• Ella Townsend


Updated: Mar 28

Flat glass is what is used in the balustrade industry to suit a host of various applications and requirements. With a vast array of technologies in the glass industry, our guide is on hand to help you get to grips with the four main glass types used in today’s industries.

Essentially, the definitive strength of glass is associated with the rate at which it’s cooled. As we touched on, there are four main types, each varying in strength. They are as follows:

Annealed Glass

Annealed glass is a basic product fashioned from the annealing stage of the float process. It’s formed when the molten glass is left to cool slowly in a controlled method until it reaches room temperature. By doing this, it relieves any internal stresses that may be found in the glass. If this slow, controlled cooling approach was not adopted, the glass would crack following a comparatively little change in temperature or minor shock. Due to annealed glass being the basic option, it is used as a base product in order to create more advanced glass types.

Heat Strengthened Glass

This type of glass is semi-toughened. The heat strengthening process requires the heating of the previously mentioned annealed glass to reach around 650 to 700 degrees Celsius before being cooled quickly, although not as quickly as toughened glass, but we’ll get on to that next.

The heat strengthening process is effective in increasing the thermal strength of annealed glass, doubling its toughness in comparison to annealed glass’ normal state.

If it breaks, the fragments are similar in size to annealed glass, but with a higher probability of staying together.

This glass isn’t often used for the creation of balustrades or similar structural applications due to its limited strength when compared with tempered or toughened glass. However, it can sometimes be specified if the concern about tempered glass fracturing into thousands of small pieces is present.

Tempered or Toughened Glass

Tempered or toughened glass is used as the most common form of glass in balustrades or similar structural applications. It’s created using annealed glass once again but is heated to around 700 degrees Celsius by conduction, convection and radiation. The cooling process is accelerated by a constant and simultaneous blast of air on both surfaces. Thanks to the surface and the inside of the glass cooling at alternative rates, different physical properties are produced. This means that the glass then offers compressive stresses in the surface, balanced by tensile stresses in the body of the glass.

The toughening process provides the glass with a strength four to five times stronger and safer than regular annealed or untreated glass.

The counteracting stresses or surface compression gives toughened glass its heightened resistance to breakage, and if it does break, it produces small, consistent, normally square fragments, instead of long, dangerous shards that are much more liable to cause an injury.

Laminated Glass

Any of the three types of glass we have mentioned can be laminated. The example you are likely to see most of will be two sheets of toughened glass that are laminated together with a Polyiynil Butyral (PVB) interlayer that is 1.52mm thick.

Laminated glass gives users many benefits. First off, you get assurances as far as safety and security are concerned. Rather than shattering on impact, laminated glass is held together by the interlayer we mentioned. This decreases the safety hazard associated with shattered glass fragments, while also, to some extent, the security risks related to easy penetration.

If a glass panel shatters or breaks, it’s extremely unlikely that both of the laminated panels will break at the same time. This means that the non-damaged panel and interlayer provide support for the broken glass and keep it in place as edge protection until it is replaced or appropriately secured.

What’s more, another increasingly common interlayer is the SGP Interlayer. The product gives a significant five times the tear strength and a huge 100 times the rigidity of standard PVB! In the unlikely occurrence of both panes of toughened glass breaking, the SGP is there, in most applications, to hold the glass in place. SGP offers boosted impact performance levels and far superior protection against adverse weather conditions.

An array of other interlayers are available that utilise various other technologies to the application. Structural interlayers can be introduced to advance the strength of the glass where high loadings are essential. Another example is adding coloured interlayers that can be used to provide extra privacy or added aesthetics. Other properties such as sound dampening and fire resistance can also be incorporated into the interlayer.

For more information on the specifications you would like for your custom-made balustrades, get in contact with us here at ANY Weld, today!

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