To cut glass, score it first, then break it along the scored line. Lubricate the cutting line with light oil, then firmly press the cutter against the glass surface, scribing a line to form a cut or score. This score weakens the glass, making the panel more susceptible to splitting along the scored line. Use the running pliers to extend the score line by careful application of pressure.
Various tools can be used for cutting glass, including a rotary-wheel glass cutter, tile saw, band saw, ring saw and water jet cutter. When using a rotary-wheel glass cutter, make a shallow score on one surface of a piece of glass that is to be split into pieces. The scoring creates a split in the glass surface, encouraging the glass to break along the score using considerably less force. Trying to split a panel of glass without first scoring it is rarely successful, because the glass typically proves itself too strong and resistant to breakage. However, it does bend slightly if force is evenly applied.
Focus on breaking glass far from the edge of the panel for a clean break. Apply upward pressure underneath the already-scored line while simultaneously pressing downward on the sides of the glass away from the scored line.