Removing Water Ring Stain from Cast Iron?

How do I remove a water ring stain from the top on my table saw?

How do I remove a water ring stain from the top on my table saw? Someone left a soda can, then they put a board over it so I did not see it. Help! – Ed McMahon, Jr.

Chris Marshall: Ed, as you can guess, you've got two goals here. One is to remove that rust ring, and the second is to try to avoid scratching the cast-iron as much as possible. Here's what I'd do: I'd use 000 or 0000 steel wool, or a comparable synthetic scrub pad lubricated with some mineral spirits, and rub off the rust. Sounds like the amount of rust is pretty light – more of a surface stain than hard-core rust damage from long-term neglect. If your saw table shows a milling pattern in the metal, I'd try to rub in the same direction to make the scratches less noticeable. Then, of course, coat your saw table with paste wax and buff it out, or use a dry lubricant instead to help seal the metal and prevent these water rings from happening again.

Tim Inman: Removing stains from cast iron is virtually impossible. Abrasion – sandpaper – is the only successful method I've ever found. Any chemical treatment that would remove the stain will just leave behind its own marks. Actually, once the "shiny new" has worn away from my recent acquisitions, I seldom ever repolish my cast-iron tops in an effort to make them or keep them looking like new. Mine are old and show the marks of age and use. I do keep my tops bright and clean – and waxed! – so they are slick and useful. But alas, you're probably stuck with a mark.