There are essentially only three things that can be done to remove the hardened grout from your wall or floor tiles.
Cleaning grout off slate tiles.
Use the grout haze remover and brush in a small typically 3 x 3 area.
Your grout is probably discolored by a gradual buildup of dirt and grime.
Scrub the surface of the slate tile with a generous amount of water and a nylon scrub sponge.
Safety tips tricks.
Use another clean sponge to rinse the scrubbed slate tiles with.
Porous tiles especially a stone such as slate need up to two or three applications of a special grout release.
The methods ahead outline how to remove grout haze using.
How to remove grout haze from a slate floor 1.
Don t worry you can bring back the brightness of the grout by using a 50 50 solution of water and hydrogen peroxide.
You may have to reapply the haze remover more than one time over certain areas as well as lightly scrape any large accumulations of dried grout.
Be careful if you have a slate floor with colored grout as this bleach solution could damage the color of that grout for tougher stains mix together peroxide and baking soda into a bubbly.
Try using a grout haze remover which is available at tile stores.
The thin set instructions say to sponge off any mortar from the tops of the tiles immediately or at least as soon as possible.
The cleaner alongside the brush and some good elbow grease should be able to take care of the unwanted grout on your slate tiles.
Work on three or four.
Scrape scratch and rub the grout off the tiles dissolve the grout without affecting the tile replace the tile s if you can t get the hardened grout off.
Pick up the dirty water with a clean grout sponge.
It s not always effective on slate however.
Tile and stone sealers will work sometimes but not always.
Water and cheesecloth a rubber grout float diluted vinegar on porcelain or ceramic tile only and a nylon scrub pad and a commercial grout haze remover.
If it doesn t work chances are the grout haze isn t removable.
Spray the solution on the grout and let it soak for about ten minutes.
Cleaning the slate is easy but now you have to clean that grout.