Residue from gftk left on limestone slabs - pics!

[exdirectory]

I have installed gftk 2-part vdw815 which has gone down well and looks good. However, as the tiles dried after being wet there is a quite a large amount of residue left on the tiles - especially near the edges - a picture frame effect. I spoke to NCC who said I didn't use enough water and so the product was not free flowing enough - essentially as I was pushed it around with a squegee it was leaving glue residue on the tiles.

Does anyone have any suggestions for removing the cured residue, someone mentioned petrol was good for hardened glue. Obviously I will use a test piece first but any other ideas??

Picture here

So disheartening to have done all the hard work and for a poor result!

[London Stone Paving]

That's a shame. I assume that its black limestone and if so be really careful about what chemicals you use on it. Black limestone is HYPER sensitive to anything acid based. I certainly wouldn't consider using petrol. Its probably not what you want to hear but time is your friend here. the residue will slowly go but it will take a good few months