Pumice stone is used to soften rough skin around the feet and elbows; no one would think of pumice stone as a rust cleaner.
I learned of the use of pumice stone as a ceramic cleaner online. It worked to remove calcium and lime stains around toilet and bath tub. This worked so well, that it restored these items beautifully. I wondered if this would work on other surfaces, and to my amazement, it did. I tried using pumice stone on some vinyl tile flooring that had some rust stains from a file cabinent . I wet the floor with water and the pumice stone and gently rubbed the stone on the rust stain area. Just gently rub the stone not to scratch the tile; the stone disengrates slightly and leaves grainy residue. As the stain is removed take wet cloth and cleanup the dissolved residue. The floor looks rejuvenated and restored. Next, I plan to use it on porcelain tile as well. Pumice stone is a great inexpensive rust, calcium and lime cleaner.
