The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Oxalic Acid cleaning of old anodized aluminum.

Hello All, Long time reader, first time poster. Thank you all for your feedback in advance.

I have a 1964 Avion Travel Trailer (like Airstream) that has an anodized aluminum skin that has become oxidized and chalky white with age. (Yes, unlike Airstream, Avion trailers were anodized for my year production.)

I have tried and or/researched numerous solutions recommended elsewhere that others report have varying success...including wd-40, par-fe wax, everbrite, bon-ami, polishing compound, bronze wool+mineral spirits, and clearcoating, but none seem to be the 'miracle cure' I am seeking (if such a cure exists.)

What seems to have worked the best thus far is a product called CLR metal shine, which has the primary ingredient of oxalic acid.

The Question: since the aluminum was likely anodized in the first place with oxalic acid (plus current and temperature), would cleaning it with oxalic acid do more damage than good? Looking at the test area, there is a marked improvement to the look, but I would hate to 'molecularly' damage the aluminum to the extent that it would be even more prone to corrosion over the next 50 years.

FYI, I don't really care if some of the anodized coating is stripped in the process, as it serves primarily a cosmetic purpose...and since the anodized coating looks poor, it doesn't necessarily serve a purpose in that regard.

Hark H
car restorer - San Ramon, California
August 24, 2011

Try 5% ammonium citrate solution,pH must be corrected to 7(50 gms citric acid ⇦ this on eBay or Amazon [affil links] /1 lit water +add some ammonia,until pH value is 7 .Oxalic acid is toxic.Try to avoid any contact with solution,use rubber gloves!Hope it helps and good luck!

Goran Budija
- Cerovski vrh Croatia
August 28, 2011