Recently we were asked to resolve an unusual problem with Limescale deposits on Black Slate floor tiles installed in a WC at a house in Hove on the East Sussex coast. You can see from the photograph below how Limescale has left an unsightly white haze and water marks on the surface of the slate tile.
Cleaning Limescale from a Slate Tiled Floor
The first step was to remove the Limescale and any other sealer products from the floor using a strong dilution of Tile Doctor Pro-Clean scrubbed into the floor using a rotary machine fitted with a black pad, we also used a stiff brush along the grout lines and in those hard to reach areas around the toilet. The floor was then rinsed thoroughly with clean water and any stubborn areas revisited with a repeat of the same process until we were happy the tiles were clean. Had the Limescale proved harder to shift we would applied a stronger product such as Tile Doctor Grout Clean-Up which can remove mineral deposits.
Sealing Black Slate Floor Tiles
We left the floor to dry overnight and came back the next day to seal it using Tile Doctor Seal and Go, a highly recommended sealer for Slate which provides good stain protection with a low sheen finish, slate is quite porous and it took five coats before it was fully sealed.
I think you will agree the slate tiled floor looks transformed as well as being much easier to clean.
Source: Cleaning and sealing Slate floor tiles in East Sussex