Glass Cutting: Breaking the Glass

March 21st, 2021

After you make your cut, you need to break the glass apart. Start by gripping the glass so that your thumbs rest on either side of the score mark. Your two index fingers should securely grip the underside of the glass on either side as well.

While holding the piece firmly, rotate both hands out and away from each other in a quick, snapping motion with your wrists. If you scored the glass correctly, it should break cleanly along your line.

NEVER try to break the glass using an inward motion! This puts pressure on the strong, unscored underside of the glass first and could instantly shatter the glass in your hands!

Sometimes you’ll need to make a score that’ll be difficult to break with your hands. A great tool for breaking lines like these is a pare of running pliers. The tool gets its name from the way it causes the glass to crack or “run” cleanly along a score line. The bottom jaw of the pliers has a raised lip in the center that acts as a pressure point on the glass.

To use your running pliers, place them along the edge of the glass with the lip under the score line. Then simply squeeze the pliers together, forcing the glass to gently separate along the score.

When making stained glass artwork, it’s important not to let the little things frustrate you. There’ll always be those times when your glass doesn’t end up snapping the way you want it to. Heck, I’ve been working with stained glass for 5 years now and I don’t think there has ever been a project where the glass behaved exactly the way I wanted it to. You just have to learn from what went wrong and try again.