Mix black tint into the primer to make a color that resembles grout. Tape around the perimeter of the area to be faux finished with 2-inch wide low-tack painters tape. Paint around the edges with the brush. Fill in the rest of the area with the paint roller. Allow the primer to dry for at least 24 hours.
Use a tape measure and pencil to mark out an even grid for the faux ceramic tiles. Place strips of ¼ inch tape in between the squares of the grid to make a faux grout line when the tape is later removed.
Paint the entire surface with paint in a color that resembles terracotta. Use either a brush or a roller, depending on the size of the surface. Apply two coats of paint for full coverage.
Mix latex glazing medium with tints. Glaze should be slightly lighter of darker than the terracotta paint, depending on your preference. Use burnt sienna tint mixed with a little bit of black tint to make a darker glaze. Mix white tint with burnt sienna tint to make a lighter glaze.
Brush the glaze on in sections of approximately four tiles. Create a mottled effect by dabbing and rubbing the surface with bunches of rags. Glaze the entire surface, applying and distressing each area before continuing on to the next section. Allow the glaze to dry overnight before removing the tape.