Best type of clearcoat for wheel application

A. Hi Jan. I didn't realize that brake dust was hot, but I did know it's very corrosive to aluminum and should be washed off frequently. A traditional 2k automotive clearcoat should further protect your wheels. "Ceramic" clearcoats are becoming popular too, and are quite thin, one-half to one mil, but these are an alternative to paint and powder coating, they don't go on top of paint.

I put "ceramic" in quotes to avoid confusion because true conventional ceramic coating is actually done by flame spraying ceramic grit at a temperature of thousands of degrees to melt on a coating more similar to glass than to paint. But the more accessible "ceramic" coatings use a solvent/catalyst (possibly epoxy?) approach and oven baking.

There are also simple single-component clear coatings like Everbrite [a finishing.com supporting advertiser] and Protectaclear from Everbrite [a finishing.com supporting advertiser]. Send a pic of those unique wheels to mooney@finishing.com to decorate the page :-)
Luck & Regards,


Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. Dear Matthew,

I believe that the current status of technology is that powder coatings are the finishing system of choice for automotive wheels and rims. Two reasons: One is powder usually have a better abrasion resistance, chip resistance and surface hardness then liquid paints. Second powder coatings generally apply around two mils in a one coat application without dripping and sagging, so you are building a heavier barrier coat than you would with liquid coatings.

Not to mention the environmental factor.

Regards,

A. Dear Matthew,

We have done some work coating auto aluminum wheels with plasma deposited SiOx including filiform corrosion studies and APG and found excellent corrosion protection as well as ease of brake dust removal.

Regards,

A. You may want to explore catalyzed waterborne polyurethane-acrylate. It's VOC compliant, applies at 1.5 DFT and I have had excellent results on a west coast aluminum clad passenger railcar exposed to environmental extremes on the rail line (iron oxides, brake dust, water, washing solutions, etc.

A. Matthew,

We use a liquid clear coating application for preservation purposes. This coating has withstood the elements of weather and saltwater. In many cases, these objects have been used for its original function (i.e. boat propellers).

Todd

A. Hi, we find that for road trucks we get the best results by polishing the aluminum to the max. This maintains a good quality finish for about 100,000 miles with no protection whatsoever. We have no yellowing clearcoat, suffer little with pitting, suffer no cracking or floating that we often see with clearcoats & lacquers when subject to some of the extreme temperature changes that the wheels of a road truck endure. Maintenance is normally no more than regular washes. I have yet to find a clearcoat or lacquer that will outlast this time on o.t.r. trucks without yellowing or encouraging pitting and oxidization between the coating and the wheel. However, I have not encountered all of the clearcoats marketed and I am open to suggestions, and I am looking for a clearcoat for marine applications.

A. Have you considered powder coating?

A. Hi,

Automotive clearcoat is "two component" or "two pack"; the body shop mixes the two components and quickly sprays before the coating catalyzes and hardens. "Single component" over the counter stuff dries rather than catalyzes, and isn't as hard. It can be okay though and is simpler. Good luck.

Regards,

A. A solution to clear coating wheels is a clear ceramic coating. These coatings are non-stick and easy to clean. Embed themselves into the substrate so no liquid contamination occurs even if the coating is scratched or broken. This coating also does not yellow, grey or blue over and is very thin, meaning a polished wheel stays nice and bright.

A. Hi Doug. Machined aluminum anodizes better than pressure cast aluminum alloy, but the results will still depend on what alloy the wheels are cut from. Aluminum alloys all have other materials in them (copper, magnesium, zinc, etc.) which does not anodize like the aluminum does and can discolor it.

I think you're best off mechanically polishing the wheels to whatever lustre you like, and then clearcoating them. If practical, two or more thin layers to prevent pinholes. Chandelier manufacturers face different problems than you, but have been known to apply 7 layers of very highly thinned lacquer. Lacquer is not as permanent as some other clear coats but is relatively easy to remove with thinner and then re-do, which might be ideal for a show car which, because it is used, could suffer curb rash or corrosion and the need for refinishing.

Luck & Regards,

A. Hi Doug. We can't recommend brands or sources here, but there are a few different types of clearcoats. Two-part automotive clearcoats harden from a chemical reaction between the two parts rather than drying. Single part clearcoats dry when the solvent and/or water in them evaporates. Brass lacquers dry when the solvent evaporates. Radiation/UV cured clearcoats are generally not applicable for consumer applications like this, although the nail lacquer applied in some manicure salons these days is UV-hardened..

Two-part clearcoats tend to be harder than others for good scratch resistance, but more work and harder to remove, and some probably do look thick and plastic-y. I would probably go with a single part clearcoat (Everbrite [a finishing.com supporting advertiser] is an example). It is hard to estimate longevity because optimum longevity depends upon pretreatments like iron phosphating or chromating that aren't compatible with the desire for a clear bright finish. Looking at the discolored clearcoated aluminum wheels on Jeeps and other cars, I don't think you should count on maintaining show quality on an off-road vehicle for long, which is why something very easily re-doable can have an advantage.

I think a useful step that many people fail to think of is trying the finish on scrap. When your wheels were made for you does that company have a strip or two of the aluminum so you can try the automotive clearcoat and the brass lacquer on and see if you're happy with the appearance before proceeding on four wheels?

Luck & Regards,