Before you grout travertine tile, decide whether you want the holes grouted along with the lines between the tiles. Leaving the natural holes will make the stone look more natural, but grouting is more tedious than if the whole tile, lines and holes, are grouted. In either case, a sealer is applied to the areas not to be grouted, and then the grouting is done. After the grout has dried, another coat of sealer is applied over everything.
Grouting Everything Is the Easy Way
If it is desired to fill the holes along with the grout lines between the tiles, things are much simpler, but the result will not be as natural looking. Grout in a darker color can be chosen to fill the holes and lines for contrast. This will darken the overall color off the travertine tile, but the natural look of the holes will remain, and the holes will be filled. If a matching grout is used, it just won't look like travertine. First, prepare the surface according to the instructions in the sealer and the grout. Apply a natural stone sealer according to the instructions on the sealer label. Apply sealer only on the flat surface of the tile, not inside the holes or the sides of the tile, because this is where the grout will need to go. After the sealer has dried the proper amount of time, mix the grout and apply a large gob on the floor. Using a gout float spread the grout all over the surface, pressing and forcing the grout into the holes and lines of the tile. Let the grout sit for the required time, and then wipe down with a damp sponge to remove the excess grout on the sealed area. After letting the grout dry for a couple of days, apply more sealant over the entire area and let dry the proper amount of time.
Leaving the Holes Unfilled for Natural Beauty
If you have the time and the patience, you can get a more natural looking result by just grouting between the tiles and leaving the holes unfilled. After preparing the surface, as needed by the sealer and the grout label directions, use a brush to apply sealer to the tile surface, avoiding the sides of the tile. Make sure the sealer goes into the small holes in the tile but does not fill them. When the sealer is adequately dry, mix the grout and apply it between the tiles at the grout lines with either a four-inch putty knife or a grout bag. Run the grout float along the grout lines, avoiding the holes in the surface of the tile. Wipe the grout out of the holes immediately if any gets in. Allow the grout to dry, again consulting the grout label for the required drying time. Wipe down the grout lines with a damp sponge to remove the excess grout, allow to dry, and reseal the entire surface with sealer, and let dry.