Glass built to last

Susan Sinden of ESG Group explains why glass advances make the material one of the most versatile for creating modern, attractive and secure environments

Toughened glass was an important development early in the 20th Century – because it shattered into small granular fragments rather than potentially dangerous large shards. However, in the last few decades, glass processors have far exceeded this with huge advances in laminated toughened glass, made by sandwiching sheets of toughened glass together with a PVB (polyvinyl butyrall) interlayer. If a sheet of toughened laminated glass becomes damaged, the interlayer holds nearly all the glass fragments in place, reducing the risk of falling glass fragments. This lamination process has opened up a whole range of possibilities for the use of glass, in partitions, balustrades and facades.

Toughened laminated glass now allows us to vary the degree of strength and provide additional properties, by using different thicknesses of glass and types of interlayer, according to the intended purpose of the glass panel. With toughened laminated glass having greater tolerance to stress, we can increase the size of each panel, so that lighter, taller and wider expanses of glass can be used to create the modern uninterrupted vistas which are a feature of so many iconic modern buildings.

By selecting different technical interlayers, we can also introduce a range of added benefits such as fire resistance, sound reduction, ballistic protection, and even opacity, to each glass panel.

Using a fire-resistant interlayer provides a fire-resistant safety glass that is certified to the Certifire E30 and E60 tests, which assess glass for 30 minutes and 60 minutes of fire resistance respectively, for panels used in timber and steel doors and screens. This helps to ensure greater visibility and safety – the fire door delaying the spread of smoke and flames, while the glazed door panel allows a fire fighter to make a critical check for occupants, or a vital assessment of a situation, before tackling a blaze.

We can also utilise interlayers to provide sound attenuation. This can be an invaluable benefit in offices and boardrooms, where openness and clear sight lines are valued by a client, but confidentiality for sensitive discussions is essential. In domestic settings this is also a huge benefit in urban locations where street noise can be a problem.

Another option that is growing in popularity in both commercial and domestic settings is LCD privacy glass. This is created using a specialised technical interlayer, through which a small electric current is run, allowing the user to choose between transparency and opacity at the push of a button. When the current is passed through the interlayer, light is allowed through and the glass is made optically clear. Once the current is switched off, the panel instantly becomes opaque. In open plan domestic settings this is proving very versatile for screening and zoning living areas such as the bedroom or bathroom, and also in place of curtains or blinds, giving a minimalist approach to alternating between privacy or enjoying the view.

This switchable glass can also be useful for security. If potential thieves cannot see their target, they are often deterred from making an attempt to steal it. This type of glass is therefore increasingly being used by high-end retail outlets from car showrooms to jewellers, and even in banks, to protect tellers from armed robbers.

A further type of interlayer can be used with thicker sheets of toughened glass to manufacture high security, ballistic, and even blast-proof glass, helping to design into the built environment a degree of deterrent against criminals and terrorists. The characteristics of toughened laminated glass are such that even when the panel is damaged and its clarity compromised by fractures, it will normally stay in place. The glass panel may be dented or pushed out of shape, but it takes a long time and a high level of tooling to make an actual breach in high security glass, especially that designed to withstand ballistics. Law enforcement support will usually arrive well before the perpetrator would manage to achieve a hole large enough to enter the premises.

Glass has been a highly desirable element in construction since Roman times, simply because it lets in natural light. Thanks to developments in toughened laminated glass processing, despite the passage of many centuries, modern processed glass can now do so much more, keeping it firmly at the forefront of building materials development.

Susan Sinden is commercial director at ESG Group