honestly, you cant.. I had the same problem, went too fast and grout dried on. I had done some 1st time tiling in other tiles, and not done slate before. Once it's dried you knackered. you can try...
That's rough, I have used detergent 9000, its an acid ,if you use it wear resporator,if its not that bad you can use a puddy knife, brilo pad ,or a scotch btight pad, always try a small area to see...
Grout residue can be removed with commercial products available at home centers and hardware stores. The grout removers generally contain an acid which reacts with the lime in the grout cement,...
Even though you can use a chemical cleaner to clean your shower tile, I have found that one of the best method for cleaning til and grout is to use a steam cleaner. Steam cleaners are much faster and...