refinishing magnesium wheels

[M Towsley]

Any thoughts out there on how to clean, prep and refinish the Shinn magnesium wheels. I've picked a couple of brains but am having trouble finding correct products to use. Also searched the Forum with negative results. I want to remove paint/minor corrosion and refinish/repaint. Thanks!

[Mark Julicher]

Re: refinishing magnesium wheels

My Shinn/Firestone wheels are cast aluminum. I am certain of this because I once had to do a welded repair Quite possible yours are the same. A small bit of metal filings from the wheel and a flame will be a definitive test.

If aluminum, you can just use aircraft paint remover from your local automotive supply store. Re-paint with epoxy enamel from a spray can and you will get decent resullts. More exotic finishes are certainly available.

If actually magnesium I would bead blast them clean and then treat with magnadyne conversion coating followed by epoxy paint. This is how I treated my control wheels (definitely magnesium according to the flame test )

[M Towsley]

Re: refinishing magnesium wheels

Thanks Mark. That's what I was looking for, Magnadyne Conversion Coating. I'll try the test, but I was advised by a knowledgeable person they were magnesium.

[Dano"T"]

Re: refinishing magnesium wheels

I sandblasted mine and powdercoated them with chrome colored powder coat...they look great!

[NY86]

Re: refinishing magnesium wheels

Magnesium is fairly easy to identify if uncoated. It turns a dark gray/black.

If you elect to blast it, be sure to use virgin blasting media. Any residual metal particles in the media will get embedded in the magnesium and cause corrosion down the line. Magnesium is at the end of the reactivity charts and is actually just corrosion in a highly unstable metalic form.

[hangarb7]

Re: refinishing magnesium wheels

Last year I wanted to refinish my magnesium control wheels, but I could not find an inexpensive powder coater. They wanted $100 per wheel.

I considered purchasing a cheap powder coater but a few years ago I purchased a cheap spray gun and it never worked correctly (you get what you pay for.... I have a second hand DeVilbiss that is sweet).

Next, I thought I would epoxy spray them. Two of you guys mentioned epoxy paint in the previous posts. I could not find any epoxy paint other than 1)spray cans of appliance type epoxy in white, black or sand colors, or 2) epoxy from a marine supply that was approx $50 a quart.

Sears, the local hardware, or any paint store doesn't seem to carry it anymore, and a search on the internet didn't help either.

I eventually sand blasted them and painted with extra-tuff outboard motor (below the water line, abrasion resistant) paint (laquer). They look great.

So, does anyone know where to purchase small quantities of epoxy in pints or spray bombs (other than the standard colors)? and also, Dano, I would love to see a picture of those powder-coat chromed control wheels. Sounds like the next thing to consider!

Thanks,

Jack Dernorsek
N44057
'46 BC12D

[M Towsley]

Re: refinishing magnesium wheels

I really don't want to cause a ruckus, but in my research for refinishing magnesium I noted a couple of articles about powdercoating magnesium. Basically, the articles said not to do it because of the heat involved in the powdercoat process and the magnesium was not to be heated like that. Just a word of warning.......if this really is the case.

[Robert Lees]

Re: refinishing magnesium wheels

No ruckus, I'm sure.

Im my experience, magnesium can be powdercoated. The problem is that cast magnesium contains inherent porosity, and the gases within expand during the heating process, which will bubble the paint.

The solution is to "heat-soak" the magnesium (takes hours, I believe) to get rid of these gases before the powder is applied.

Sounds like a specialist powder-coater is required, and not the normal run-of-the-mill place.

Incidentally, the heat required to melt and flow the powder is nowhere near enough to cause any combustion of the magnesium.

[M Towsley]

Re: refinishing magnesium wheels

Rob,

I believe that was the concern on the powdercoating, and that your everyday powder coater should not be used, but instead one that has dealt with aircraft parts, especially magnesium. Thanks.

[hangarb7]

Re: refinishing magnesium wheels

I had heard of this before (outgassing of the magnesium air pockets during curing of the powder coat, but I also heard that heat-soaking is the key), which is why I went the epoxy paint route, until I could not find reasonably-priced dark blue epoxy.

So my question still stands. Does anyone know of an outlet for small quantities of epoxy paint (pints or spray bombs) other than appliance epoxy at Sherwin Williams?

Inquiring minds want to know.....

Thanks,

Jack Dernorsek
N44057
BC12D

[M Towsley]

Re: refinishing magnesium wheels

Jack,

The modeling industry, I believe, has epoxy paints in small quantities and reasonable prices. It used to when I was heavily involved years ago. Check out Tower Hobbies, www.towerhobbies.com, for information or search for hobby epoxies. Hope this helps.

[Dano"T"]

Re: refinishing magnesium wheels

It really wasn't a big deal powder coating the wheels. We used a powder coat gun in my cousins' garage and heated it with a heat lamp. We checked the temp frequently with a laser monitor and voila!. The powder coat looks like fuzz before you apply the heat and it is really cool to watch the "fuzz" smooth out into a beautiful finish. It cost me ten bucks...but my cousin has the powder coat gun! We didn't get into worrying about trapped gasses and all that rubbish. I hope they hold up for many years. we did some samples in his garage and beat the sh** out of them with a hammer....that is some tuff stuff! It was very dificult to chip it even with a hammer.

[VictorBravo]

Re: refinishing magnesium wheels

Pick up a copy of a magazine called Flying Models. The reason for this is that they usually list all the hobby shops that carry the magazine, and you will probably find a local one. There are indeed some good 2 part model spoxy paints available in small cans. Years ago we had "Hobbypoxy" and "Superpoxy" but they may have gone the way of the dinosaur.

The other two or three model airplane magazines, RC Modeler, Model Airplane News, and Model Aviation would also give you some good references.

Call SIG manufacturing in Montezuma, Iowa, they manufacture a lot of finishing chemicals...if they don't have something they will know who makes it. One of their long time designers is a member of this forum if I recall, maybe Mike Gretz???

Call a company named Pactra, I think they make a good Urethane paint called Forumula U. They also were the ones that made Hobbypoxy if memory serves. A properly done Urethane paint on your wheels will be the closest thing to epoxy if you cannot find epoxy. Formula U is available in a lot of colors.

The two-part Stits Poly Fiber epoxy primer is a very good primer, and you could use this followed by any color paint and have a very durable protective coating.

Good luck,

Bill

[hangarb7]

Re: refinishing magnesium wheels

Here is what I found in the hobby industry...

Tower Hobbies only has light blue epoxy paint made by Coverite. It is marked as a low-price, special stock item; but Coverite does not show it on their web site, which tells me that they no longer make epoxy paints. I have an e-mail request into Coverite for more information.

Pactra is now owned by Testors Corporation, and according to their web site, they only supply Acrylics and Laquers; searching for epoxy or urethane or forumula U brings up zero. (Petit, I am told was the manufacturer of Hobbypoxy).

According to KEZ at RCGroups.com, " Just called the number. They said the Hobbypoxy paint was banned by the government and someone bought all his remaining stock a few months ago."

K&B made Ultrapoxy but apparently they no longer manufacture it as it says on their web site that once the present stock is sold, it will no longer be available. I have a message into them to see what is available.

A Superpoxy search brought this up...

http://www.klasskote.com They say that they make and sell a two part epoxy paint for models. I'll see what else I can find.

Thanks, all

Jack