For what it's worth, my mom used a wire brush on the bathroom sink in my childhood home (build around 1920). She then painted the underside white with a paint similar to rustoleum (not a spray paint). Tape off the visible part of the sink well, you don't want to get paint on it. The sink lasted a good 30 years more.

I'm not sure that this is the correct way to fix the problem, but you have nothing to lose by trying, right?

Hope this helps. LOL

Homemaker- Thanks for your advice! If a little elbow grease can lead to another 30 years I'm ready to give it a try. Even the burley plumber who removed the sink encouraged us to keep it ( except for the 1970s construction grade faucet)---of course he didn't see it before I started cleaning, scrubbing and pumicing.

kim, this is a surprisingly common thing but is usually done on cast iron claw foot tubs. The industrial solution to this problem is sandblasting. I re-did my clawfoot tub with a palm sander followed by steel wool and a gloss white rust paint. Looks tremendous! Good project for you, and good luck!

Beds, Great suggestion! This will be the first of 2 sinks so it'll be good to try it out. Did you do the whole tub on the top side as well as the underside? I ask because I've got an old, small clawfoot tub that's waiting out in the shed for some attention and I had no idea that it might be possible to refinish it myself. Any specific recommendations on paint brand? I might have to become a "diy"er yet. LOL.