The green marble floor in our bathroom is acquiring a specked white appearance that won’t clean off. What can I use to clean it?

First, you need to determine whether or not the white specks you describe are on the surface of the marble. If you can’t clean them off, chances are they lie below the surface of the marble. If this is the case, it is possible that there are dissolved salts in the marble—and should this condition persist, the marble will become pitted. Thoroughly drying the marble and then applying a silicone impregnator may help but the source of the salts must be found..

TIP Spalling of green marble is a common problem. In new installations it is important to apply a good silicone impregnator. Once spalling occurs it is difficult to stop.