Materials: cleaner
sponges
sealer
buckets
grout
grout float
margin float
Grouting
1. Because slate is porous, prior to grouting the tile needs to be cleaned and sealed so the grout doesn't leave a film on the surface.
2. Apply cleaner, just spray it on and wipe it off with a sponge (figure A).
3. Pour sealer in bucket and wipe on with a sponge (figure B).
4. Follow manufacturer's instructions to mix grout. Use a trowel and do it by hand instead of a mixing bit which adds air that can weaken the life of the grout.
5. With natural stone you don't want to use an admixture as it will stain the stone.
6. Put grout in intersection (figure C). Spread with grout float at a 45 degree angle, making sure all the seams are filled in.
7. Sponge excess grout off the tile. Wipe aggressively in the center of the tile, but gingerly near the grout lines (figure D).