Removing Metal stains

[waterbear]

Thanks for the reply. I assume you mean oxalic acid, not ascorbic acid ?

Marty

yep, blonde momemt! (I refuse to say senior moment!)
All three will remove some, but not all metal stains (some copper stains are just about impossible to remove).
Ascorbic acid is the safests but the most expensive and it's price has gone up a lot lately. Oxalic acid is the least expenisce and is found in some commercial products such as United Chemical's Pool Stain Treat but is it very toxic and somewhat corrosive. Citric acid is just slightly more expensive than oxalic acid and is much more benign but still more irritating than ascorbic acid but not considered a poison.