How to Prevent Paint On Ceramic Floor Tile from Chipping
When you paint ceramic floor tile, the best way to prevent chipping is to apply 2 to 3 coats of water-based urethane after the paint has cured for at least 3 days. This will give you a surface that can take the abuse of walking on the floor, and it will resist chipping from dropping objects on it. It will also make it water-resistant.
Avoid using oil-based urethane. It dries with a yellow tint and will cause your floor to take on an undesirable color. Water-based urethane will stay clear and will not effect the paint color.