Cast Iron stained by acid

[Andrew Barss]

A person put an empty bottle of concrete acid stain on my tablesaw, and the resisue on the bottle dripped and stained the top. The stuff contains chromic acid and hysrochloric acid. The metal isn't etched, but a very dark brown/black. Is there any way to remove this stain? I'm unfamiliar with the effects of acid on metal.

Thanks,

Andy Barss

[John Grossbohlin]

I don't know that you could remove the stain but I would neutralize the acid by dissolving baking soda in water and put it on the table surface. Keep it wet and let it soak into the iron for a while... wipe it off and soak it down with WD40 to drive the water out. Let both the soda water and WD40 soak in good as cast iron is rather porous. Wipe off the residue, let it dry, wax, and let it go at that.... That acid stain could be pretty deep into the iron and trying to get it out with abrasives could very well leave a hollow in your saw top,

John

[Leon]

I have my hand print stain on my TS...I have learned to live with it....I went with steel wool and WD40 but did not want to risk "diggin in" for the sake of looks.

[Tim Foecke]

Hydrochloric and chromic acids don't eat cast iron. The residue is likely a ferrochromate. Hit it with baking soda to neutralize, then scrub with SOS or fine sandpaper. There should be no pits.