THINGS YOU NEED TO KNOW ABOUT TOUGHENED GLASS

Toughened glass, or safety glass, or tempered glass is ordinary float glass that has been made force-resistant and hence, this type of glass is six times as hard to break as ordinary glass panes. Moreover, if the glass does indeed break, it will break into small, blunt, cube-shaped pieces due to stress patterns within the glass. In a nutshell, nobody gets hurt.

How is Toughened Glass Made?

There are mainly two ways in which glass can be toughened –

• Tempering Glass with Heat and Cold

Most toughened glass or safety glass is made by tempering, a process in which ordinary glass is heated up to a temperature of around 620°C for some time followed by abrupt cooling using jets of cold air. As a result of this process, the outside of the glass is forced into compression while the inside remains free to float for some time (creating tension on the inside). The higher the thermal expansion of the glass and the lower its thermal conductivity, the higher will be the level of residue stresses, and as a result of this, the stronger will be the resulting glass.

• Tempering Glass with Chemical Reactions

Normal float glass is submerged in a bath of potassium salt at 300°C. When the salt dissolves, it is indicative of its separating into ions. The potassium ions are now free to replace sodium ions in the surface of the glass. Potassium ions are 30% larger than sodium ions; the process brings the outer surface under compression while the inner surface remains the same. This creates a tension inside and now the force required to break the glass has to be much greater (more than the compressive forces). Hence, this method aims at strengthening the glass by chemical ion exchange.

Types of Toughened Glass

There are mainly five different types of toughened glass in existence. They are –

• Clear toughened glass

• Laminated toughened glass

• Reflective toughened glass

• Tinted toughened glass and

• Frosted toughened glass

Advantages of Toughened Glass

Tempering of glass has a lot of benefits –

• Toughened glass is about  to 6 times stronger than normal float glass. Moreover, the process of tempering does not affect any other property of the glass. Hence, with the same visible light transmission as normal float glass comes simply greater strength

• Toughened glass is able to withstand massive differences in temperature (of up to 250°C) whereas normal float glass can handle only up to 40°C

• Tempering of glass renders it difficult to break and even when it does due to whatsoever reasons, it will fall apart into very small, blunt, cube-like pieces that do not cause fatal injuries

• Toughened glass is highly resistant to electric and thermal shock

• Its high durability makes frequent replacement redundant. Hence, the glass can easily be used for a long, long time

Application/Uses of Toughened Glass

Toughened glass has a host of uses 

• Toughened glass is typically used in commercial applications where wind, snow and thermal impact make the use of normal glass futile. Moreover, they are also used in high-rise buildings due to their ability to handle heavy load easily

• They are generally used in the windshield of sports cars that operate on very high speeds

• When mixed with tinted glass, laminated glass, insulated glass, etc. toughened glass can be used in various components of a building such as escalator side panels, balustrades, handrails, skylight glazing, etc.

• Places of national and international importance use bulletproof glass for the safety of VIPs. Bulletproof glass is prepared by combining toughened glass with laminated glass.