Wall tile is generally used to cover the wall surface, but it can also be used to trim out different elements on the wall. If you have a wall that will have tile only over the bottom half of it, or that has wainscoting or another partial covering there, tiles can be lined up to form the border between the elements, in place of wood trim. Use bullnose tiles, which are finished on one edge, so that you can line up the finished edges to form the border.
Measure along the span where you want to put the edge tile, whether it is a standard tiled area or other material. Find and mark the halfway point.
Use a notched trowel to spread tile adhesive on the back of a bullnose trim tile, covering the whole surface to a depth of about 1/8 inch.
Press the tile to the wall at the centre line, next to the area it will border, with the finished side of the tile facing outward. Put two spacers next to the other side of the tile to separate it from the area it borders.
Set the other tile in place the same way, on both sides of the first one, building out from the centre toward the edges of the space. Set the tiles so their finished edges all line up and face out. Put spacers between the tiles.
Cut the final tiles on each end of the line, as necessary, on a tile cutter.
Let the tiles set overnight. Pull out the spacers.
Spread grout over all the tiles, using a grout float to press it between the tiles. Use a damp sponge to wipe off the excess grout from the tile face and the surrounding wall.
Some border tiles have built-in spacers.