Not all trends are going to make a comeback. Thus far, bellbottom pants, 8-track audio tapes, REALLY short shorts on men, and unfiltered cigarettes have yet to return to the mainstream culture. However, the year is young, and the world is indeed a very strange place.
Standing in sharp contrast to these retired trends, is the age-old art of powder coating, a painting technique that borderlines on being something straight from a sci-fi flick. Thanks to advancements in materials and machinery, powder coating has made a massive return to the mainstream in recent years, offering those in search of surface protection every imaginable pigment.
Nowhere has powder coating seen more success, than in the aftermarket automotive sector. While this chemical rich compound can be shot on pretty much any material that can withstand extreme temps, the popularity of powder coated wheels in particular has really taken off.
But is this industrial-grade, custom pigmented protectant harmful in any way? Are there any drawbacks to having a set of wheels powder coated? And if so, do the pros outweigh these powder coating cons?
Today, we’ll discuss a slew of facts pertaining to powder coating and how it performs on wheels, as well as the protective properties this process provides. We’ll also delve into alternative ways to prevent aluminum pitting and corrosion.
Exploring the History of Powder Coating
According to powder coating pros, this painting technique was originally developed as a surface protectant for industrial and military applications in the 1940s. This treatment process proved to be so affective, that by the time World War II ended, more than 40% of all steel being used in the construction of bridges was being powder coated.
Back then, the process was far more archaic, with polymer powders basically being “flame-sprayed” onto metals, an extremely toxic and dangerous application process. It was not until German scientist Dr. Erwin Gemmer’s revelation that by creating a “liquid bed” for dipping materials, that airborne powders in fluidized form could be utilized.
By the time the 1950s rolled around, Gemmer’s “liquid-bed” application process was gaining in popularity both in Europe and America. Patent obtained in 1955, Gemmer and his ultra-thick powder coating were officially going toe-to-toe with paint for the corrosion-resisting crown, and they were winning.
But Gemmer’s ascent was short-lived, and his method was soon being bested by another scientist’s discovery. The year was 1960, and Amsterdam-based Pieter de Lange had just developed a thermoset powder coating substance that could be applied via an electro-static application method. While these processes may seem rudimentary by today’s standards, they are strikingly similar to the methods that are still being used today, thanks to de Lange’s use of a spray gun.
The advent of the electric spray method not only permitted the use of an easy-to-use gun (as opposed to a bathing process), but it also allowed complex industrial applications to benefit from a far thinner coating as needed. In no time, this evolutionary leap took the industrial coating world by storm, and the automotive sector in particular seemed ripe for the coating.
By spraying a grounded metal material with a silty, statically charged powder, electro-static spray-on powder coatings were able to cover all manner of surface with relative ease. They were also far less wasteful, safer to apply, and environmentally conscientious.
Today, powder coating is used as a means of corrosion protection on industrial materials, as well as in the automotive, food and beverage, fire safety, and outdoor furniture segments. Once cured, this substance looks all the world like regular paint, and most people go their entire lives without knowing that the products they use every day are powder coated.
Quick Nerd Note: Did you know that powder coating is often the preferred protective media for many of the items we encounter every day? A few of the more commonly coated products include: Vending machines, microwaves, antennas, basketball rims, refrigerators, fire extinguishers, ovens, patio furniture, bike frames, and outdoor furniture.
Understanding the Basics of Powder Coating
Now that we’ve gone over a little bit of powder coating history, it’s time we discussed how the stuff works, and why it matters.
Powder coating is an electrically-bonded powder that when sprayed, sticks to materials via a process called “electro-static attraction.” As the the atomized paint molecules are “misted” onto an object, they create a coating that can be baked into the surface via extreme heat. This is often achieved via the use of a kiln, or oven.
Once allowed to cool, the material is then coated with a second layer of electro-statically charged media, with this round consisting of a clear coat. The object is then baked one more time before being allowed to cool completely, at which point it is ready for use. This results in an extremely resilient painted surface that is far more environmentally-friendly than traditional paints, as it is not high in VOCs, and does not require harmful chemicals for clean-up.
Quick Nerd Note: Like almost any coating product, the trick to getting powder coat to stick, is having a clean surface for it to adhere to. This is why most professional powder coating companies employ some form of acid bath to first strip away any old paint, protective clear coat, or oil on an object, followed by a thorough sand-blasting process.
Why Do Car Owners Use Powder Coating?
In the automotive arena, powder coating is widely used on off-road racing vehicles, as it protects surfaces from sand, stone chips, mud, desert heat, and other organic ilk. It can also be sprayed in virtually any color imaginable, and then finished in various matte or gloss levels, making it extremely popular with aftermarket tuners, boat and ATV owners, as well as full-blown professional race teams.
As for the trend of powder coating wheels, there are typically two reasons why a car owner opts for this colorful aftermarket modification. While protection from corrosion, scratches, rock chips, acid rain, harsh chemicals, and other unsavory stuff are definitely at the top of the list in the practicality bracket, it’s powder coating’s dizzying array of customizable combos that really sucks people in.
Quick nerd Note: For those of you who may be worried that powder coating may add a lot of additional weight to those rollers, fret not. While powder coating definitely does add some grams to the overall weight of the wheel, it will not be detrimental to performance or wheel balance.
How is Powder Coating Applied?
Broken down to the basics, the powder coating process involves seven essential steps:
- Surface stripping, cleaning, and preparation
- Colored powder coating application
- First round of baking
- Clear coating application
- Second round of baking
- Final cool-down
Tips for Choosing the Right Powder Coating
There are two types of powder coating media that are commonly used today: Thermoset and Thermoplastic. While thermoplastic does not require baking, and remains recyclable, it does not offer a lot of protection from impacts and scratches, and will melt under high heat. Thermoplastic media is also sprayed onto pre-heated surfaces instead of being “baked-on,” and is commonly reserved for mechanical components, as it has the ability to be reshaped and molded as needed.
Thermoset, on the other hand, is a far more hardcore application due to it chemically bonding or “setting” atop a surface. Once baked for a specific duration of time in a temperature controlled oven, this media forms a super-strong structure, that once clear coated with a secondary layer of thermoset coating, becomes extremely resilient.
That being said, when we use the word “permanent,” we aren’t implying that a spritz of thermoset is going to last until the end of time. It’s just far more resilient than most coatings, and will not melt away like thermoplastic. So when in doubt, ask your local powder coating installer what they recommend for the item you want powder coated, and know that if it’s a set of wheels, they will more than likely suggest that you go the thermoset route.
What Prep Work is Required for Applying Powder Coating on Wheels?
Much like ceramic coatings, proper prep work plays a crucial role in the powder coating application process. Being that powder coating electrically-bonds to whatever surface it strikes, the importance of removing road grime, brake dust, grease, dirt, and every other ground-level contaminant imaginable from a set of wheels is pivotal in promoting adhesion. There’s also the issue of removing any blemishes, or “road rash” from the surface, for even those of us with substantial levels of driving skill occasionally encounter the rogue stone chip or unexpected scuff.
Regardless as to whether they are brand-new, or ratty looking as hell, in order for a set of wheels to be properly prepped for powder coat, they must first undergo the following prep stages. So bear this in mind when you head down to the local powder coating shop, because if they don’t do one (or some) of the following steps you’ll want to take your money elsewhere.
The Chemical Soak
The first prep procedure requires soaking the wheels in a specialized (often heated and agitated) chemical stripping solution. Stripped of residue and contaminants, along with any paint or coating, the wheel’s aluminum alloy underside will become exposed once rinsed. While there are several kinds of chemicals that can be used for this process, many of the older acid solutions are quite toxic to both humans and the environment. This is why it is important to ask what chemicals a company uses for stripping, because not all powder coaters rely upon earth-friendly systems like those offered by Greensolv.
Bake & Blast
To help expose any stubborn spots that the chemical dip may have missed, alloy wheels are often placed in the kiln after being rinsed off, which also helps expedite drying times. After that it’s on to blasting, a process that typically involves the spraying of aluminum oxide through a high-pressure hose to remove any debris that’s been lifted to the surface.
Manually Remove Any Rash
While blasting will remove most stubborn surface contaminants, it won’t do shit for deeply ingrained pitting and corrosion, nor make an impact on curb rash or rock chips. Any rough edges, imperfections, or unpleasant accidents should be shaved off with a polishing wheel, followed by a milder round of buffing.
Deburring and buffing complete, a thermal tape is brought out to protect anything that should not be powder coated. While some powder coaters will spray the whole damn wheel, the best shops mask-off the flat face that bolts to the hub in order to guarantee that the wheels seat properly.
Quick Nerd Note: Look for shops that only use aluminum oxide in the blasting process. Silica (sand) beads, walnut shells, and other are forms of organic media are quick to embed in softer alloys like aluminum.
The Powder Coating Application Process
While you can buy a powder coating gun online and bake freshly coated parts in your kitchen oven, this is not an advisable DIY approach, and won’t accommodate large components like wheels. That said, here’s how the pros prefer to powder coat a set of rollers.
Each wheel receives a center plug, and a threaded tightening bolt is fed through the air valve hole to allow the wheel to be suspended from a hook in the paint booth. The wheels are sprayed with a base layer of powder coating, which will provide both a core color and a smooth foundation from which to clear coat.
The Quick Bake
After the first coating is sprayed onto the wheel in the paint booth, the installer hangs the wheels on a metal rack that can be pushed into an industrial kiln/oven, where high temps will force the coating to adhere to the surface. Bake times for this first round are surprisingly swift, at just about 20 minutes, and temperatures in the oven typically hover at 400° Fahrenheit (204° Celsius).
Cool Down & Clear Coat
Removed from the oven, the wheels are allowed to reach room temperature, before heading back to the spray booth for clear coat. While satin powder coats typically don’t typically turn out well, flat and gloss clear coats turn out stellar, thus making them the top go-to options for powder coaters. One interesting note here, is that clear powder coats naturally come out milky white, and will not turn transparent until baked.
The Big Bake
Once the wheels have been completely covered with a clear coat, they head back into the kiln for a final bake, which typically lasts between 35-45 minutes at the same steady temp as before.
Rest & Rubber
Final bake complete, the wheels are set aside until they are completely cool to the touch. At this point any high-temp protective tape, hooks, and center hub plugs are removed, and the wheels are given valve steams and wrapped in fresh rubber.
Quick Nerd Note: After the chemical dip, gloves should be worn at all stages of the powder coating process in order to prevent imperfections from forming.
Pros and Cons of Powder Coating
Durable: When a thermoset powder coating is fully cured, it forms an incredibly strong bond with the surface, which on wheels will help prevent things like dings, scratches, and corrosion from forming.
Inexpensive: While pricing varies depending upon the installer, wheel complexity, size, and materials used, the average powder coating job for a set of aluminum alloy wheels runs about $400-$500 a set. Not bad, considering how long these coatings typically last, and the aesthetic perks associated with a freshly coated set of rollers.
Low Environmental Impact: Unlike traditional paint, overspray within the powder coating booth is minimal, and fumes are practically non-existent. Clean-up does not require solvents either, for there is no liquid to remove, which means breaking out an air gun is all that is needed in order to clean-up the booth between jobs.
Quality Control: The powder coating market has become fairly oversaturated in recent years, with many installers providing subpar services and cutting corners via the use of inferior products, tools, and procedures. Do your research, look-up reviews, and only agree to use a company that has a proven record of producing quality powder coated products.
No Hydrophobic Properties: Powder coating does not contain hydrophobic properties. This means that brake dust is still going to stick to a freshly coated wheel’s surfaces, as will grime, fresh asphalt, road salt, and every other imaginable form of nastiness.
Price: While paying someone $400-$500 to powder coat a set of wheels in the color and clear coat of your choosing may sound inexpensive to some, it is completely out of the question for most people. Being that many “bargain bin” wheel manufacturers are offering entire sets of wheels at these prices, the powder coating approach is a tough sale for those looking for little more than a quick aesthetic upgrade.
Is a DIY Ceramic Coating a Better Wheel Protectant Than Powder Coat?
There’s this myth that powder coating a wheel will protect it against rock chips, curb rash, acid rain, road salt, and other alloy eating contaminants. This is not true. While it may help impede the pitting process, and keep small scratches at bay, powder coating is going to scuff-off if hit hard enough or if exposed to corrosive chemicals for prolonged periods of time.
This is why more and more people are ceramic coating their wheels, straight from the factory. A high quality, 9H-rated ceramic coating has the ability to repel many of the nastiest contaminants on earth, and when applied to a brand new wheel, will add a dep layer of gloss that is impossible to ignore.
A nano-technology infused ceramic coating is also safe to use on any type of wheel, including aluminum, chrome, carbon fiber, steel, and more. It can also be applied on top of powder coating, which in many people’s opinion, provides the most resilient one-two punch for wheels, as road grime and liquids alike just bounce off the surface.
Quick Nerd Note: While there are quite a few different powder coating producers on the planet, Prismatic Powders and Tiger-Drylac continue to set extremely high standards within the market. The broad range of color options, pricing, and overall media quality has made both brands a favorite for powder coating powerhouses like Cincinnati-based Killer Koatings.
So after all these years, it appears that powder coating still has a home in the automotive world, and for damn good reason. It’s an outstanding solution for anyone looking to protect and/or customize raw metals, thus making it an ideal application for a plethora of automotive components, including alloy wheels.
That said, if you’re going to invest in powder coat, you might as well protect that investment with a layer of transparent ceramic coating. This will not only extend the life of the powder coating itself, but make the colors it contains truly “pop.”
At $70 a bottle, ceramic coatings like Armor Shield IX are cheaper than you’d think, and harness the ability to protect surfaces for 2 to 5 years. The first two years of protection are 100% guaranteed too, making ceramic coating the ultimate topical option for those freshly powder coated wheels you jus picked up.
Quick Final Tip: When it’s tire install time, always use a shop that has a “touchless” tire mounting system. Better yet, just have the powder coater install your fresh rubber, because chances are they have one of these “revolutionary” contraptions on premise. This will remove the risk of seeing your precious powder coated wheels being marred by some clueless technician with a pry bar and an archaic tire mounting machine.