After this initial drying period, remove excess grout with a damp, almost dry sponge. The object is to leave a hazy layer of grout over tiles, but leaving grout lines intact and even with the surface of the tiles. When dry (overnight) the tiles can be cleaned up, again using a damp sponge. Project can be sealed with a grout sealer if wanted, but is not necessary for these projects. I have used acrylic varnish (water based) and it appears to do a good job and leave a nice shine.