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Cleaning VERY oxidized aluminum exterior?

Eiron Apr 20, 2013 10:39 AM

I couldn't resist.

I found an older All-Clad LTD (2qt?) saucepan at the thrift store.

The interior is in great shape, but the exterior is very oxidized from years of cleanings in an automatic dishwasher.

Before I break out the two tins of polishing paste & elbow grease, are there any tips and/or tricks to removing the oxidation easily?

 
 
 
  1. k
    kaleokahu Apr 20, 2013 09:39 PM

    Hi, Eiron:

    Good score!

    I have a fair number of aluminum pans at my beach house, and we occasionally have problems with saltwater corrosion of them (don't ask). What I do to clean them up is scour with a progression of grits of steel wool. I do it dry, but if you want to work vinegar into the mix, it won't hurt--maybe just decrease friction.

    I also have to ask: Are you sure what you're seeing as oxidation isn't just the contrast between the passivation layer where the anodizing is gone and the darker vestiges of anodizing? If this is what's afoot, you might save yourself trouble and just keep DWing it until all the anodizing is gone. Or, scour it away by hand.

    Aloha,
    Kaleo

    3 Replies
    1. re: kaleokahu
      g
      GH1618 Apr 21, 2013 10:17 AM

      That's an interesting idea. If this pan is actually LTD, it should be dark all over the exterior. In that case, how would the anodizing have been removed nearly completely?

      1. re: GH1618
        Eiron Apr 21, 2013 11:16 AM

        The pan appears to be LTD, as the bottom still shows the A-C script "LTD" marking. I guess I won't know if there's vestiges of anodizing until I try to clean off whatever's accumulated on it, right?

        I've never been attracted to new LTD pieces, but at the price this was going for, I thought, "Why not?"

        1. re: GH1618
          k
          kaleokahu Apr 21, 2013 08:16 PM

          I dunno, GH, but the photos just look to me like the darker anodizing is wearing away differentially. It might not be this at all, but then again, electrical currents and DWers being what they are, I wouldn't be surprised. Should be easy for Eiron to tell with a little scouring...

      2. Chemicalkinetics Apr 20, 2013 04:52 PM

        Let's say it is aluminum oxide. Aluminum oxide is more stable than iron oxides. As such, I am guessing that typical weaker acids won't do much. Because aluminum oxide is an amphoteric oxide, it can be dissolved by either acids or bases. See if you have any strong acids or strong bases. Be careful while working with them.

        5 Replies
        1. re: Chemicalkinetics
          k
          kagemusha49 Apr 20, 2013 07:17 PM

          Before you resort to strong chemicals (as it probably is NOT aluminum oxide) try the weak acid in vinegar first

          1. re: kagemusha49
            Chemicalkinetics Apr 20, 2013 07:41 PM

            No a bad point.

            1. re: Chemicalkinetics
              k
              kagemusha49 Apr 20, 2013 08:46 PM

              OK I'll retract my suggestion that the crud is NOT Aluminum oxide - but vinegar is still the best thing to try. Here are two links that support vinegar and other low-tech solutions
              1 http://www.howtocleanthings.com/surfaces/how-to-clean-aluminum.htm
              2 http://www.rd.com/home/20-ways-to-eas...
              I'd be really really careful around strong acids like hydrochloric or sulfuric acid - I occasionally use concentrated sulfuric acid on drains and take extreme caution when combining the acid with the water in the drain - lack of appropriate knowledge and technique can result in hot acid on bare skin and immediate charring. I'm a little more comfortable around strong alkalis but I'm not sure that that is rational of me.

              1. re: kagemusha49
                Eiron Apr 21, 2013 11:11 AM

                I have something called "Lime Buster" made with sulfamic & hydroxyacetic acids. I don't remember ever using it on anything, & I'm not sure why I bought it years ago. Compared to soaking the pot for an extended period in vinegar, is this something that might give a more immediate indication of whether or not the exterior is oxidized or just coated with deposits?

                1. re: Eiron
                  k
                  kagemusha49 Apr 21, 2013 11:21 AM

                  I've backed off my assertion that this cannot be oxidized. Still, many of these weak reagents work so slowly that it would be hard to identify any signs that would differentiate between various candidates. If Lime Buster is anything like CLR, it acts very slowly - OTOH I don't recall either of those acids being in CLR. "hydroxyacetic" acid is NOT acetic acid but is an acid often used in skin care products - not sure why it is in this product. Sulfamic acid is also an effective cleaning acid and is IMHO safer than either hydrochloric acid or sulfuric acid

        2. g
          GH1618 Apr 20, 2013 02:58 PM

          Soak it in white vinegar for several days, as a first step.

          1. k
            kagemusha49 Apr 20, 2013 02:52 PM

            It is almost surely NOT oxidation and much more likely to be a carbonate deposit or maybe a sulfate. I'd suggest immersing the exterior of the pan in vinegar - hot if necessary. I think this would work well and be a cheaper and more effective solution than using a commercial product like CLR.

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