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Old 11-06-2003, 01:33 AM
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Question Campagnolo Magnesium wheels - Can anyone help?

I have 2 sets of original Campagnolos magnesium wheels;
GTA1600 6Jx14 and GTAm style 6Jx13.

When I bought the 6x14 set I tried to restore them.My wheels' restorer said that he will put them in the ''oven'' for an ''electrostatic spraying''. I told him that as I have heard you cannot paint magnesium but you can only ''clean'' it with chemicals - or I don't know what. He insisted on painting them and as you can see he failed because when he sprayed them, they started ''spitting'' any colour he sprayed on (he must applied 7 or 8 coats) and their surface became full of bubbles.

Does anyone know what you can do with magnesium?
Where are you ''Borrani'' or anyone else, any ideas?
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Old 11-06-2003, 01:41 AM
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I hope you can see bubbles here.
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“Alfa Romeo is not merely a maker of automobiles : it truly is something more than a conventionally built car. It is a kind of affliction, an enthusiasm for a means of transport. It is a way of living, a very special way of perceiving the motor vehicle. What it is resists definition. Its elements are like those irrational character traits of the human spirit which cannot be explained in logical terms. They are sensations, passions, things that have much more to do with man’s heart than with his brain”.
Orazio Satta

gt1300junior, '67
gt1600junior, '73
giulia 1300 ti, '67
giulia sprint gt, '64 (needs heavy resto)
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Old 11-06-2003, 06:43 AM
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Is this a powder coat? It's probably not a good idea to put magnesium wheels in an oven. I believe the oven temp for powder coating is 400 degrees F. That's probably not going to be good for the wheels. Paint should stick just fine to those.
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Old 12-02-2003, 05:53 PM
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Very interesting! It looks like the 14x6 wheels have very thick paint on them? Much of the definition around the holes is lost, as is the classic rough finish.

Steve S.
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Old 12-02-2003, 06:28 PM
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The 'bubbling', as it occurs in powdercoated cast parts, is called 'out-gassing'. It occurs when tiny pockets of gas left in the metal from the casting process rise to the surface when heated. The gas will break thru the curing powder and look like bubbles. The way to prevent outgassing from ruining the finish is to pre-outgas the uncoated part first. Just stick it in an oven that's at a higher temperature (450 F) than the cure temp (400 F).
Don't know how safe that would be for a mag wheel though.
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Old 12-02-2003, 08:46 PM
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Who's going to see the bubbles when you're doing 100 mph?
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Old 12-03-2003, 09:36 AM
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When I first got into Alfas I wanted my turbinas powdercoated. I called a company that did that and he told me that magnesium is an "active" metal that has oxygen in its structure. Like Papajam says it out gasses, but there is no way to stop it. That's why magnesium burns ( just ask a long time VW enthusiast about throwing an old engine block on a campfire ). All you can do is give them a nice coat of paint, but don't bake it on.

Dan

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