bigneil

i did a job few years ago using cheepo B&Q 150x150 white tiles, and no matter what i did there was orange showing on a number of joints because the glaze on the tile finnished hard on the surface leaving a wee bit of the biscuit of the tile showing. i have never had this problem before or since. usually the glaze wraps round onto the edges, eliminating this enfuriating problem. Try re-grouting but dont wash the grout out so much. maybe a smaller hand sponge with rounded corners would be a better option than the big square one,...i usally only use those on flooring. also wait 20 mins or half an hour before washing so that the grout has a little time to stiffen in the joint so that not so much will wash out again.
I hope this is helpful