Learning how to cut mirror yourself has many benefits. You can create any design or shape you desire without settling for what’s available on the market. You can also save money on expensive mirror pieces since you can style them yourself. Cutting mirror is actually a misleading term, as you will not be cutting so much as performing what is called a controlled break. In this process, you will score, or scratch, the surface of the mirror where you want to cut it. This creates a weak point in the glass. Once you apply a little pressure along the line you cut, a break will occur. This is referred to as “running the score.” With a little practice, you can create beautifully cut mirrors.
Select and purchase an uncut mirror, and determine the pattern desired. It may be helpful to draw a diagram.
Clean and dry the glass thoroughly before beginning. This is a very important step, as even the slightest speck of dirt or dust can cause interruptions during the scoring process. This can cause the glass to chip or even break.
Place your wheel cutter vertically, or straight up and down, on the reflective side of the mirror. If you don't position the cutter straight, you can run the risk of an imperfect cut or break the mirror.
Apply a slight downward pressure to the cutter as you roll it along your pattern, and score the mirror as you go. With most mirrors, you should hear a screeching sound if you are doing it correctly. If you don't hear a sound, that means you aren't pressing hard enough. If you press too hard, you will notice tiny chips from the cut. These may get under your wheel and damage or dull your cutter.
Continue scoring the mirror until you have completed an outline of your pattern.
Place your running pliers so the bottom jaw touches the score on your mirror. The top jaw should touch the mirror about 1/2 inch (1.3 cm) on either side of the score line. Squeeze the pliers, which will cause them to separate, and thereby widen the score line. This widening will cause the score to crack along the rest of your line in a very controlled breaking pattern.
Seal the edges of the newly cut mirror with mirror edge sealant or other hermetic coating. You can find these materials at a hardware store. You can also opt for clear fingernail polish.