A guide to the
4 main glass types
Flat glass is produced using the Float Process after which it undergoes various processes to suit different applications.
There is an extensive range of technologies in the glass industry which can often be confusing.
This guide will explore the main 4 glass types predominantly used in the glazing industry today.
With this information you can be condifent that you understand glass types and their intended use.
Float Glass Process,
A brief history
The Float Process allows Larger and more consistant panes of glass to be manufactured than ever before
- Invented by Sir Alastair Pilkington in 1952
- Worldwide there are now more than 260 Float Glass Plants
- Glass panels up to 3 metres wide and between 0.4mm and 25mm thick can now be manufactured
- Float Glass Plants today produce a combined output of around 800,000 tonnes of glass per week
- The Float Glass process is today considered the world standard for high quality glass manufacture
The 4 main Glass Types
Used across the glazing industry today
Annealed
Basic product formed from the annealing stage of the Float Process.
The molten glass is cooled slowly to room temperature, relieving internal stresses.
Annealed glass is used as a base product to form more advanced glass types.
If broken there will be large sharp shards.
Heat Strenghtened
A semi toughened glass.
Annealed glass is heated back up to 650 degrees then cooled quickly. This increases the integral strength, making it twice as tough as annealed.
It is used when there is a concern tempered glass might break into thousands of small pieces.
Toughened
The most common glass used for structural applications.
Annealed glass is heated to 700 degrees by conduction, convection and radiation and then cooled rapidly.
The cooling process is accelerated by blasts of air to both surfaces. the differing rates of cooling between the inside and the surface produces an impressively strong structure, 5 times stronger than annealed.
If broken under extreme pressure, breaks into small square fragments rather than long dangerous shards.
Laminated
All glass can be laminated, most commonly two sheets of glass are laminated together with a Polyiynil Butyral (PVB) interlayer.
Laminated glass is normally used for security, because if broken will not fall to pieces as it is held together by the interlayer of vinyl.
A veriety of other uses such as UV resistance and sound (DB) reduction can be achieved through the use of differing laminates
Laminated glass is not commonly as strong as Toughened.
