Re: HELP, and tilers out there?
There are tiles that are not sealed I had never seen them but a friend bought some without knowing and the grout color went into the tile. I have no idea if this is your problem or not I doubt that subway tiles are not sealed
I left tsp on once caused really bad adhesion. Didn't know any better. It does come off nicely after drying with bleach and water followed by a water rinse.