Frequently Asked Questions...
What is Float Glass ?
Float glass does not resist high stresses from the impact of an object. Its breakage pattern is uneven and when broken, it shatters into large uneven pieces with sharp / jagged edges. This is not desirable as the risk of injury to human beings is greatly increased.
What is Strengthened Glass ?
Heat strengthened glass is about twice as strong as annealed float glass and is used generally as a protection against thermal breakage. However its strength is lesser than Tempered Glass and the breakage pattern is still uneven. This is not classified as safety glass.
What is Toughened Glass ?
Toughened glass is four times stronger than float glass and offers the highest resistance to impact. It is ideal for application in doors etc. If broken, the whole pane of glass shatters into small pieces of blunt granules that are relatively safe. Additionally, the shattered glass falls out quite easily. This is classified as safety glass.
What is Thermal Breakage ?
Glass which is not heat treated (heat-strengthened or toughened) can experience thermal breakage. In those applications where thermal stress may be a concern, the glass should be toughened. In non-heat-treated glass, the risk of thermal breakage is greatest when the central area of glass becomes hotter than the edge. This condition can occur when the centre of the glass is heated by the sun and the edges remain cool. Under these conditions, the centre of the glass expands but is restricted from natural expansion by the cool edges. This results in stress within the glass that could cause thermal breakage. The degree to which the central area of the glass becomes hot is largely dependent on the solar absorptance of the glass, which varies between different types of glass as shown in the following table.
