Drill Holes in Ceramic Tile
DEAR TIM: How do I drill holes in ceramic tiles? Are there special drill bits for ceramic tile? What is the worst thing that can go wrong? Lawrence Fefergrad, Montreal, Canada
DEAR LAWRENCE: The composition of ceramic tiles is as different as there are countries in the world. For this reason, there is no one single answer on how to drill a hole in ceramic tile. There is, however, one drill bit that indeed will go through each and every tile, but you may have great difficulty locating it.
Many ceramic tiles have a fairly soft inner core and a thin hard glaze on the outer surface that you look at. These are the very easy to drill through. The easiest tiles to drill into are very soft tiles that are often found in homes built in the southwestern part of the USA. Frequently these have no glaze or a very thin satin finish.
Tile hardness is a function of the type of clay and its silica content used to make the tile. The final hardness of the tile is also directly related to the amount of time the tile is in the firing kiln and the temperature inside the kiln. High temperature and long baking times can produce rock-hard tile.
Glass and porcelain tiles are very popular right now. These products are the hardest tiles to drill into. You can use a sharp carbide drill, but you need to oil or water the bit to keep it cool as it rotates on the tile. A diamond-encrusted bit will drill into porcelain or glass faster than carbide, but these bits are expensive.
If you are drilling into softer tile, a regular carbide bit works fine. Do not use a hammer drill as the rapid vibrations can crack the tile. The trick is to use a slow drilling speed and carefully grind through the surface of the thin glaze. Once the bit gets into the softer core, the drill will rapidly cut through the softer fired clay.
Do not apply too much pressure when you first drill as the drill and bit can slip away from the marked point and scratch the tile. The worst mistakes you can make are cracking or scratching a tile. If that happens, it will be a considerable amount of work to replace the damaged tile(s). Be careful and proceed slowly as you drill.