Bead Blasting & Painting/Powder Coat Wheels

[Bob Coury]

I have read the several posts reguarding cleaning and painting or PC wheels made of magnesium. The posts have generated some questions while thinking of how to clean up some Dymags.

1. Any preference between PPG DP90/Omni MP170 Epoxy Primer vs Powder Coat?

2. I don't want to burn down any business or damage the wheels-what temp is it safe to bake the wheels at if they are powder coated?

3. Does anybody know of any fire hazard if magnesium is glass bead blasted?

4. Has anybody chemically stripped the finish before painting?

I cleaned some of the wheels and roughed them up before painting with Dupi Color wheel paint last year, and it did not hold up as well as I would have liked.

Thanks
Bob

[R. Pare]

Personally, I like the DP90. It is not only tough, but is also a conversion coat that helps keep the wheels from corroding, which mag loves to do really quick. Never tried the Omni.

No fire hazard as long as you do it out in the open air. I would think that doing it inside a bead blaster might make the box an explosive.

When bead blasting, always use new, clean, media. Media that has been used to blast steel can imbed the steel powder into the mag, making it corrode quickly.

Chemical stripping is the standard way to clean them before and conversion coating - you just have to get all of the chemical off before painting.

[reidhazelton]

The PPG/Omni is good stuff. Go for the Omni, it is nearly identical to the more expensive PGG stuff, like the DP series epoxies. It is not UV protected, so in the sun over time it will get foggy and start looking gray.

Blast it, epoxy it within 4 hours, and then and hour after that cover them with paint.

Or just send em to be powdercoated and be done with it. Any fluids, brake fluid/gas/oil, will dissolve the paint/epoxy anyway. Powdercoating is much more durable and will take frequent washings, chemicals, heat and so on, much better. Think about all the crap that the wheels get bombarded with. I'd powdercoat em, and I would guess the cost would be the same if not less once you figure in paint/time/hassle.

Don't quote me, but powdercoating is done at about 500* maybe?? The last peice of magnesium we threw in the ole bonfire took a lot more heat than that to light. The heat from an asphalt torch.

-RH

[BruceRace]

When powdercoating "Mag" wheels, ask the powdercoater you choose if they have experience with Magnesium. I had a set done a few years back, by a company called "Cincinatti Powdercoat". They found they had to "pre-heat" the wheels to within a few degrees of the powder "melt point". The reason is that some magnesium gets very porous when heated, and it creates "bubbles/pock-marks" in the finish. They heated the wheel first, opening the pores , then applied the powder on the "almost" hot wheel, then heated to the desired point. The end result was a very smooth finish. Very durable ( but it did not hold up well to concrete at 115 MPH!!!!!) P.S. I don't know if that company is still in business, as I was not able to contact them last fall to coat other wheels.

[reidhazelton]

Bruce-

Very interesting!

Thanks for the info.

[cjahn]

Hi folks,

I tried painting my mag wheels and even baking it on, and a number of methods. When the tire guy got them, and mounted the tires, the paint was rubbed or chipped off... (Just a little bit but enough to be anoying after spending the effort to make them look nice - A known tire guy who is very careful when mounting tires. I watched it happen). This may have been related to preparation or the paint, although I thought I prepared it adequately.

I had a set coated here and I am amazed at the results... http://www.classiccoatings.com/

They stripped them (blasting), and recoated them. Black mirror finish. This made an UGLY set of wheels look just plain fantastic.

Corky!

[John LaRue]

I had my Techno's blasted and then simply painted them with the DP90. They have lasted for years with the normal wear and tear of tire changing and continue to look great.

[revtom]

Powder coating wheels does give a nice, lasting finish, but is such a thick coating it will make crack detection very hard, and for that reason, most avoid it. Kefos treatment, or reasonable thickness epoxy primer will be much better in this regard.

[Don Becker]

Have them Kephos coated if black is ok. Not expensive, crack checking is no problem. The finish is bulletproof and very thin, the magnesium is the softest part. If the tire guys take reasonable care the finish will hold up much better than paint or powdercoating.
www.kecocoatings.com

North Carolina or Indy locations.

[thomschoon]

Do your research, www.finishing.com can provide some information but the obstacle is not just the porosity issue it is how the heat cycles age the magnesium and reduce the strength. This topic was researched for the coating of aerospace components and there is a number of cycles that are allowed and it is temperature based, meaning above 250/275f you get less life, many low temp powder coatings cure in this range so research and make an informed decision. Good luck

[Bob Coury]

Gentlemen:

Thanks for the responses. Since things are tight, I think I will blast outside myself, and shoot with the Omni (made by PPG) epoxy @ 30 bucks a qt vs the PPG at 80 bucks or so. I spoke to PPG and it sounds like they are almost the same products.

Mr Pare-you are so right about about the carbon steel contamination. We have actually received some 316 SS fittings we get from a big name US manufacturer that they happen to tumble deburr with carbon steel parts-BEFORE they ship them to us to use in a saltwater enviorment!