture.

Some specific examples serve to highlight the broad application of epoxy powder coatings. In building and construction, an epoxy coating may be used for high performance and decorative flooring applications, both in heavy foot and vehicle traffic areas and settings which require high aesthetics, such as colored concrete and terrazzo. In the marine industry, an epoxy coating is used as a primer to enhance adhesion of paints applied as a final coating to hulls and decks. An epoxy coating may also be used to protect the internal surface of fiber-reinforced hulls. In the food industry, an epoxy coating may be applied to metal containers to prevent rust and taste degradation.

Technically, an epoxy or polyepoxide coating is a thermosetting copolymer. It is a copolymer because it is formed from the combination of two different materials — an epoxide resin and a polyamine hardener. The hardener is effectively a catalyst that promotes polymerization. The polymerization process produces extensive cross-linking of the two materials contributing to the compound's strength.

An powder coat paint is thermosetting because mixing the resin and hardener triggers polymerization, or curing, that generates heat. The polymerization process can be controlled by carefully varying the proportion of resin and hardener and the prevailing temperature. Some applications benefit from extended curing and high heat. The curing period can vary from minutes to hours or days.

Prior to compounding, both the resin and hardener are liquids with low viscosity at room temperature and so can be easily handled. The quality of a finished product can vary significantly according to the precise proportions of resin and hardener used, however. The compounding may be performed by specialist firms if the ultimate user of the compound is not a large volume, experienced consumer.

Epoxy coatings and paints may be divided into two broad categories — a waterborne epoxy coating and powder epoxy coating. A waterborne epoxy coating is normally cured at ambient temperature. It is typically non-hazardous with low-flammability, facilitating transport and handling. The water base makes clean up easier.

An epoxy coating is usually cured under controlled, high temperature. It is used to produce the surface of many white appliances, such as washers, dryers, refrigerators, and so on. More sophisticated fusion bonded epoxy powder coatings are used to protect steel pipes from corrosion, particularly for water transmission. It is a high-performance material, the cost of which is usually justified in terms of an increase in the life of the equipment on which it is applied.

It looks like paint but it acts like armor, states the Powder Coating Institute (PCI) of this ubiquitous surfacing technique. Powder coating is a highly durable, decorative and long lasting finish applied to products of nearly every sort for the consumer and industry alike. It can come in virtually any color or finish, matte or smooth, is rust-free, scratch resistant and ecologically friendly.

Outdoor barbeques, swing sets, patio furniture and garden equipment are just a few examples of products that are powder coated. Though it appears painted on, it's actually a dry finishing process. Electrostatically charged particles of pulverized pigment and resin are sprayed on to the surfaces of items that have been electrically grounded, thereby attracting the dry charged particles. Items are then placed in a curing oven where the powder coat paint melts and fuses to the surface. Not only is the process virtually pollution free, but there is also very little waste as the dry overspray can be recovered. Also, the industry does not have to invest in costly pollution-control equipment, making powder coating extremely economical.

Resistant to chipping, and fading, colors of a powder coated item will remain true for many years. High gloss and low gloss finishes, even metallic and clear finishes, make it an ideal choice for stadium chairs, railings and structural enforcements, tools, engine parts, golf clubs, carts, ski poles, bindings, computer cases, farm equipment, exercise equipment, store racks, baby strollers and countless other products.

While epoxy powder coating started out as a finish for metal, advancements led to the ability to cure the finish at lower temperatures which opened the door to ceramics, plastics and even wood. A clear finish makes these products look new longer. Kitchen cabinets, office furniture, children's furniture, and toys have joined the ranks of products that benefit from powder coating.

If you have something you'd like powder coated it's as simple as finding a coater nearby. PCI offers a clickable map that will direct you to a list of coaters in your state. Some coaters only perform large industrial work, while others do both industrial and private or small jobs for single items, so check with the coater first.

PCI reports that powder paint is the fastest-growing finishing technology in North America, representing over 10% of all industrial finishing applications. With everything it has going for it from its versatility to being economical and environmentally friendly, that is a trend that is bound to continue.

1 Powder coatings emit zero or near zero volatile organic compounds (VOC).

2 Powder coatings can produce much thicker coatings than conventional liquid coatings without running or sagging.

3 Powder coating overspray can be recycled and thus it is possible to achieve nearly 100% use of the coating.

4 Powder coating production lines produce less hazardous waste than conventional liquid coatings.

5 Capital equipment and operating costs for a powder line are generally less than for conventional liquid lines.

6 Powder coated items generally have fewer appearance differences between horizontally coated surfaces and vertically coated surfaces than liquid coated items.

7 A wide range of specialty effects is easily accomplished which would be impossible to achieve with other coating processes.

While powder coatings have many advantages over other coating processes, there are limitations to the technology. While it is relatively easy to apply thick coatings which have smooth, texture-free surfaces, it is not as easy to apply smooth thin films. As the film thickness is reduced, the film becomes more and more orange peeled in texture due to the particle size and TG (glass transition temperature) of the powder.

For optimum material handling and ease of application, most powder paints have a particle size in the range of 30 to 50 μm and a TG > 40°C. For such powder coatings, film build-ups of greater than 50 μm may be required to obtain an acceptably smooth film. The surface texture which is considered desirable or acceptable depends on the end product. Many powder coating manufacturers actually prefer to have a certain degree of orange peel since it helps to hide metal defects that have occurred during manufacture, and the resulting coating is less prone to show fingerprints.

There are very specialized operations where powder coatings of less than 30 micrometres or with a TG < 40°C are used in order to produce smooth thin films. One variation of the dry powder coating process, the Powder Slurry process, combines the advantages of powder coatings and liquid coatings by dispersing very fine powders of 1–5 micrometre particle size into water, which then allows very smooth, low film thickness coatings to be produced.

Powder coatings have a major advantage in that the overspray can be recycled. However, if multiple colors are being sprayed in a single spray booth, this may limit the ability to recycle the overspray.

Powder coating produces a high specification coating which is relatively hard, abrasion resistant (depending on the specification) and tough. Thin powder coatings can be bent but this is not recommended for exterior applications.

The choice of colors and finishes is almost limitless, if you have the time and money to have the powder produced by the powder coating manufacturer.

Epoxy Powder coatings can be applied over a wide range of thickness. The new Australian Standard, "AS/NZS 4506 - Thermoset powder coatings", will recommend 25 micron minimum for mild interior applications and up to 60 micron minimum for exterior applications. Care must be exercised when quoting minimum thickness because some powder will not give "coverage" below 60 or even 80 micron. "Coverage" is the ability to cover the color of the metal with the powder. Some of the white colors require about 75 micron to give full "coverage". One of the orange colors must be applied at 80 micron. Color matching is quite acceptable batch to batch.