The real question is, how to cut glass without it breaking!
Glass is such a brittle material that it can be tricky to cut without it shattering. This is not just wasteful but could be dangerous. So always take care when cutting glass by wearing protective gloves and eye protection.
There are many different ways to cut glass depending on the job and who is cutting it from glass manufacturers right down to hobbyists.
It is a good idea to practice on scrap glass to increase skills before starting a project on real glass.
Small scale glass cutting is commonly achieved via scoring and breaking.
Scoring is achieved via the use of a specialised glass cutter. This is normally an inexpensive tool depending on design.
Place the glass on a flat surface. For best results smear some oil on to the area to be cut. Specialised glass oil available from stained glass stockist can be used or just plain kerosene. This improves the quality of the score. Some glass cutters have oil built into the handle which automatically distributes it as it cuts. To learn how to cut glass in a straight line, use a steel rule. It is a good idea to place a template drawn on paper under the glass as a guide for more complicated shapes.
Once the glass has been scored, it can be snapped to make it break along the line. This can be achieved in various ways depending what is being cut.
Large sheets can be broken on a table. Place the score along the edge on the table then push the part to be cut down.
For smaller sheets, grip the glass firmly, one hand on either side of the score. Use a snap action on the wrists to break the glass.
If the part to be cut off is thin, use glass cutting pliers. Again, a table is a useful tool. Line the score with the edge of the table with the biggest side on the table. Hold this firmly in place with one hand. Position the pliers in the middle of the section to be cut and grip the glass gently in them. Push down with the pliers and the glass should break along the score.
For wavy lines, score out the pattern using a template. Gently tap along one side of the score to help to loosen it. You should then be able to snap the glass by gripping it firmly at each side of the score and rotating the wrists gently.
If the wavy line is tight, use the glass pliers to gradually chip away at the unwanted portion of the glass so you cut into the arc.
It is a good idea to learn how to cut glass on pieces of scrap glass before moving on to the project in hand.
A number of tools are available. More expensive and specialised tools can be used to score the glass such as the Cutters Mate. This produces a more accurate result and reviewers have said it reduces wastage.
Another tool is an electric saw - a band saw can be used and there are special glass attachment blades available. This is a more expensive tool so is not suitable for small volumes.
A specialised CNC machine is used to cut glass on an industrial scale. These machines have specialised tools and sometimes have water or lubricant built into them.
The machine relies on computer programming to cut the glass rather than the skills of an operator.
Glass is cut to standard sizes or to order when it is manufactured.