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Toughened Glass

What is thermally toughened glass?

• Standard: BS EN 12150 for thermally toughened soda lime silicate safety glass.
• Thermally toughened glass is producing by slowly heating, and then rapidly cooling, annealed glass.
• In North American terminology, thermally toughened glass is referred to as "tempered" glass.

Advantages of thermally toughened glass

• Thermally toughened glass is a Safety Glass as defined in BS 6206.
• Thermally toughened glass is considerably stronger than annealed glass of the same thickness.
• Thermally toughened glass is more resistant to thermal stress than annealed glass.

Disadvantages of thermally toughened glass

• Although stronger than annealed glass of the same thickness, thermally toughened glass is easily broken by impact from sharp objects.
• Although classified as a 'safety glass', broken panes of thermally toughened glass have no strength and will disintegrate easily. This must be taken into account if thermally toughened glass is used as a barrier.
• Thermally toughened glass cannot be worked after toughening.
• Thermally toughened glass may suffer from the problems associated with nickel sulfide inclusions. These may be reduced, but not entirely eliminated, by the process known as heat-soaking.
• Thermally toughened glass may suffer from roller wave distortion.

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