Tempering in Glass
Tempering, or toughening, of glass is a process in which glass is first heated above its annealing temperature (about 720°C), and then rapidly cooled by jets of cool air, thus hardening the surface of the glass and leaving the center soft for a period of time. This creates internal stresses in the glass. If the glass is broken, it will break into many small pieces instead of simply cracking, making it far safer. Another advantage is that tempered glass can be up to four times stronger than regular glass. However, tempered glass cannot be cut to shape or drilled once it has been toughened.
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Famous quotes containing the words tempering and/or glass:
“Only after much tempering is steel produced.”
—Chinese proverb.
“I must sojourn once to the ballot-box before I die. I hear the ballot-box is a beautiful glass globe, so you can see all the votes as they go in. Now, the first time I vote I’ll see if the woman’s vote looks any different from the rest—if it makes any stir or commotion. If it don’t inside, it need not outside.”
—Sojourner Truth (c. 1797–1883)