I might be shot down in flames by others but don't waste your money on a grout whitening pen. I have used one in the past & found it hopeless. I then discovered in a small bottle or another make in a tube something called 'grout whitener' one of which is made by Bostik. The stuff in the tube comes with a foam applicator but I couldn't get on with this so I applied it with a small paint brush. Basically, you apply it to the grout & don't worry about it touching the tiles! when dry in about two hours, you just damp down the tile & wipe of the excess with a cloth. It has transformed my bathroom & kitchen tiles. As far as I'm aware, its only available in white. You will not be disappointed if you buy it. You can get it in Wilko's on the section where the decorating stuff is & would cost you less than �4. good luck & hope this helps