Slate is a metamorphic stone made of several layers of compressed mud. It has a naturally cleft surface that can be ground down to a smooth, honed finish or left in its natural state. Some slate tiles are much softer than others and may scratch if furniture or heavy objects are dragged across them. Depending on the type and finish of the slate, it may be possible to cover these scratches.
Cleft Slate and Tile Enhancers
Cleft slate is naturally chalky and dull in colour when first installed. It is recommended that the slate be sealed with an enhancer to remove and hide this chalky finish. Tile enhancers can also temporarily darken the area around a scratch in cleft tile, helping the scratch blend in with the natural clefts, grooves and dents found in the surface of the tile. Tile enhancers do wear off over time, however, because they stay on the surface of the stone. Therefore, the hidden scratch will reappear again once the enhancer has dulled or been partially washed away.
Honed Slate and Tile Enhancers
Honed slate has been ground to a smooth, flat finish that is unfortunately extremely prone to scratches. Because the surface of the tile is smooth, with no clefts or grooves, these scratches stand out more and are more visible than they are on cleft slate tiles. Tile enhancers are not typically used on honed slate tiles because these tiles do not spall, or become flaky and dusty after installation. The enhancer would not deepen the colour or truly enhance the tile in any way. Therefore, tile enhancer placed on a honed slate tile would do little, if anything, to hide a scratch.
Hiding Scratches in Cleft Slate
If a temporary fix is not sufficient and the scratch continues to show up after a tile enhancer has been tried on a cleft slate tile, it is possible to continue to reapply the enhancer to the tile. This will continue to darken the slate and give it a slightly "wet" look.
If this method or appearance is not desired, the scratch can be also be masked by an application of linseed oil. The oil will penetrate the tile more deeply than the enhancer and create a longer-lasting mask for the scratch so it blends in better with the tile and remains hidden.
Removing Scratches From Honed Slate
If the honed slate is extremely scratched and you do not care for its finish, the only way to remove the scratch is to rehone the tile. This can be done at home with honing pads and a buffing tool for small or shallow scratches. Fit a honing pad to the tool and buff lightly in circles until the scratches are diminished. If the scratches are deep or if they cover multiple tiles or areas of the slate, have the floor refinished by a professional. He will grind down the entire installation at once to remove the deep scratches and give the slate a uniform appearance once again.