It's outside an entrance but by the look of it they exactly the same tiles as they have used inside Builder have left it like this and customer is going ape about it. It's killed me day off trying to get rid of these stains am just in way for hypo now
It is wot it is Samson !!! I just put hypo all over it 1/3 mix al leave it on an hour an scrub it off if no joy I will go get some solvent cleaner but don't really want to incase it leaves marks