I've tried rubbing with a citric acid paste (teaspoon of citric acid powder,
drops of water to make thick paste), scrubbing with a paper towel and my 10%
warm citric acid passivation solution, and soaking overnight with agitation
in the 10% solution, and had zero luck removing orange red Fe2O3 rust spots
or the blue to orange film from welding on 304SS. I would soak small pieces
of 304SS in salt water until I got rust when testing the passivation
procedure, then I tried to get rid of that rust and the welding scale from
beads across my test pieces, with zero luck. If you make it work, please
post how. Oxalic acid will, which is why I suggested BarKeepersFriend.
Wasn't sure it had abrasive, which is why I suggested testing in a
non-visible site. Under the handgrip would be good. Start by just dripping
some on and let it soak, you may not have to rub at all in which case the
abrasive won't matter. I guess I never tried citric acid on rusty mild
steel, so can't say if that works or not but my strong expectation is not.

-----
Regards,
Carl Ijames

wrote in message
...

On Monday, October 27, 2014 2:21:07 PM UTC-4, Carl Ijames wrote:
Unfortunately, citric acid doesn't remove rust. It would be a great last
step to repassivate everything after whatever else you do.

I am under the impression that citric acid does remove rust.


But one test is worth a thousand words. So I would recommend that you first
try citric acid on some ordinary rusty steel and see if you think it removes
rust. Then on some stainless with rust spots if you can find some.

You can find food grade citric acid at Tractor Supply. It is used to clean
stainless tubing in milking systems.

Dan