What Is Powder Coating, How to Do It Yourself & Much More!

The powder coating industry has enjoyed healthy growth over the last few decades, expanding into an $11.6 billion global market in 2020.

As the technology, tools, and materials become more refined and accessible, powder coating has arisen as a promising alternative to traditional liquid paints, offering better performance and a lower environmental footprint.

If you’re an aspiring detailer, automotive painter, or just a car enthusiast, looking for the best finish on your wheels, engine bay, chassis and suspension components, trim pieces, and even interior bits, you can’t ignore the numerous benefits of powder coating.

In this article, we’ll talk all about powder coating and give you all the information you need to decide what painting method is best for your needs and vision.

Powder Coating In The Automotive Industry

Powder coating was invented in 1945 by inventor Daniel Gustin as an alternative to traditional liquid paints, which outgas volatile organic compounds and require skillful hands to produce a consistent, high-quality finish.

In the 1970s, auto manufacturers recognized the effectiveness of powder coating for protecting engine bay and suspension components from corrosion, chemicals, and weathering.

In the 1980s, wheel manufacturers started applying powder clear coats to bare aluminum wheels to reduce corrosion and keep their appeal for years to come. As the aftermarket wheel industry exploded, a vast variety of powder coated finishes became available, with different colors, textures, metallic effects, and gloss levels.

Today, powder coating is also used for interior and exterior trim components. The popular black-out trim on many performance vehicles is created through powder coating these components.

Thanks to powder coating, modern engine bays look as much art installations as they do functional mechanical elements. The block, heads, valve covers, intake manifolds, fuel injection rails, and other parts are all powder coated, protecting them from corrosion and the elements, as well as giving them a flashy decorative finish. Special heat-resistant materials are used for powder coating exhaust manifolds, hot side turbo housings, exhaust pipes, and tips.

Powder coating is used by FCA and GM to prime body panels before color coatings are applied. BMW and Volvo even use powders for the surface clear layer on top of the paint, with the Big Three also testing the method in their product lines.

Powder coating has become the norm for off-roaders, trucks, dirt bikes, rally cars, and other vehicles that work in challenging environments and require highly durable finishes.

What Are Volatile Organic Compounds?

Traditional paints are made out of solid pigment powder particles mixed with various organic solvents, resins, and other additives. The solvents act as carriers so the paint can be applied and kept on the surface until it adheres.

Evaporating into the atmosphere, these solvents release volatile organic compounds - and they’re not good for you or the environment in the slightest.

Prolonged exposure to VOCs will irritate the skin, eyes, and respiratory tract, as well as damage internal organs such as the lungs, kidneys, liver, and central nervous system. Some specific chemicals are linked to cancer in animals and even humans.

Exposed to sunlight, VOCs react with NOx emissions to form ozone low into the atmosphere, creating thick smog over urban areas. This causes its own set of problems in terms of air quality and resulting respiratory illnesses.

At the industrial scale, more than a hundred million tonnes of VOCs are released into the atmosphere each year. Liquid paints are one of the biggest sources of man-made VOCs, so the EPA has regulations in place to limit emissions. Manufacturers and paint shops must use specialized equipment to scrub VOCs from the air before they escape into the environment.

How Does Powder Coating Work?

Here’s a rundown of the powder coating process.

Depending on the product, liquid paints and coatings can contain between 5 and 380 grams per liter of volatile organic compounds.

In comparison, powder coatings contain less than 2%. The same amount of powder you apply ends up as the final coating after curing, meaning there’s virtually no outgassing or waste.

But how do you apply any finish without liquid carriers?

Powder coating is possible thanks to the fundamental principle of electrostatic attraction. Electrostatic attraction dictates that two particles with opposite electrical charges (electrostatic charge) will be drawn together, while identical ones will be repelled. It works the same way magnets do, only with fundamental charged particles. You’ve already seen it happen when you rub a balloon over your hair and hover over shredded paper.

In order to understand how this principle applies to powder coating, we must look at the anatomy of the powder coating gun.

The dry powder is contained in a hopper. A low-pressure air compressor draws the powder through the barrel and shoots a small cloud out through the nozzle.

If we left it at that, the powder would simply bounce off the metal and fall down or carry through with the airflow. It wouldn’t cover the part at all. However, if we induce opposite charges in the powder and coated part, they will stick to one another.  

A high-voltage generator is connected to an emitter rod in the center of the barrel. The generator produces up to 100,000 volts, creating an electric field around the tip of the rod, splitting the surrounding air into free-flowing positive ions and electrons. As the powder is blown through the field, it picks up free electrons and becomes negatively charged.

The coated part is always grounded, so electrons in the metal vacate the surface, leaving it positively charged. And there we go, the negatively charged powder is attracted to the positively charged surface and attaches firmly, allowing us to build a thick coat on the part.

Once the part is sufficiently coated, it goes into a curing oven to cure at 400 degrees Fahrenheit for 30 minutes. The heat melts the powder together, producing a consistent layer with a strong bond to the part.

Whatever powder falls on the ground can be collected, cleaned, filtered, and reused again in the same manner. There’s very little waste in the process, making it an incredibly efficient way to transfer paint to the part.

Powder Coating Vs. Liquid Paint

VOCs aside, which one should you choose - powder coating or traditional liquid paint? Let’s look at the differences.

Powder coating creates much thicker layers, as more powder can build up on the surface due to electrostatic attraction. Too much liquid paint will start to drip and streak, producing an awful finish.

Typically, powder coatings have a thickness of 6 to 12 mils, whereas the whole multilayer paint on body panels (primer, color, and clear) is between 2.3 to 7 mils thick.

Depending on the powder used, coated parts exhibit exceptional corrosion and chemical resistance.

Because of the curing process, powder coated surfaces have a harder, more durable finish, resisting much more mechanical abrasion, scratches, chipping, and other degradation. Powder coatings can last anywhere up to 20 years - twice as long as traditional paint.

Due to the even electrostatic forces, powder is distributed uniformly across the surface. Once cured, it forms a consistent finish with virtually no imperfections, which can rarely be said of liquid paints. In that sense, an inexperienced painter will produce much better finishes with powder coating than liquid paints.

Finally, powder coated products cure in an oven. They come out in under an hour, and after cooling to room temperature, are ready for installation with no further outgassing or curing needed. Liquid paints need to dry for at least 24 hours, and continue to outgas for weeks and even months after the parts are installed onto your vehicle.

In short, powder coating outperforms liquid paints in most significant ways, but not ALL.

Powder coating is a more complicated process, and your first attempt will likely be a failure. It requires specific equipment and a dedicated oven. The cost to acquire these is not astronomical, but higher than a rattle can or a spray gun. Unless you plan to powder coat many parts in the future, it’s hard to justify going through all the hassle and dedicating precious garage space.

Powder coating is not suitable for plastic, rubber, resin, and other materials that melt or deteriorate when heated. There are UV-cured powders, but these are too exotic for the scope of this article.

Generally, powder coatings cannot produce thin films, and the finished coatings often weigh twice as much as liquid painted coatings. When minimal weight and thickness are required - for example, on full-tilt race cars - you’re usually better off with liquid paints.

Powder coating provides many options for custom colors, effects, and gloss levels. However, it cannot compare to the near-infinite options available with liquid paints.

Price-wise, you’d pay a similar amount to get parts painted or powder coated at a professional shop. However, due to the cost of powder coating equipment and the mass manufacturing of liquid paint products, it’s usually cheaper to use traditional paints at home.

Types Of Powders

If you’ve decided to powder coat your parts or wheels, you should be aware that there is a wide range of materials that produce different properties in the finished product.

Regardless of the chemistry, the majority of powders are available in different colors, finishes like gloss or matte, and even special effects like metallic flakes, translucent, and color blending effects.

Powder coatings have limitations, and for the most part, they are harder to customize in comparison to liquid paints. That said, everyone but the pickiest should be able to select a finish they like.

The two main chemical kinds of powder coating are thermoplastic and thermoset. Both have different use cases and different application processes. Thermoset is the most common. However, beyond those two different processes, there are several different types of powder that you ought to be aware of. Let’s go over them.

Polyester Powder

Polyester powders are the most commonly used, encompassing more than 60% of the American market. They have good UV and chemical resistance, good durability, and an excellent surface finish.

The most commonly found variant is the TGIC (Triglycidyl Isocyanurate) powder.

TGIC-free powders are commonly used in Europe for their environmentally-friendly composition and lower toxicity.

Polyurethane and Super Durable Polyester powders are higher-grade variants in this group, offering better corrosion resistance, higher durability, and longer life.

Fluoropolymer Powder

Fluoropolymers (otherwise known as Teflon, PTFE, etc.) are the Cadillacs of powder coating. They are amazing at everything - chemical, UV, and weather resistance, consistent and durable finish, and more. Fluoropolymers are most valued for reducing friction in moving components and creating non-stick surfaces.

Epoxy Powder

Epoxy powders have great adhesion and high resistance to chemicals, salts, and corrosion. However, they have very poor UV resistance, which is why they’re primarily used for indoor applications or as primers for a different top coat.

Acrylic Powder

Acrylic powders are commonly used for clear coats in the automotive industry. The majority of aluminum wheels are clear coated using acrylic powders. They cure into a clear, smooth surface that doesn’t chip or crack easily, and can endure the harsh conditions and strong cleaners that wheels are exposed to on a daily basis.

Silicone Powder

Silicone powders are used in high heat applications like exhaust manifolds, turbos, heat shields, and other engine bay components. When cured, these form a ceramic layer over the part, insulating the heat from penetrating through the part and damaging more fragile components. They also protect against all types of corrosion.

Can You Do Powder Coating At Home?

That’s the million-dollar question, isn’t it? Well, no. It’s a several thousand-dollar question for a professional paint shop and a few hundred dollar question for the garage.

DIY powder coating kits come as cheap as $100-$150 USD, including the gun, high-voltage generator, and compressor. It’s more expensive to get an individual component powder coated at a professional shop.

It’s really tempting to give it a try, but before you order your powder and kit, there are a few things we need to talk about.

Safety Procedures When Powder Coating

Powder coating is the most environmentally-friendly method to paint a part. However, that doesn’t mean it’s not hazardous for you, the painter.

1. Don’t breathe or ingest the powder. It’s toxic when consumed and poses a much bigger hazard for your health if not properly handled. You need a good mask and eye protection. It’s best to use a full face shield.
2. Get a dedicated ELECTRIC oven for curing your parts. You can use any oven that will fit your parts - even a toaster will work. However, you can’t EVER cook food in the same oven you cured your powders. Heating the powders releases toxic fumes that will contaminate the oven permanently.
3. Keep flames and sparks away from raw powder. The powders are highly flammable, and you can accidentally set a huge fire and get hurt. Obviously, you don’t want to smoke around your powders, but also take extra precautions to remove any ignition sources from the area when you’re powder coating.

Beware of electric shock. Don’t touch the emitter rod, powder, or part while working. Hold the gun with a bare hand to ground yourself and triple-check the grounding wire to the part before you begin coating. Touch the ground to the emitter rod to discharge any static electricity before putting your equipment away.

Prepping A Part For Powder Coating

Just like regular painting, before you begin powder coating, you must sufficiently prep the part. The prep work plays a critical role in the quality and longevity of the finish, so you want to be absolutely meticulous.

1. Strip the part to bare metal. Remove any grommets, bushings, bearings, seals, wiring, plastic, and rubber components that may get damaged in the subsequent curing process.
2. Remove the old paint completely. It’s best to sandblast the part and bake off the remaining contaminants. A paint stripper is an effective but significantly toxic and polluting alternative. A grinder might be the perfect option if your part has simpler geometry, but definitely put a mask on, as you don’t want to breathe in any paint dust.
3. Deburr and grind sharp edges. Powder will build up in these areas, producing ugly artifacts and becoming prone to chipping.
4. Clean the part with degreaser and acetone. Remove any contaminants and oils from the part, exposing a perfectly clean surface for the powder to adhere to.
5. Plug threads and holes and tape off surfaces you don’t want powder coated. Powder coating produces thick finishes that will interfere with the normal operation of threads and other functional surfaces with tight tolerances.

Coat your parts directly on the oven rack. The rack gives you access to all sides of the part and makes it easy to put in the oven without touching it. Hang the part on the oven rack using wire. Make sure the wire is stainless steel or another conductive metal to promote proper grounding.

Applying A Powder Coating

Once all the prep work and safety measures are completed, you’re ready to start powder coating. Consult the owner's manual of your equipment and chosen powder for the exact settings. However, here’s what you always need to keep in mind:

1. Connect the ground wire to the part or oven rack. Make sure the connection is good - otherwise, the powder will not properly stick.
2. Generator settings. The kilovoltage setting controls the strength of the electric field generated, while the microamperage (if your unit has one) controls the intensity of the charge. You want higher voltage for flat surfaces with larger areas to cover. Conversely, you want smaller voltages and smaller amperages for complex geometry with crevices and curvature, where the Faraday cage effect can occur and deflect your powder.
3. Compressor settings. Air pressure is needed to disperse the powder in a tight cloud, but you want to keep it under 10 PSI - sometimes half of that - to avoid blowing away and wasting material. You can run higher pressure/airflow when you’re covering large areas with simple geometry and tone things down when you’re getting into tight spaces.
4. Spray distance. You want to keep the tip of the gun about 8 inches from the surface. Start away from the part to ensure you’re getting a uniform cloud. Then, try to coat the entire part in one pass, without releasing the trigger. Use smooth motions, overlapping side to side and top to bottom movements. Inspect the coating for uniformity and consistency. Touch up with extra powder if needed, but be careful not to add too much.

Cure the powder. Once the coat is sufficient, you have to cure it in an oven at 400F for 20-30 minutes. The exact temperature and cure times will be specified on the powder you purchase.

Clean-Up And Disposal

Since these powders are chemical products, you want to dispose of them in a safe and environmentally-friendly manner.

The first time around, you’ll notice that you get considerable overspray and wasted powder on the floor. This is normal. As you get better and dial in your settings properly, you’ll get more powder on the part and less on the floor.

Still, there’s always going to be some wasted material. The best way to clean it off the floor is by sweeping it with a broom. Again, take all fire safety precautions when handling the material.

Typically, waste powder can be recycled, but it requires special equipment. The best way to dispose of it at home is to collect it into an oven bag, then bake it until it solidifies. Once cooled, it will become an inert block of polymer material that will not react or harm the environment, and you can then safely throw it away.

Summary

Powder coating is an entire industry that can’t be fully explored in a single article. However, you should now have a pretty good idea of what powder coating is, how it works, when it’s used, and whether it's the right finish for your automotive components.

Overall, powder coatings offer superior corrosion, chemical, and mechanical protection compared to liquid paints. They produce highly uniform coats with high-quality finishes that are suitable for all types of metal parts, including the engine bay, chassis and suspension components, wheels, and even interior and exterior trim pieces.