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?

Christopher Nelson wrote:
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?

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

Here's just two:

From the NC State University College of Agriculture and Life Sciences:

http://www.ces.ncsu.edu/depts/fcs/ho...bs/fcs397.html

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

******************************

From Readers Digest:

http://www.rd.com/content/openConten...ontentId=23827


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.

Christopher Nelson writes:

Does anyone understand the chemistry of this process?

Tartaric acid is a very expensive source of protons.

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