What Is Tempered Glass and What Is It Used For?

By August 15, 2022 February 17th, 2023 Blog

security glass

When you’re researching different types of safety and security glass, tempered glass is a term that you’re likely to come across over and over again. But what exactly is tempered glass and what are its applications?

There are many misconceptions floating around about tempered glass and whether or not you can use it for improving commercial security, so we wrote this guide to clear a few things up for you.

What Is Tempered Glass?

Tempered glass, also known as tempered safety glass, is a type of strengthened glass that is approximately four times stronger than standard annealed glass.

This type of safety glass achieves its strength by undergoing a special heat treatment, known as tempering. Essentially, the glass is heated up to extreme temperatures of 1,000+ degrees Fahrenheit, then cooled very rapidly using high-pressured blasts of cool air.

This thermal tempering process changes the properties of the glass, making it stronger and changing the way it breaks.

Whereas traditional annealed glass shatters into sharp, jagged shards that can fly dangerously inwards, tempered safety glass breaks apart into thousands of tiny, relatively harmless chunks.

This is why tempered glass is known as safety glass. The way it breaks apart greatly reduces the risk of injury associated with broken glass.

Whether a window is broken by inclement weather, an earthquake, a blast, an intentional impact, or an accident, tempered safety glass helps keep building occupants safe.

tempered glass security glass

Is tempered glass a type of security glass?

Although tempered glass is much stronger than standard window glass, it’s important to note that it is not intended for use as security glass. In other words, it is not designed to withstand forced entry, storm debris impacts, or ballistic impacts.

We’ll go over some ways you can reinforce tempered glass against such impacts a little further below.

What Is Tempered Glass Used For?

Tempered glass in vehicles

The most common place you’ve probably seen tempered glass, maybe without even knowing it, is in cars and other vehicles.

Because it’s so much stronger and safer than annealed glass, tempered glass has been used to reduce the chances of injuries caused by broken glass in vehicular accidents since around the 1930s.

If vehicles used regular annealed glass, even a minor accident could cause the windows to break and send a sharp shard of glass flying towards passengers’ faces, potentially resulting in very serious injuries or even death.

But, when tempered glass breaks in a car, it basically just crumbles apart, and the pieces are not as sharp or harmful to people.

tempered glass in a car

Tempered glass in commercial buildings

The other main application of tempered glass is in all types of commercial buildings. It is used for glass doors, windows, and storefronts for added strength and to increase the safety of occupants on the inside.

Tempered glass is also used for other architectural glass, such as glass stairwells, railings, floors, and walls. Wherever there is the chance of an accidental impact or where people are in close contact with glass surfaces in commercial buildings, tempered glass is generally required.

tempered glass for commercial buildings

Other applications for tempered glass

Besides being widely used in vehicles and commercial architecture, tempered safety glass is used for many other day-to-day applications, including:

  • Phone screen/other screen protectors
  • Glass furniture
  • Microwave and convection oven doors
  • Other appliances
  • Residential skylights
  • Shower and tub enclosures

Can I Reinforce Tempered Safety Glass Against Security Threats?

We mentioned earlier that tempered glass is built for safety, not security, so it is important to note that tempered glass, while great for safety, is not good for security. Because entrances to buildings are generally going to have tempered glass by code for safety, that makes these entrances particularly vulnerable to forced entry.

A common misnomer is that security window film can be used to secure tempered glass. In reality, however, if a security window film is applied, tempered glass will never be as strong when broken as annealed glass. Tempered glass becomes extremely unstable because it virtually explodes as the surface tension is released upon breaking. For this reason, tempered glass is less stable when broken than annealed or heat-strengthened glass which breaks into larger shards and remains whole in large sections, making it more stable with window film when broken, especially if it has been attached at the edges with a structural adhesive.

When it comes to commercial building security, there are only two main upgrades you can make to tempered glass doors and windows. These are:

  1. Replace with laminated security glass
  2. Retrofit with polycarbonate security glazing

Laminated security glass

Since tempered glass cannot effectively be secured, laminated security glass, such as Riot Glass® is often used as a replacement. The tempered glass is removed, and laminated glass is added in its place. Laminated glass can still comply with safety code because the interlayers used to laminate glass hold it together when broken.

Laminated security glass consists of two or more layers of strengthened glass with one or more thermoplastic interlayers, which makes it much harder to breach than any type of safety glass you can find.

Depending on the number of layers and thickness, laminated security glass can significantly delay or even completely deny forced entry attempts.

Polycarbonate security glazing

For the highest level of protection for your tempered glass, we recommend polycarbonate glazing shields, such as ArmorPlast®.

Polycarbonate security glazing can be retrofitted on top of your existing tempered glass. The key difference is that polycarbonate is much lighter and virtually unbreakable, even at thicknesses of just 1/4”.

For most commercial applications, we recommend ArmorPlast® AP25, a containment-grade (non-ballistic) polycarbonate glazing shield. AP25 keeps bad guys out and acts as a permanent alternative to boarding up your windows — protecting your business against rioting and looting or hurricanes and wind storms 24/7.

Campbell Can Help With All Your Glass Security Needs

Campbell Window Film, LLC is an authorized dealer and installer of Riot Glass® laminated security glass and ArmorPlast® polycarbonate security glazing.

Contact us today for a free consultation and learn how we can improve your building’s security by reinforcing tempered glass using one of these products.