Aluminum kitchenware oxidized in sink?

Hello,

Sorry to bother you, however we have some very nice knifes with brushed aluminum handles. Recently while left in sink, the side facing down turned black and became pitted. What caused this? vinegar ⇦in bulk on eBay or Amazon [affil link] ? Bleach? Yogurt?
We've had them for years, and suddenly ... uggh!

Thank You for your time.

More likely an alkali like bleach, oven cleaner ⇦ on eBay or Amazon [affil link] , or Drano residue than vinegar or yogurt, Ed. I don't think there's much hope for the aluminum handles, unfortunately. But search the site for 'Dishwasher ruined aluminum' and try the cream of tartar or other solutions.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

See # 45202. If you rub long and hard enough, you can probably bring them mostly back.

If you really care for those knifes, you can use a rotary electric high speed tool similar to the ones used by hobbyists to grind, cut and polish (Dremel ⇦ on eBay or Amazon [affil link] or Black & Decker are just fine). Patience, care and a little theory of polishing will restore them. The later advises to start with the coarser grades of abrasives that will totally and effectively remove the damaged material leaving a continuous and sound surface (how coarse depends on how deep the pítts are). Then, down in successively finer grade steps alternating or crisscrossing every time the direction of cut to make sure all lines and marks left by the previous abrasive are gone. And so on until fine enough to give the pleasant look they had before or even better.