Tempered Glass – Important Things to Know

Tempered glass, also known as toughened glass, is stronger and safer than ordinary or annealed glass. It doesn’t break into large sharp shards that can lead to hazardous accidents, which is why it is widely used in automobiles, furniture, shower enclosures, windows and doors of commercial and residential buildings. To find out everything about this special glass type including its manufacturing process, advantages and disadvantages, keep reading this blog-post by a tempered glass manufacturer.

Manufacturing Process

Tempered glass is made from a float glass and can be toughened in two ways.

• Cold and Heat Process

Annealed glass or float glass is heated at around 620o Celsius in the furnace. The heated glass is then cooled rapidly by a blast of air within three to ten seconds. This makes the surface shrink leading to tensile stresses while the interior glass surfaces develop residual compressive stresses. These stresses improve the strength of the glass making it hardy than ordinary glass.


After the toughening process, the glass has greater resistance to thermal stresses and shock. In fact, it can also improve its flexural and tensile strength. However, the other characteristics such as colour, clarity, chemical composition, light transmission, hardness, expansion coefficient, thermal conductivity and solar transmittance of the glass remain unchanged.




• The thermal conductivity of the glass is lower when the coefficient of thermal expansion is higher.
• The glass becomes stronger with a higher level of residual stresses.
• Thermal toughening takes a relatively shorter duration of time and can be applied to many glass types.
• When the tempered glass breaks, it shatters into a large number of pieces due to the high amount of energy stored in residual stresses. But these broken pieces are less hazardous than sharp shards of ordinary glass.
Tempered glass cannot be cut after the toughening process. Manufacturers cut a float glass into the desired size prior to the procedure.

• Chemical Reactions

Another way to strengthen float glass is to use chemicals. The glass is submerged in a bath containing a potassium salt (which is usually potassium nitrate) at 300o Celsius. When the salt is dissolved, it separates into its constituent ions releasing the charged potassium ions which are replaced by the sodium ions on the glass surface. As sodium ions make way for the glass to enter the solution, they leave behind gaps which are filled with larger potassium ions which are thirty percent larger. The glass’s outer surface is forced under compression as the molecules expand. The interiors, on the other hand, remains the same as it is placed under tension. Hence, the chemically strengthened glass is made sturdier by ion exchange.


Tempered glass is preferred for several reasons and they are:


• Strong

strong glass


As it is already established that tempered glass is stronger than any ordinary glass as it can withstand strong impacts like strong winds, blows and other harsh weather conditions. This is the reason why it is used in automobiles and high-rise buildings.


• Safe

When this glass breaks due to pressure, small pieces are formed, unlike large shards that can be dangerous leading to cuts and severe injury. For this reason, shower doors and vehicle windows are made of this glass.

• Resists heat

resists heat


It is heat resistant and may not shatter due to extreme hot temperature. That’s why the automobile industry uses this glass extensively to ensure safety to the driver and co-passengers.

• Clear

This glass has a clear view which is why automobile windshields are made from it. This is important because the driver must get a clear view for uninterrupted driving.

• Available in a wide variety

Patterned, frosted, clear and engraved are some of its different types that are available in the market. The patterned types are usually used for shower enclosures while the clear ones are used for manufacturing windshields.


Though this glass is safer and stronger than ordinary glass, it has a few disadvantages and they are:


  1. Once it’s toughened, it cannot be cut further.
  2. Self-breakage is a common thing in this glass type.
  3. The outer surface of this glass can have irregularities like wind spots.
  4. The thickness of the glass is not the same after tempering.


That’s everything you need to know about tempered glass which is a float glass toughened to increase its strength. It can be used in homes, offices, and automobiles. If you require it, then get in touch with a tempered glass manufacturer and order it right away. You can also contact us for more details!

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