On May 26, 4:08*pm, " wrote:
My bathtub has a stain in it that is impossible to remove so far. Here
is a picture of it:http://www.flickr.com/photos/5423000...7629878927850/.

What should I use to remove the stain? I tried bleach and it does not
work. It feels rather rough and even powderly at the stained area.

Thanks

Whink, mild HF acid

WEAR GLOVES!!!! Else the tiny bit that gets under your nails you'll
pay dearly for, ...after about an hour, then feel the pain for days.

You can also 'try' Dial Liquid antibacterial handsoap - the thick gold
color. Put on a paper towel [the liquid onto the towel, not YOU
putting on the towel] and rub into the stain area. We found that the
product sometimes removes/reverts rusted tools and metal damage back
to new like shine.

May be more difficult for you to get [may be available at janitorial
suppliers, Unicide 256 by Brulins, Indiana. It's a quaternary compound
in the form of a sanitizing liquid for use around people and pets -
hospitals, veterinarian clinics, etc. The product is supposed to be
cut 256:1, so that a gallon makes 256 gallons of bleach-like killing
power. But my wife found that at 16 to 20:1 it 'returns' metal.
Example, rusted chrome plated vacuum cleaner tube. Tube was rough and
reddish powdery and came off on everything, essentially became a trash
tube. Wipe with unicide solution and the rust ALL disappeared, the
chrome shine came back, and all that was noticeable were tiny little
pin-prick like holes over the surface [pitting], but the tube no
longer turned your hands red and at a distance looked new. Example 2:
finally discovered our lost pair of Krauter pliers had been left
outside for one year! Rust beyond belief, would not even open/close,
absolutely rigid. After soaking in solution and then rubbing surfaces
to polish, regained pliers. However, as expected the pliers were
permanently roughened, but at least finish was stable and after
oiling, the pliers were as good as new, didn't even notice any 'play'
in the box joint.