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Toughened Glass – Where and When It Should Be Used

Roughly four times as strong as regular glass, ‘toughened’ or ‘tempered’ glass is used in a wide variety of applications, both commercial and domestic.

This extra strength and resilience makes toughened glass ideal as ‘safety glass’, which is a variety of glass that (when broken) breaks into small pieces rather than large (and usually very sharp) fragments which pose a direct safety threat.

In domestic applications, such as shower screens and sliding doors in residential properties, toughened glass is the most suitable glass variety currently available. What’s more, it’s also used in a variety of other applications, such as automobile windows as well as a component in bulletproof glass, which is a testament to its superior strength.

How is Toughened Glass Made?

Toughened glass differs to regular glass, not only in its superior strength (both physically and thermally), but also in its production. While it starts as float glass, just like regular glass, it undergoes a strengthening process which makes it stronger and more resilient than other glass varieties. The toughening process is conducted before the glass has been given its final shape (for example, cut into a window pane), as any additional machining or working once the glass has been toughened would cause it to shatter.

This toughening process is called ‘tempering’ and involves heating the surfaces of the glass in a furnace to temperatures as high as 600°C. After the glass has been heated to the required temperature, it’s then cooled very quickly by blasting cool air over it for pre-determined periods (usually between three and ten seconds) of time. The tempering process takes just a few minutes and can be applied to most types of glass.

The result of the cool air meeting the hot glass causes the surfaces of the glass to shrink and tensile stresses to develop. The tensile stresses and the contracting of the glass result in what are known as ‘residual compressive surface stresses’ on the surface and ‘compensating tensile stresses’ in the interior. This creates a tension zone in the glass which takes up approximately 60% of its mass, resulting in superior thermal, physical and flexural strength to other glass varieties. However, the colour, clarity and chemical composition remain unchanged, as does its stiffness and transmittance.

Why Does It Crumble Rather Than Shatter?

Toughened or tempered glass is used as ‘safety glass’ because it shatters into a greater number of pieces (these pieces aren’t as sharp or as hazardous as glass shards) than regular glass when broken, but what makes it shatter this way?

It’s the compressive and residual stresses (these stresses contain higher amounts of energy) in toughened glass that cause it to crumble rather than shatter, as the more energy contained, the greater the number of stress points. The compressive stress in toughened glass must be at least 10,000 psi, and for it to be used as approved safety glass, the compressive stress of the surface must exceed 15,000 psi. If you want to observe the compressive stress of toughened or safety glass for yourself, you can use a pair of polarised sunglasses or a polarised light.

The Advantages and Disadvantages of Toughened Glass

For most domestic and commercial customers, the advantages of toughened glass outweigh the disadvantages. Nevertheless, it’s always good to be aware of both as this helps you to make informed decisions about the toughened glass products that you invest in at home or at work.



As mentioned above, in most cases the advantages of toughened glass outweigh the disadvantages.

Toughened Glass Applications

Toughened glass is used in a variety of domestic and commercial applications, most notably applications in which safety, strength and thermal resistance are deemed to be important. This has resulted in toughened glass being used in the following, among many other, applications:

If you’re replacing the windows, shower screens, glass splashbacks or sliding doors in your home, you’ll be using safety glass which meets the rigid Australian requirements for domestic applications.

Rockingham Glass are glass experts with over 35 years’ industry experience backing us up. Whenever you’re in need of glass replacements (we also offer a 24-hour emergency glass replacement service) or glass products, including a wide range of shower screens, don’t hesitate to give Rockingham Glass a call. We look forward to assisting you with your toughened and safety glass requirements.

“I have had rockingham glass out for a second time to replace some windows and yet again they have not disappointed, they are excellent. Great workmanship and excellent service. They are the only ones to use and I know as I have used the others in town. Rockingham glass came and quoted a few weeks ago and after having a different company replace some windows and completely stuffing it up I was hopefully of a better outcome and they did not disappoint, wow what a difference really professionals make. they installed a new sliding door and doggy door as well as a new window. They have done an amazing job, very clean and tidy and looks so good. I cannot wait to get others done. Thank you so much Rockingham glass I can not recommend you enough.”

Lee M

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