Spontaneous Glass Breakage


Spontaneous Glass Breakage

“This blog post discusses multiple reasons for glass breakage focusing on a rare occurrence known as ‘spontaneous glass breakage’ which can happen due to inclusions in a toughened glass panel- generally understood to be 1 in 10,000 pieces….”

Toughened glass is used for a huge range of applications including safety balustrades, canopies, walk-on floor glass, windows, tabletops and more. Toughened glass can however break, and can be broken fairly easily if you know how! Take for example a panel of 10mm toughened glass, which can be struck with a hammer in the centre and not break, but a small tap on the corner would shatter the panel into oblivion!

Glass is most vunerable on it’s edges and care should always be taken to protect glass edges when installed where possible, and particularly during installation as even lightly catching a piece of floor glass on its support framework can instantly be a very expensive mistake. Stresses on glass can also be a very common cause of breakage- ensure floor glass is installed perfectly flat and supported on its edges only (never in the middle) and when using toughened glass in a clamp system, for example in balustrades, ensure the glass clamps are all perfectly aligned to avoid any pressure points on the glazing. 

Glass can be broken either accidentally or intentionally for a large number of reasons- sometimes quite innocuously by stresses placed on the glass in installation, movement in timber or other materials that otherwise appears to happen ‘for no reason’.

There is also however a very rare, almost freak occurrence known as spontaneous glass breakage that can cause the toughened glass panel to break for no obvious reason and is due to a naturally occurring inclusion in the glass panel. Our suppliers suggest that such a breakage can occur in 1/10,000 panels.

There are a few types of inclusion both solid and gaseous that can cause a rare spontaneous breakage, the most likely of these being a nickel sulphide inclusion- these are a very rare but naturally occurring particle that is potentially present within all glass. An inclusion would be so small that its impossible to trace or see with the naked eye.

Nickel sulphide is a complex material that has two main states, one which is stable at high temperature and one which is stable at lower temperatures. The spontaneous breakage issue only affects toughened glass because it is created during the toughening process where the glass is heated to very high temperatures, transforming the inclusion into a high temperature stable form, the cooling process is then too quick for the inclusion to revert back to the lower temperature stable form. The reverse transformation occurs slowly over time, sometimes over years and is accompanied by an increase in volume which although very small is sometimes sufficient to cause glass breakage.

As a nickel sulphide inclusion (although extremely rare) is naturally occurring and potentially present in all glass, from a glass processing and supplier perspective and as confirmed by The Glass and Glazing Federation, such would be considered inherent and therefore not a ‘failure’ of the product itself.




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