You need to cut glass for various home improvement projects, such as replacing window panes and creating custom mirrors. While it may seem intimidating, with the right tools and techniques, you can manage to cut glass like a pro. Our guide will walk you through what to know about cutting glass, including understanding the basics, taking safety precautions, and troubleshooting common issues. For cutting a hole through glass, read our guide for drilling through glass.
Types of Glass Suitable for Cutting
Not all types of glass are suitable for cutting at home. These are the most common types that can be cut:
- Sheet glass
- Plate glass
- Float glass
- Antique or salvaged glass
Tempered glass, safety glass, and some types of laminated glass can’t be cut using standard methods and require specialized tools and techniques.
Tools for Glass Cutting
To cut glass effectively, you’ll need the following tools:
- Glass cutter
- Cutting oil or lubricant
- Framing square or straight-edge
- Measuring tape
- Safety gloves
- Safety glasses
- Breaking pliers (optional)
- Grinding stone (optional)
Preparing Your Workspace and Materials To Cut Glass
Take time to set up a safe workspace and get your materials before starting the cutting process.
Safety Precautions
Safety should be your top priority when working with glass. Always wear safety glasses to protect your eyes from glass shards and dust, use thick gloves to prevent cuts, and work in a well-ventilated area to avoid inhaling glass dust. You may also want to wear a face mask or ventilator if you’ll be cutting a lot of glass.
Setting Up Your Cutting Surface
Choose a flat, stable surface for cutting glass. Cover the surface with a soft material such as felt or newspaper to prevent scratching the glass, and make sure you have plenty of good lighting so you can see your lines clearly.
Measuring and Marking the Glass
Double-check all measurements before cutting. You can use a permanent marker or grease pencil to mark cutting lines. Allow for a slight overhang when cutting glass for window panes.
A framing square is an invaluable tool for ensuring straight cuts. This Old House’s Tom Silva recommends this method: “Lay the glass on the sash and line up one corner of the glass with a corner of a clean, putty-free opening. Leave the edge of the glass about one-sixteenth an inch from the inside edges of the rabbets.”
How To Cut Glass
Now that you’ve prepared your workspace and marked your glass, you can start cutting. Follow these steps for a clean, precise cut.
1. Lubricate the Glass Cutter
Before scoring the glass, lubricate the cutter’s wheel with a drop of oil. This reduces friction and helps create a smoother scoreline.
2. Score the Glass
Scoring is the most critical step in glass cutting. Position your framing square along the cutting line. Hold the glass cutter vertically against the square. Apply firm, even pressure as you draw the cutter along the glass in one smooth motion. Listen for a continuous scratchy sound, indicating a good score.
If you don’t hear this sound, you may need to try again with slightly more pressure or replace your glass cutter.
3. Break the Glass Along the Score Line
After scoring, it’s time to break the glass. Position the scored glass with the line at the edge of your work surface. Hold the glass firmly on the table with one hand. With your other hand, apply downward pressure to the overhanging piece. The glass should snap cleanly along the score line.
For larger pieces, you may need to use breaking pliers to initiate the break.
Techniques for Different Glass Shapes
While straight cuts are the most common, you may sometimes need to cut curves or circles. Follow our guide if you need to drill through glass.
Cutting Straight Lines
Straight cuts are the easiest to make and follow the basic process outlined above. Use a straight edge or framing square to guide your cutter for perfectly straight lines.
Cutting Curves and Circles
Cutting curves requires a different approach. First, create a template of your desired curve using cardboard or plastic. Then, trace the curve onto the glass. Score along the curve in small, connected straight lines. Use breaking pliers to carefully remove small sections along the curve. Smooth the edges with a grinding stone.
For circles, use a circle cutter attachment for your glass cutter or score a series of straight lines to create an octagon, then grind it into a circle.
Finishing and Smoothing the Cut Edges
After cutting, the glass edges may be sharp or uneven. Finishing these edges is important for safety and appearance.
Grinding Rough Edges
Use a grinding stone or electric grinder to smooth rough edges. Wet the edge of the glass to reduce dust. Gently run the grinder along the edge in a back-and-forth motion. Rinse the glass, and check your progress frequently.
Polishing for a Professional Finish
For a polished edge, use progressively finer grits of sandpaper, starting with 120-grit and working up to 400-grit. Finish with a polishing compound and felt wheel for a glossy edge.
Troubleshooting Common Glass Cutting Issues
Even experienced glass cutters encounter problems occasionally. Here are some common issues and how to address them.
Dealing With Incomplete Breaks
If the glass doesn’t break cleanly along the score line, try tapping gently along the underside of the score line with the ball end of the glass cutter. If that doesn’t work, re-score the line and try breaking again. As a last resort, use running pliers to gradually work the break along the score line.
Fixing Chipped Edges
Small chips can be smoothed out with a grinding stone. For larger chips, it’s often best to re-cut the glass if possible.
Cutting Thick or Tempered Glass
Cutting thick glass (over one-quarter an inch) or tempered glass requires specialized tools and techniques. For these types of glass, it’s often best to consult a professional glass cutter or use a glass shop’s services.
