If you've got a ceramic tile wall or floor that is in good shape structurally but you don't like the color, you're not necessarily stuck with it. Despite their hard, nonabsorbent surface and glaze, ceramic tiles can be painted with the right preparation and follow-up. You need to dull the glaze enough to allow the paint to stick and then seal it in with polyurethane. When you're going darker, it will take more coats — at least four or five — but resist the urge to lay it on thickly, as that will make it more likely to peel off later.
Use the belt power sander and aluminum oxide belt to dull the surface of each tile. Move the sander in one direction over the tiles. Don't sand the grout. Continue until the tile doesn't sharply reflect light.
Wipe off the dust.
Brush on your primer-sealer in a thin, flat layer with the brushstrokes in a consistent direction. Don't paint the grout.
Let the primer set for 10 hours.
Brush your dark paint onto the tiles in a thin, light coat with the brushstrokes in a consistent direction. The primer will still show through, but don't try to cover it. Let the paint dry for 10 hours.
Apply a second coat of paint in the same manner. Let it dry for 10 hours. Apply subsequent coats as needed, keeping each of them thin and flat. Let the final coat set for 24 hours.
Use a paint brush to apply a coat of polyurethane, using the same process as you did with the paint, putting it on a thin, flat coat. Don't cover the grout.
Let the polyurethane dry for 10 hours. Buff it lightly with extra-fine sandpaper -- just enough to dull the gloss. Wipe off the dust.
Apply a second layer of polyurethane. Let it dry, lightly sand it and apply a third layer. Let the third layer dry for two days before using the floor.