I have recently put up some mosaic tiles in my kitchen and have grouted them. However when i have come to clean them, i cant get the grout out of the small indents in the tile. The tiles are about a inch square, they are also black and the grout is white,so it really shows up. I have tried a kitchen brush with warm water and a dry cloth but with no luck. I dont know what else to use, as i dont want to damage or take the shine off my tiles. Any ideas ?