Cutting Glass

To make stained glass windows and panels you need to practice cutting straight lines and curves from glass to acquire the knack and the confidence that make it look so easy.

Cutting glass is an easier process than you may think, requiring only a few tools. It has very little to do with strength and is mostly a matter of technique. Always observe safety precautions when cutting glass (see safety frame!) and keep children away while doing it.

The most essential tool is a glass cutter. Avoid cutters with more than one blade as they can be awkward to handle. Buy the best quality you can afford if you intend doing a lot of glass cutting. The cutter has a hard steel wheel which scores the surface of the glass and when pressure is applied to the reverse side of the glass, a fracture or run will allow the glass to be broken off in the desired shape. Practice first on 3mm / ⅛in clear glass, available from any commercial glass shop.



  • Don’t work directly on a kitchen table or work surface. Lay down some newspaper, brown paper or a piece of hard board.
  • Keep your work area clear of tiny fragments of glass – don’t be tempted to sweep them away with the side of your hand. Keep a brush and dustpan handy.
  • Store glass safely. Large pieces are best stored upright. Avoid storing too many offcuts together.
  • Wear goggles or safety glasses when cutting glass.


There are two different types of glass.

Machine-made glass, known as rolled glass, comes in a wide variety of shades and textures, and can be divided into two groups.

The first is opal glass, which isn’t transparent and is usually used for lighting as in Tiffany lamps. The other is cathedral glass, which is transparent and available in a variety of colors. The one side is shinier than the other due to the manufacturing process.

The second type of glass is antique glass, which is mouth-blown. This process produces irregular glass with some attractive color variations. If you look through it, you’ll notice little air bubbles trapped in it. It is much more expensive than rolled glass as it is hand-made. New antique glass is machine-made glass that imitates antique glass.

The basic techniques needed to create stained glass are the ability to cut glass and to snap it with confidence. Don’t be afraid of cutting yourself – the more confident you are handling the glass, the more successful you cutting and snapping will be. Practice straight cuts first.



Make lots of practice cuts first on some cheap offcuts of glass and don’t forget to oil the cutting wheel occasionally.




Practice holding the glass cutter until you feel comfortable with it. Hold it upright and apply firm, steady pressure down on to the glass surface, so that the base of the cutter is parallel to the glass.

Use a straight edge to guide the cutter. Holding the cutter firmly, pull it towards you to score the glass, easing off the pressure as you reach the end of the line being cut.

Take hold of one end of the glass, placing your thumbs on either side of the score line, and apply pressure upwards with your fingers on either side of the score line beneath the glass

The glass will break along the line with a sharp snap. Make sure you are holding it away from the work surface as it does this. Any rough edges can be smoothed later.

To cut a narrow strip of glass, score the line as before. Hold the main piece of glass in one hand and apply pressure with the pliers centrally on the other side of the scored line.

Apply a downward pressure on the grozing pliers, pulling slightly outwards from the glass, The glass should produce a clean break, as before, along the line scored previously.




Place the glass in position on the pattern. Use the cutting wheel as before to score the curve and work away from you, so your hand does not obscure the drawn line of the pattern.

Grasp the glass firmly with one hand and tap along the underside of the scored line using the ball end of the cutting tool. Start at one end and work along increasing the pressure

You will see fracture develop as you work along the scored line. The two pieces will separate and one will fall away to the work surface, leaving a smooth curve.

Where a sharp corner of the glass needs to be slightly rounded, carefully nibble away at the corner using the grozing pliers until you have achieved the required shape.


Smooth the edges with a glass file or carborundum stone. Work away from you so that the glass chips don’t fly upwards towards your face. Carefully sweep up these tiny chips from the work surface with a soft cloth and dispose of the cloth.



Glass cutter
glass cutter

Get used to holding the cutter – experiment until you find the grip that is comfortable for you. Then you need to get used to applying firm, steady pressure to the cutter as you move it across the glass, keeping the base of the cutter parallel to the glass. Use a lightweight oil to keep the wheel lubricated. Cut straight lines using a straight edge as a guide and simply snap the scored glass. Curved lines are scored following the lines of a drawn-out design. The ball end of the glass cutter is then used to tap the underside of the score, causing it to fracture along the line.

Click here to get the Glass Cutter used in this activity

Grozing pliersgrozing pliers

If you are cutting a lot of glass, or need narrow strips, it’s worth getting the grozing pliers. These are spring operated and help to grip the glass. They can also be used to ‘clip’ away any jagged pieces of glass.

Click here to get the grozing pliers used in this activity.