You might not have realised it but toughened glass can be found all around us, although you may also hear it referred to as safety or tempered glass as well. It’s used in everything from windows and public buildings to bathroom fixtures and fittings, cars, furniture… it’s everywhere!

It’s regularly chosen by businesses and homeowners alike because of the heightened security it lends to a property. It’s as clear and as see-through as any other kind of glass you can find but it’s up to six times harder to break - so absolutely perfect for shop fronts where you want to maximise visibility for passing customers but without compromising on safety and security.

But perhaps the cleverest feature of safety glass is that if it does break for whatever reason, it breaks into small cubed or rounded shapes so it doesn’t leave big shards of jagged glass everywhere, posing another risk. It achieves this because stress patterns have been positioned throughout the pane of glass, meaning it shatters in a certain way.


What can toughened glass be used for?

Because of its specialist properties, toughened glass has a wide range of applications across a vast array of different industries. You’re sure to find it in the windows of big apartment blocks and next time you walk past a bus shelter, take a look at the window… it will likely be safety glass.

Smaller applications include smartphone screens, drinking glasses and shower screens… so it really can do it all!


How is toughened glass made?

Toughened glass will start its life off as float glass, the kind that shatters into dangerous piece when broken. Before the glass itself can be toughened, it has to be cut to size since you can’t cut it once the process has been completed - the glass would simply shatter into little pieces, as explained above.

The process involves heating the surfaces of the glass in a furnace, with temperatures reaching above 600 degrees C. It’s then cooled down very quickly by blasting air over it in order to shrink the surface of the glass, which will create tensile stresses.

Once the process has been completed, the resulting glass has greater resistance to both thermal shock and stresses, as well as more effective tensile and flexural strength. But you’ll still have desirable features of glass such as colour and clarity, as well.

Find out more about tempered glass on the Scientific American website.