What grout for slate tiles?

[caperskmt]

Hi
We are planning to tile the new extension with slate and have got the adhesive etc all sorted out. What do most people use for grouting slate (indoor) and it is going to be sealed afterwards. Is mortar the best option? and what mix?

Thanks
caperskmt

[Planned LScape]

I wouldn't use mortar for grouting, it has brick sand which has a lot of clay and can shrink

Either buy a pre-mixed tile grout or if mixing yourself use a sloppy 3:1 fine washed sand: off white cement mix. Keep the tiles wet to aid moving it around, it can also make things very easy if you pre-seal the slate careful not to get any in the joints so that the grout wont get caught in the depressions in the slate tops