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Drilling into glass mosaic tile

user-6325848's picture

Can anyone offer tips or advice on drilling into installed glass mosaic tile?  I'll be hanging mirrors on screws inserted into the drill work.  If I drill into the tile, is it possible that a crack in one small piece will travel far and wide?  Also, should I use a diamond drill bit?  Masonry?

carbide (post #214676, reply #1 of 2)

First, if you can drill into a grout line instead of the glass, go that route. It's much easier.

Drilling glass tile can be tricky. Drilling a smaller mosaic glass tile? More difficult.

There are carbide tipped and diamond coated bits for drilling glass. They do a fine job.

Apply even but consistent pressure. Keep the bit perpendicular to the surface of the tile.

If you tilt the drill and catch an edge, crack. That can be more common with carbide. If you slog too slowly and let heat build up, crack. Heat build up can be more common with diamond bits. If you press to hard, crack.

If there is full thinset coverage behind the tile, that can improve your odds as the tile will be fully bonded with full support. Any thinset voilds can increase the liklihood of cracking.

When a small mosaic cracks, the crack will typically propogate through the width of the mosaic. Might even pop bits of the tile out.


There are 10 kinds of people in this world; those who understand binary and those who do not.


You need a special drill bit and lots of patience (post #214676, reply #2 of 2)

I've done this kind of work. Purchase a special drill bit designed specifcally for glass. It has a wedge-shaped tip and does not look like conventional drill bits. Drill slowly, lubricating as you go along. Roto Zip, Dremel, Bosch and others offer such drill bits with lubricant. It takes time to drill a hole.  The work is made easier if you drill into a grout line, but this is not necessary. Make sure the hole you drill is larger than the wall anchor/shield that holds the mirror. This is very important, because even a small amount of pressure can cause the glass tile to crack. Flunctuations in room temp. affect the glass tile. DO NOT DEPEND ON THE GLASS TILE TO HOLD THE MIRROR. The tile backer/drywall/substrate will do that. And...uh...don't be fazed by a broken tile. I suggest you drill and insert the (plastic) anchors and test the system 24hrs BEFORE you grout. It is far easier to do repair work sans grout. But if you must repair after having grouted, you MUST remove the grout around the offending tile, else you risk breaking surrounding tiles.

Mel Fros froscarpentry.com