If you have slate tiles on your floor and they have lost their shine, don't give up. Even if they are cheap, there are a couple of easy fixes that can make all the difference.
Type of Cleaner
Clean slate tiles will have a natural shine, so before using a product specially for creating shine, just give your slate a good scrubbing. The best cleaners for slate tiles are ones that have no acid in them as do lemon juice, vinegar, and ammonia. Don't use any multi-purpose cleaner that contains these elements or it will etch the surface of your tile and make it dull. It is very difficult to restore the shine to an etched tile floor, so if you have done this already, replacing it may be your only option. You can try to repair some of the damage anyway with cleaning before you proceed further.
Instead, opt for a mild household cleaner, perhaps with an alkaline base since this is safe to use on slate. Simply mix the amount recommended on the label of the product in warm water and mop as you would any floor. You may want to towel or rag dry the floor to prevent streaks that air drying may cause. If you see streaks, try rinsing with clear water only.
Slate tiles originate from a number of places around the world, whether they are cheap or expensive, and as such, they can take different methods of cleaning depending on the type. Before cleaning the entire floor, test the surface to be sure that you are not dealing with any special finishes that may discolor the tile.
Shining Slate Tiles
Rinse your tile surface thoroughly with warm water to be sure all residue of soap is gone. Then, apply a cleaner-shiner product such as Mop & Glo or Orange Glo to the tiles per manufacturer’s instructions. This will temporarily fill scratches and restore a luster to the floor, but will need to be repeated after each cleaning.
You can also apply certain kinds of sealers to slate tile to get a more defined finish. Two main options exist, but the one you will want to use for a glossy finish is topical sealer. This type has a life expectancy of about three years, after which the slate will need to be stripped of what remains, and be cleaned and resealed.