Manufacturers use tempered safety glass for many residential and commercial applications. In short, heat-treating makes tempered glass about 4x stronger than regular, annealed glass.
By design, when broken, tempered glass disintegrates into small pieces and is much less likely to do harm.
When shattered, tempered glass windows can help protect a building’s occupants and equipment from the hazards of large shards of fragmented glass debris.
Below, we discuss what makes this glass different from standard glass and its key benefits and potential downfalls.
What is Tempered Glass?
Manufactured through the glass tempering process, a thermal tempering heat treatment, tempered glass is much harder than standard glass. Regular, annealed glass undergoes this process to relieve internal stress, making the rigid, brittle material tougher and more impact resistant while changing how it shatters.
Manufacturers heat the glass in a furnace to a temperature of over 1,000 degrees Fahrenheit before rapidly cooling it with high-pressure air blasts, a step known as quenching. This cools the outer layers of the glass much more quickly than the internal layers, so when the inside cools, it pulls away from the outer layers. As a result, the inside remains in a state of tension, while the outside goes into a state of compression, with the resulting glass reaching about 10,000 psi of compressive stress and becoming up to four times stronger than standard glass. These competing forces are what make tempered glass so much stronger than annealed glass.
Tempering creates this type of glass that shatters into small rounded fragments instead of sharp jagged fragments; however, due to the internal stresses, it will completely shatter upon damage to any part of it. Ordinary glass shatters into sharp fragments referred to as spall and causes injuries in cases of storms or explosions.
What is Tempered Safety Glass Used for?
People also know tempered glass as “safety glass” or toughened glass, and it is used in car windows, shower doors, glass tables, and other installations that require higher safety standards. It is also common in residential and commercial settings, including frameless shower doors and large windows, where safety is a priority. While the manufacturing process does make tempered glass more resistant to force, it is not shatterproof glass or unbreakable in any way. For this reason, you shouldn’t use it to prevent intruders, but it does withstand more force than regular glass.
Building codes often require tempered glass in high-traffic or hazardous locations, including skylights and areas near stairways, as well as in some elevators where safety glazing is required.
The tempering process also makes the glass more resistant to damage from higher temperatures. That’s why you may see tempered glass used in situations where high temperatures are likely to cause glass to break, like in fireplace doors, kitchen appliances, or glass table tops.
Disadvantages of Safety Glass
One of the main advantages of tempered glass—its ability to shatter into tiny pebbles, also creates a disadvantage. Because tempered glass shatters completely upon impact, it can create a potential security risk. Motivated intruders may find it easier to gain entry because a single force can cause the entire window to fall apart.
Additionally, manufacturers cannot resize, recut, or reshape tempered glass after tempering. Glass manufacturers must complete all cutting, sizing, shaping, and edge finishing before they temper the glass. Once the tempering process strengthens the glass, it becomes too fragile to cut or modify without shattering. Damage to any part of it will cause the entire sheet of glass to shatter due to the internal stresses created during manufacturing, making rework impossible. Precision and custom installations are key to using this type of glass.
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If these disadvantages sound like they may be a deal-breaker for you, know that there are other window treatments that provide a sound alternative to tempered glass.
Tempered Glass vs Film: The Glass Tempering Process
One of the main alternatives to tempered glass is window film. In the tempered glass window film debate, window film tends to win out for a number of reasons. These multi-layer films significantly improve glass windows and doors’ protective capabilities, making them harder to penetrate, whether by forced entry or flying debris.
They hold broken glass shards together without changing the appearance of the window, helping protect people during breakage while also slowing forced entry.
Safety & Security Window Films allow you to upgrade your glass to code for a fraction of the cost of a full glass replacement. Building codes may specify that glass near certain hazardous locations, such as wet surfaces, doors, floors, ramps, and stairs, meet certain safety glazing requirements.
3M Safety Window Filmscan help you quickly and easily meet safety glazing impact requirements for far less than the cost of replacement windows. Bars and pubs increasingly use tempered glass to reduce the risk of injuries caused by broken glass used as a weapon.
Window Film Depot is a certified installer of 3M Safety & Security Window Films. When you contact us, we’ll get a better understanding of your needs, schedule an onsite consultation, recommend the best products for you and discuss installation logistics.
There are many options to enhance window and door safety in both residential and commercial installations, so the decision comes down to what will best suit your needs. If you’re unsure, contact Window Film Depot and our representatives will do everything we can to guide you to the right product for you.
