Drilling clean holes through glass tiles is a difficult task even for seasoned DIYers. Glass is an extremely brittle material that cracks easily under pressure. Professional tile installer, Craig Cahoon, explains in his step-by-step tutorial that achieving clean, precise holes requires specialized drill bits, thoughtful preparation, and careful technique. Understanding glass tile drilling will give you the confidence to incorporate this striking material into your next tiling project.

Choosing the Diamond-Tipped Drill Bit

When drilling clean holes into tiles and glass, it’s essential to use drill bits that are considerably harder than the materials being drilled. Bits tipped with diamonds are designed for this job. They have a durable diamond grit edge that is significantly harder than regular drill bits. When comparing drill bit types, remember diamonds are ranked higher on the hardness scale than other abrasives, like carbide. Diamond edges stay sharp for longer than other varieties, increasing their quality and lifespan.

When picking a diamond-tipped bit, choose one specifically made for glass. The bits for glass have a shaft with channels for liquid lubricant. These bits also have smaller, finer diamonds to make precise cuts. The specialty glass bits will work much better on glass tile than those intended for stone or ceramic.

Adjusting Techniques Based on Glass Tile Type

1. Tempered glass is treated with extreme heat for increased strength, making it denser and more difficult to penetrate. Maintain very gradual pressure and reduced drill speeds. Too much pressure or force can shatter tempered glass unexpectedly.

2. Frosted glass obscures visibility, requiring careful prep to pinpoint hole placement. Opaque finishes also lack the slick face that allows lubricants to spread readily. Apply extra lubricant so it penetrates the frosted texture.

3. Colored glass often contains more minerals, translating to increased hardness. Adjust pressure accordingly and regularly clear glass dust from the bit

Effect of Glass Thickness and Hardness

Thicker glass requires more work to penetrate. Not only must the drill cut deeper, but the increased friction also amplifies heating risks. When drilling clean holes over 1⁄4 inch thick, reduce speed, apply more lubricant, and drill clean holes in increments.

Hardness has a proportional relationship to required drilling pressure, more PSI is needed for tougher glasses. Don’t force it, let diamonds handle the hardness gradually.

Unique glass types impact the practical approach. Once you understand how properties of materials like temper, color, frost, thickness, and hardness influence the process, you can adjust factors like speed, lubrication, and pressure accordingly.

3 Steps for Preparing the Work Area

Step 1: Before drilling into an uninstalled glass mosaic tile, apply painter’s tape over the area to prevent the drill bit from slipping around, minimizing edge chipping. Chipping often occurs when you begin drilling this brittle material if not properly secured.

Step 2: Place the tile on an MDF board or plywood to provide backing support. Ensure the surface below this backing material is solid and stable. Plumber’s putty or Blu Tack can temporarily adhere the tile to the smooth surface of the wood, preventing it from shifting during drilling.

Step 3: Mark the center of the clean hole at the desired hole location with a permanent marker. Making a guide indent with the drill bit on a low setting first can also prevent slippage.

Mastering the Glass Tile Drilling Technique

The key to cleanly drilling clean holes in glass tile is employing a slow speed with mild, consistent pressure. High speeds generate friction and heat that can fracture the glass.

Start drilling at a 45-degree angle on a low setting. Once the drilled diamond edge bites into the tile, straighten the drill to a 90-degree position. Maintain a firm but gentle pressure while drilling slowly through the glass.

Lubricating the entry point and drill bit shaft is imperative when working with glass to prevent overheating. An air tool oil or silicone works well for the job. Reapply frequently.

Expect some resistance and popping sounds when drilling through glass. Reduce speed if resistance increases to avoid cracking but do not detach the drill. Diamonds are grinding through this hard material. Patience and persistence deliver clean results.

Special Considerations for Installed Tiles

Drilling installed glass mosaic tiles requires an adjusted approach. Here, a variable-speed cordless drill provides optimal control. Corded drills with speeds locked in high gears strain precision.

Begin by mapping drill locations and placing small pieces of masking tape over each in an X pattern. Use a center punch or carbide scribing tool to lightly indent each spot, preventing the drill from skating across the slippery tile. Remove any grout residue to expose the tile surface.

With your entry points marked and secured, drill using the same slow, steady, lubricated technique. But exercise extra caution with angles; drilling vertically intensifies risks of edge chipping and drill skating.

Stay Safe and Code-Compliant

Adhering to safety guidelines protects both the installer and the surroundings when undertaking any drilling project:

  • Wear protective goggles to shield eyes from debris
  • Secure hair and loose clothing
  • Ensure adequate workspace lighting
  • Follow local building codes for hole size limitations

Frequently Asked Questions

1. What issues can occur from using the wrong drill bit on glass tiles?

Trying to drill into glass tile with a regular metal drill bit usually does not work well and can be risky. These bits are not hard or durable enough to get through tough glass. They are very likely to break. Using the wrong drill bit can result in cracking or shattering whole tiles or tile surfaces.

2. How can I keep the drill bit from slipping around on the glass tiles?

Putting painter’s tape on the tile surface in an X shape under the point of drilling helps to hold the tile in place under the bit. The tape helps stop the bit from slipping. It also helps protect the glass and tile top edges from chipping too much when the bit goes all the way through. Making a small starting dent first likewise helps to keep the bit steady.

3. Do I need to use any liquid when I drill the glass tiles?

Yes, it is strongly recommended to apply a specialized lubricating liquid while drilling glass tile. The fluid helps control friction and prevent overheating where the diamond grit touches. Lubricating makes the drilling process much smoother with less resistance. This protects the tile and the drill bit.


Drilling nice clean holes through glass mosaic tiles brings unique challenges but gives nice-looking results. Be ready with diamond-tipped bits for glass, good preparation, controlled technique, and awareness of safety. Being patient and precise will help you make neat, consistent holes to transform any tiling project. Practice your new skills on leftover tile samples before drilling an installed backsplash or floor. With the right tools and approach, adding glass accent tiles is a very possible and eye-catching goal for ambitious home tilers.

Watch Craig’s video Tiling Tricks & Tools: Drilling Clean Holes in Glass