Black grout staining

[Graham duff]

Hi, I have recently tiled a bathroom in a 9mm glazed Pietra serena lev 60x30 polished porcelain tile. I used a black bostik technik TGS grout but unfortunately it has left behind staining that I cannot remove, I have used HG cement grout film remover and vinegar but to no avail, I can’t seem to shift it, what exactly would remove this dye staining from the tiles, the last thing I would want to do is to completely cover the tiles in grout to match existing staining or have to remove the tiles completely and start again, any ideas would be really appreciated, thanks so much

 

[Glynn]

Contact Lithofin Bob. The Guru of tile sealers and cleaners.

 

[Anthony]

Had this problem myself some polished tiles need sealing.most come already sealed but in my case factory hadn’t done it ( bad batch) so tiles are effectively porous. Your not going to get that out.try grouting over whole face so it’s all uniformed at least. Failing that start again. Disheartening to say the least