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.
“They are, as it were, train-bearers in the pageant of life, and hold a glass up to humanity, frailer than itself. We see ourselves at second-hand in them: they show us all that we are, all that we wish to be, and all that we dread to be.... What brings the resemblance nearer is, that, as they imitate us, we, in our turn, imitate them.... There is no class of society whom so many persons regard with affection as actors.”
—William Hazlitt (1778–1830)