I had a builder lay the tiles for me but i grouted them. I used black grout washed off the excess grout with a soft sponge and clean water and wiped off the haze with a soft cloth but some of the tiles have some very dull areas which appear as if the grout hasn't been cleaned off correctly, when it had been. Does anyone know how the dull areas have occured and what if anything i can do to correct it(bar replacing the tile itself)?
Thanks for any help or advice