Coat the entire counter with the specially designed adhesive, which is available at home centers and tile stores. You can apply a liberal amount, then create grooves in the adhesive using a notched trowel. The notches aid with adhesion the same way similar notches create a strong bond between thinset mortar and tiles.
Preparing the surface for tiles is a two-step process. In the second step, lay a sheet of fiberglass backing into the adhesive. The fiberglass backing is similar to the tape used for hiding drywall seams, except that it is sold in wide rolls. Remove air bubbles that mar a smooth surface by pressing the fiberglass into the adhesive.
Once the adhesive dries, a thin coat of mortar helps even out any blemishes left by the first steps. This thin coat is also called a skim coat, and it’s made with thinset mortar -- the same product used to set tiles. The skim coat acts as a sort of primer that strengthens the bond between tiles and the existing counter. When the skim coat dries, trowel on more thinset and comb it with a notched trowel.
Set porcelain tiles into the freshly combed thinset. Give the tiles a slight twist so they grip the mortar. Some installers prefer setting bullnose tiles first. Those are the tiles that go along the edge of the counter. Other installers worry that they might skew those tiles out of position when reaching across the counter to set tiles flat on the counter surface. Establish joint lines by placing spacers between tiles.
Grout is the finishing touch to any tile job. This mortarlike material fills the gaps, or joints, between tiles. Hold the grout float at an angle so you can force the grout into each joint. Sweep the float and grout across tiles at an angle. Pushing the grout and float directly square to joints pulls grout material out of the gaps. Finish tiling by cleaning the tile surface with damp sponges and fresh, clean water.