Q. How do I remove rust from a restaurant terrazzo floor?
A. I would try a liquid rust remover that contains Hydrofluoric or Oxalic acid which is often used to remove rust from terrazzo, tile floors, carpet and other surfaces. A cautionary warning: Hydrofluoric acid is very dangerous to work with and any acid will dull/etch the absorbent marble chips and cement base of terrazzo. Use great care using these products. Strip completely the spot, apply the rust remover, and within 5 minutes rinse. You may have to re-polish the area with diamond impregnated pads or discs.
A 12 inch floor machine or a hand held angle grinder will work best for this. If the acid product does not remove the rust spot, try Comet or a similar bleach-based abrasive powder. Dampen the spot, cover it with about 1/2 inch of bleach-based scouring powder. Cover with cardboard, apply a moderate weight and let it sit overnight. The next morning, clean the area. If either one of these steps works, re-apply finish or re-polish the area to bring back the shine.
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