Classic & Vintage - Best ways to remove aluminum oxidation?

I have some aluminum chainguards that have patches of severe corrosion-- in places it has eaten right through to the other side. Obviously there's no way to restore these and replace the missing material, but is there a chemical that will eat through the oxidized part leaving the intact aluminum nice and shiny? Sort of like an aluminum equivalent of OA? My goal is to remove whatever corrosion I can, polish up, then clearcoat.

These are the guards in question. Poor pic, but notice the dark patches of corrosion. My normal method of scrubbing with steel wool and dish soap didn't polish them up nearly as well as it works on chromed steel:

E.G.

0000 Steel wool, Mothers Aluminum Mag polish and E.G. (elbow grease).

Would also love to hear if there is an easier way.

Duragloss auto products makes a aluminum cleaner.Acid base (hydracloric)?It removes the Aluminum oxide coating that forms naturally on aluminum just not sure if it will do anything for the corrosion.

They do make a zinc/aluminum brazing rods.
I picked some up several years ago at the Portland swap meet and repaired some alum bits.The guy selling them demonstrated them by welding up holes in coke cans with a little hand held map gas torch.

http://www.hobartwelders.com/weldtalk/archive/index.php/t-10709.html

Edit:Another thought is to use a stainless steel wire brush on the corrosion then polish.We use stainless brushes on alum. to prep before welding.

Auto parts stores carry Aluminum Mag wheel cleaner/sprays. Make sure it's the can for bare aluminum, not painted/clearcoated finishes.
Works like oven cleaner only milder.

There's also the stuff that they sell to get the oxidation off of aluminum storm window and doors .. not sure the name of it ..

Scott

Make sure first that you are not dealing with anodized parts as you will need to remove the anodizing if you are even going to make a dent on removing the oxidation. removing the anodizing is easy enough by using oven cleaner spray.
It really depends on how deep the oxidation had worked into the aluminum if it is not too deep, just a bit of elbow grease and some polishing compound past might make it dissapear very quickly. If the oxidation is deep, you might have to use a buffing wheel and buffing wheel compound to get down below the level of the oxidation becasue if you do not take off enough material, you will end up with pits on the surface. Be careful with thin parts like those chainguards might be, as you can overheat and warp them if you apply too much pressure with the buffer. This polishing might result in a mirror finish that you might not want, but it is easy enough to use a fine Scothcbrite pad to get a more directional satin-like surface if you want it that way. just experiment with the Scotchbrite. What is good is, you can always erase what you have done with the buffer and start over again if you do not like the results.

Good luck and tell us how it goes!

Chombi

Using acids on aluminum is very tricky. I do a lot of weld repairs on aluminum pieces and have all the acids that are sold for this purpose and they are pretty useless. Nothing like Oxalic acid.

I have a large vibratory finisher that is basically a box of rocks that vibrates like crazy. Some of the rocks are pointy and some are round. It seems to "smooth out" surface variations. It can't do a full polish but it will smooth it out without removing more than a 'thou or so (.001")

The kids around here have me VF the valve covers on their "tuners" (small cars with bald tires) before they polish them.

We can give it a whirl if you like ?

E.G.

0000 Steel wool, Mothers Aluminum Mag polish and E.G. (elbow grease).

Would also love to hear if there is an easier way.

This is what I've always done and it seems to work. I usually alternate between a steel or brass bristle brush for really tough spots. Although I don't think I've ever had to deal with "extreme" oxidation.

Steel wool + aluminium = disimilarity of metals.

Not a good idea.


Regards,
J T
EOM.

Has anybody thought about pouring these products down into your seat tube to possibly break free stuck aluminum seatposts in steel frames?

They sell "Aluminum Jelly" that works on aluminum the way "Naval Jelly" works on iron rust.