Floor tiles generally are covered with a protective glaze that repels stains and moisture. When you see a crack or chip in the tile, you'll need to not only fill in the damaged area, but also reseal the glaze, so it looks consistent with the surrounding floor and is protected from moisture. Epoxy glue is an excellent filler for chipped tiles, as it dries rock-hard and can be painted to the colour of the tile. Floor-grade polyurethane gloss with keep the paint from coming up.
Open the epoxy glue. If the glue come in two separate tubes that have to be mixed, mix them according to the instructions on the packaging.
Put a dab of the epoxy over the chipped area. Use the end of a toothpick to work it down into the fissure and smooth it along the top, so it's flat. Let the glue dry overnight.
Buff the dried epoxy very gently with extra-fine sandpaper, getting it completely smooth. Wipe away the dust.
Paint over the epoxy with paint the same colour as the tile, using a small paintbrush. Apply the paint only over the dried glue, not the surrounding tile. Let the paint dry for eight hours.
Brush a thin layer of polyurethane gloss onto the painted area. Let it dry to the touch. Lightly buff the polyurethane with extra-fine sandpaper. Apply a second layer of polyurethane. Let it dry overnight.