I foolishly asked tilers to do the grout in our new kitchen with the same dark grey they'd used with dark grey porcelain tiles in our hall. The kitchen tiles are a very light grey. They would have used white. I wish I'd asked them to mix white and the dark grey cos the finished grout is far too dominant - it's the first thing you see when you look at the tiling! Websites seem to suggest you can't lighten dark grout, only darken light grout. Have any of you guys done this successfully and if so, how? Thanks.