Travertine mosaic, general questions...

[Diamond Pool Finishers]

not to sure about that film of gum over the back of the tile though mate!!IE second pic you posted!!! you need as much contact with the stone as poss mate and the film will prevent this, and may DE-laminate :yikes:

 

[DHTiling]

I would seal them after grouting..
Sealing them beforehand can seal the pores/holes and the grout will not take.

They will not stain with grout unless using a pigmented dark grout like black..

 

[averagejoe]

Thanks all, your advice has helped a lot. 🙂