How to Replace Curved Border Tiles

Install the appropriate blade on your grout saw -- the toothed blade works best for sanded grout and large grout lines, while the straight blade works best for unsanded or small grout lines.

File the grout lines with the grout saw until absolutely no grout remains. Go slowly, and don't scratch the surrounding tiles with the blade. Continue filing until the curved tiles are completely free of grout on all sides.

Pry the tiles loose with a chisel or large flat-head screwdriver. If they don't budge, tap them with a hammer to break them and loosen the mastic.

Chisel away any mastic that remains on the substrate -- the surface must be completely flat or the new tile won't lay properly. Scrape the edges of the remaining tiles with a screwdriver to remove bits of stuck-on grout and mortar.

Dust the area with a large dry paintbrush, removing all crumbs and bits of broken tile. The cleaner you can get the area, the neater the finished product will look.

Apply mastic to the area to be tiled, spreading a thin even coat. Apply more mastic with the toothed side of the trowel.

Apply a small amount of mastic to the back of each tile, and lay it in place. Use appropriately sized tile spacers if the tiles are not self-spacing. Once all the tiles are in place, tamp them down with a clean grout float to ensure uniformity. Allow the area to dry overnight.

Spread grout over the new tiles, pressing it into the spaces between tiles with the grout float, then scrape off the excess with the float held at an angle. Overlap the existing grout on the remaining tiles just a bit. Allow the grout to dry for 15 minutes.

Wipe the area with a slightly damp sponge to remove grout from the surface of the tiles, wait 15 minutes, and then wipe it again. This time, wipe each grout line individually, feathering the ends over the existing grout. Allow the area to dry overnight.

Dust the area with cheesecloth to remove the grout haze, and apply grout sealer according to package directions.