Apply the Grout
Remove tile spacers. Remove any excess mortar that sticks up between the tiles with a utility knife. Mix the grout according to manufacturer's directions. Mix only one bag at a time to keep color and thickness as consistent as possible. Dump out approximately one-third to one-half of the mixture onto the tiles. When tiling a large area, it is best to tile, grout and sponge in manageable sections. Use a hard rubber float to pack the joints, pulling the float diagonally across the tiles. When the tiles are grouted, begin to clean away excess grout. Use a large damp sponge to wipe across the tiles in a diagonal line to keep from pulling the grout out of the joints. Rinse the sponge repeatedly until the process is done.