Quick question

[Dan1234]

What is this white slightly powerderuly stuff on the back of the tiles and does it need removing before tiling or can you just lay the tiles.

Thank you

 

[White Room]

Give it a wipe over with a damp sponge if you have concerns.

 

[Tile Shop]

Its a backing glaze applied during manufacture to stop them sticking to the rollers while fired.

Any loose dusty residue can usually be brushed off by hand or damp sponge. Give the tile a back skim of adhesive, that'll stabalise it further, give you better coverage and better bond strength.