Cream of tartar?

[Christopher Nelson]

In the handyman column in this Sunday's paper, a reader solicited advice on getting stubborn stains out of a tub and the answer surprised me. The columnist advised the reader to wet the tub with hydrogen peroxide, sprinkle on cream of tartar, wait hours to overnight then scrub. It wasn't entirely clear if the reader had rust stains or other deposits. I haven't tried this yet and wonder how it's supposed to work. Does anyone understand the chemistry of this process? Or is it just bunk?

[John Q. Public II]

I don't know the science behind it, but I found lot's of references to this method:

Here's just two:

Cream of tartar, a mild acid, may be mixed with water to form a paste rust remover.

Stains: Brown, black or others (from manganese and other minerals)

Paste made of cream of tartar and hydrogen peroxide; let stand, then rinse

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Tub scrubber

Let this simple solution of cream of tartar and hydrogen peroxide do the hard work of removing a bathtub stain for you. Fill a small, shallow cup or dish with cream of tartar and add hydrogen peroxide drop by drop until you have a thick paste. Apply to the stain and let it dry. When you remove the dried paste, you'll find that the stain is gone too.

[Richard J Kinch]

Tartaric acid is a very expensive source of protons.

Just buy some CLR, or better, the Zep brand at Home Depot.