Classic & Vintage - Oxalic Acid and OTHER metals?
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07-22-07, 11:05 AM
I love oxalic acid. I love it so much that I wish I had known about it years ago, and regret all those wasted years. There are still things I have yet to learn about it, though.
How does it affect other metals?
I recently bought and received a Paramount for my wife. The wheels are dirty and the chrome plated spokes are rusty. My first thought was to just relace the wheels with new stainless spokes, then the thought crossed my mind that if the aluminum, both anodized and not anodized were not affected by oxalic acid I could soak the wheels. Also of concern is the spoke nipples. Of course, I'd remove the axles and bearings, and probably grease the races.
Is this something I can or should try?
Thanks for your help!
I soaked a Peugeot 501 frame with an aluminum seatpost for several days and it didn't hurt the seatpost a bit, which is kind of a shame since I'm trying to get it unstuck! :mad:
Others have posted that OA will mess up anodized parts, and I know it will mess up the finish on galvanized steel.
That's all I got.
07-22-07, 02:24 PM
How many hours do you have to spare? This is the mother of all oxalic acid threads:
Started April 20, 2006, 24 pages long, people are still posting. And as it happens, in the last several posts, someone reports extensive pitting on aluminum rims after a soak. I'm sure there's more in the thread regarding oxalic acid and aluminum.
It will strip cadmium and zinc plating off of steel. It's kind of cool, you will see thousands of tiny bubbles coming off of the part that is soaking.
07-22-07, 06:30 PM
I was looking more closely at the wheels today, thinking how nice they would look with new stainless steel spokes and after the rims and hubs were polished. I am not sure it is worth the risk.
I do have a Weinmann rim like my wheelset that is bent beyond reuse. Maybe I will saw out a section and give it an extended soak. I also have a broken Campy hub I can do the same thing with. That might be the ticket before I destroy something worth keeping.
Old Fat Guy
07-22-07, 08:02 PM
A Google search of 'oxalic acid aluminum' yields some very detailed scientific results.
I'm not a scientist, but I think it may actually etch aluminum, and is useful as a prep for further coating. Perhaps a member who actually knows chemistry/metallurgy can read some of the articles and give us a conclusive answer.
My gut says that it is useful in removing rust(iron oxide), and since aluminum doesn't contain iron, oxalic acid is of little use on rims and the like unless one desires to use the acid to lightly etch the aluminum in preparation for another coating.
My gut is much like Stephen Colbert's, and is always right, unless one of you 'scientists' can prove it wrong.
07-22-07, 08:16 PM
I have tried old brake calipers and other aluminum parts in OA in the past with pretty good results. As I sit here, there is a Campy hub half soaking in OA out in my garage. I will leave it there for at least 24 hours and see what happens. Not to worry if it destroys the hub-it has a crack in it.
If the hub survives I will likely try it. If I do I will post before and after photos.
07-24-07, 03:37 PM
Here are the results of my test....
The Campy hub I soaked is cracked and the only reason I have it is to eventually use the remaining bearing cup. I soaked the drive side, without the cup, in OA for 24 hours.
Those little pits were caused by the OA, though the hub wasn't perfect before it went in the solution.
As it looked coming out of the solution:
As it looked after washing:
As it looked after a brief polishing with Blue Magic. Note the nice crack visible in this picture:
I tried to watch the etching progress, and there was very little etching after only a few hours in the solution which was pretty strong. If I soaked the whole wheel, I would definitely watch it closely and take it out as soon as possible.
I also put a spoke nipple in for a couple of days with no apparent harm done.
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