Filling in pitted aluminium?

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Im attempting to refinish a set of old mirrors where the aluminium housings started to corrode with alu oxide and peel up the paint. I stripped the paint/wire brushed the surface clean, but there is small pitted bumps all over the surface. What is a good product to apply overtop to fill in the imperfections and can be sanded smooth to allow priming and painting? Bondo? Glazing putty? JB Weld? other?

Thanks
 
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Glazing putty if the pits are not too big. If they are everywhere, a sandable high-solids primer.

What, exactly, is the reason the aluminum is corroding? There generally has to be some environmental issue to cause it. High sulphur in your local environment, maybe? Air pollution can cause metals to corrode prematurely. If that's the case, you may want to consider an epoxy primer.

Aluminum oxidizes almost instantly upon contact with air. The oxide protects the underlying metal from corrosion. So for some reason that isn't happening in your case, something is interacting with the oxide and allowing it to corrode.
 
Not sure. Its a common problem on these mirrors. As most of the cars that these parts belong to have the peeling paint with white oxide forming underneath. But the pits are too deep for filler primer.
 
I have had great success filling aluminum pits with JB Weld.

I have saved many an aluminum intake manifold this way.
 
Whatever you end up doing, I would consider something like Xpel or a similar clear vinyl on top to provide an extra layer of protection. Mirrors are an "impact area" that tend to take a lot of hits from bugs, rocks, road debris, etc.
 
a lot of stuff folks think is aluminum is potmetal,zamak,or other zinc alloy.
you might be seeing potmetal cancer,zinc pest,ot other intragranular corrosion.
 
Use aluminium foil as an abrasive to clean it up and then continue with a binder. I use sunflower or boiled linseed oil as a binder but they take a while to set. An alkyd resin or a varnish might be an alternative.

Pits get filled with aluminium dust from the foil and whatever the base metal is.
 
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