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What Is Tempered Glass? Uses, Benefits, and Limitations

| January 18, 2025

Tempered glass is often the go-to choice for homeowners looking to replace their windows and glass doors, and for good reason – it boasts exceptional strength and breaks into tiny, blunt fragments.

Picture yourself in your living room, enjoying the afternoon coffee, when suddenly, the ball your child is playing with hits the window. If that window is made of tempered glass, it will likely withstand the impact without breaking – after all, tempered glass is renowned for its ability to resist the most severe conditions, including hurricanes!

However, tempered glass isn’t used only in the window industry – it has a wide range of applications! In fact, many things surrounding us every day are actually made of tempered glass. Plus, beyond its remarkable strength, tempered glass offers other benefits that make it an attractive option. Curious to learn more? What is tempered glass exactly, how is it manufactured, and does it have any disadvantages? This article will answer all your questions!

Key Takeaways

  • Tempered glass is a type of safety glass that undergoes a heat-treatment process, which makes it approximately four times stronger than standard glass. Tempered glass shatters into small, blunt pieces, which reduces injury risk.
  • Tempered glass is widely used for windows, glass doors, shower doors, and other products like glass table tops or fridge shelves. It is a staple in many industries due to its unmatched durability, strength, and compliance with safety codes.
  • Despite its benefits, tempered glass has limitations, including higher costs and the lack of possibility to be repaired once damaged, potentially necessitating full replacement. It also does not offer UV protection.

What Is Tempered Glass?

Tempered glass is a type of safety glass. It undergoes a special heat-treatment process that aims at enhancing its strength and safety properties.

Besides improving its strength and durability, the compressive stresses on the tempered glass surface prevent the glass from breaking into large shards like annealed glass. Instead, tempered glass breaks into small chunks. This significantly minimizes the risk of injuries because these small glass fragments are less likely to penetrate deep into the skin.

Given the above, tempered glass is considered four times stronger than standard annealed glass.

How Is Tempered Glass Produced?

Tempered glass is usually made from annealed glass, which goes onto a roller table and transported into a furnace. There, the glass is heated to approximately 1,148°F (620°C), which is above its transition temperature. Immediately after, the glass is rapidly cooled. This cooling process is called “quenching,” and it lasts only a few seconds. During this glass tempering process, high-pressure air cools the glass surface rapidly, while the center cools more slowly. Because of this, the center remains in tension, and the surface goes into compression. This is what makes tempered glass so strong.

However, there’s another way to manufacture tempered glass, and that is through chemical tempering. During chemical tempering, several chemicals exchange ions on the glass surface. This results in compression. Nonetheless, this method is rarely used in the window industry (or other industries, for that matter) because it is too expensive.

It is worth noting that tempered glass is cut before this entire process. Once it undergoes the heating and cooling processes, its size and shape cannot be changed anymore.

Key Benefits of Tempered Glass

Here are the key benefits of tempered glass:

  • It is incredibly strong – stronger even than laminated glass, not to mention standard annealed glass. This means that tempered windows will last longer than windows with annealed glass. This also means that tempered glass is perfect for homes in regions with hurricane risks, as it won’t break that easily in case of impact or strong winds.
  • In the event of breakage, tempered glass shatters into small, blunt pieces rather than sharp, dangerous shards. This significantly minimizes the risk of injury, making it a preferred choice for shower doors, glass doors, and large windows.
  • Tempered glass is heat-resistant, so it’s perfect for kitchen appliances or shower doors.
  • The manufacturing process of tempered glass does not affect its clarity, making it perfect for windows, doors, and window walls.
  • Tempered glass is also less susceptible to scratches compared to regular glass.

Where Is Tempered Glass Used?

Tempered safety glass is a versatile material used in a wide range of applications due to its strength and safety features. Common tempered glass applications include:

  • Windows
  • Doors
  • Skyscrapers and commercial buildings
  • Frameless glass doors
  • Glass installed near stairways
  • Elevators
  • Swimming pool enclosures
  • Mobile phone screen protectors
  • High-risk zones like wet areas (e.g. frameless shower doors)
  • Glass table tops
  • Glass shelves
  • Cooking and baking appliances
  • Oven doors
  • Touchscreen phones
  • Fridge shelves
  • Passenger’s window in automobiles

Building codes often specify that windows, doors, and other glass structures in certain locations need to have a type of safety glass – be it tempered or laminated. As such, before installing anything made of glass, make sure to check local building code requirements.

Limitations of Tempered Glass

While tempered glass offers numerous benefits, it does have some limitations. Here are some of the most important disadvantages of tempered glass:

  1. While stronger than laminated glass, for example, it does not resist break-ins too well. Why so? Because with enough force, a burglar can break a tempered glass window because even a tiny crack is enough for the entire window to shatter. A laminated window, on the other hand, keeps the glass fragments together when it breaks. Therefore, the intruder would have to strike the glass repeatedly to make a tiny opening.
  2. Tempered glass costs more than annealed glass (but is less expensive than laminated glass).
  3. Once tempered glass is damaged, it cannot be repaired and typically requires a full replacement, which can be quite expensive.
  4. Tempered glass does not provide UV protection.
  5. Tempered glass is less effective at sound insulation than laminated glass.
  6. Tempered glass may break out of a sudden because of impurities within it.

Alternatives to Tempered Glass

While tempered glass offers numerous benefits, you can also consider some alternatives, which may even be a better fit. Let’s find out more about them!

Tempered Glass vs Laminated Glass

Both laminated and tempered glass types are safety glass but their structure and manufacturing processes differ. While tempered glass has one glass layer, laminated glass consists of one or more glass layers separated by a polymer interlayer. This interlayer strengthens the glass and keeps glass fragments together in case of breakage.

Although laminated glass is not as strong as tempered glass, it is better for high-risk areas and windows prone to break-ins (e.g. basement windows) because the glass doesn’t really break. One would need to strike it repeatedly to make just a tiny crack. Plus, laminated glass can be made of tempered glass – in this case, it is twice as strong as standard tempered glass. Additionally, laminated windows block up to 99% of harmful UV rays, which are absorbed by the layer between the glass sheets.

However, laminated glass is generally more expensive than tempered glass due to its complex manufacturing process. It is also less heat-resistant than tempered glass.

Security Window Films

Security window films are another alternative to tempered glass, being an excellent method to improve the security and safety of existing windows or doors. These window films are made of polyester and are applied directly to the glass. If the window breaks, this layer will hold the glass fragments together, as if the glass is laminated.

Safety and security films can be applied on toughened glass, laminated, or annealed glass. They are also available in various thicknesses, and their effectiveness depends on material quality, window structure, and quality of application. Another advantage of security films is that they provide UV protection. Last but not least, they’re the most budget-friendly option we’ve mentioned so far.

Naturally, a security film does not make a window as strong as a laminated or a tempered window, and it doesn’t have the same lifespan. But it can definitely prevent injuries and slow down an intruder who wants to break into your house.

Get Magic Windows and Doors – With Laminated or Tempered Glass!

If you’re planning to replace your windows, you should definitely give Magic a call! Since we’ve brought glass production in-house, our company takes the lead in the industry – after all, we manufacture our windows from A to Z! This means we can advise you on everything glass-related and fully personalize your windows and doors. Whether you want tempered or laminated windows – or maybe laminated windows made of tempered glass – we’re here to manufacture the windows of your dreams!

But this isn’t the only aspect that makes us stand out in the industry! Our windows, doors, and window walls feature revolutionary technologies that boost their durability, strength, functionality, and energy efficiency. Two of our most praised technologies are the Hybrid Fusion Frame, which lasts 40 years even in the most extreme temperatures, and the Parallex Hardware, which makes our products crankless and hingeless!

Curious to learn more? Book your free consultation today and get the best windowy piece of advice in the GTA!

Final Thoughts

All things considered, tempered glass is a remarkable material that offers enhanced strength, safety, and durability. Its unique properties make it indispensable in various applications, from architectural glass and shower doors to consumer products like mobile phones and kitchen appliances. It goes without saying that the benefits of using tempered glass, such as its shatter-resistant nature and scratch resistance, far outweigh its limitations, making it a preferred choice for many.

Needless to say, the importance of tempered glass in modern life cannot be overstated. However, if you plan to replace your window or door units and are considering using tempered glass, make sure to compare it thoroughly to laminated glass. This will help you understand which safety glass is better for your house.

Frequently Asked Questions

Is tempered glass unbreakable?

Tempered glass is not unbreakable, but it is four times stronger than standard annealed glass, and if it does break, it shatters into tiny fragments, thus significantly reducing injury risk.

What is the difference between tempered glass and regular glass?

Tempered glass differs from regular glass by being approximately four times stronger than regular glass due to a heat-treatment process that involves heating and rapid cooling. Plus, tempered glass breaks into tiny fragments, while annealed glass (regular glass) breaks into sharp, dangerous shards. This makes tempered glass a preferred choice for applications requiring durability and impact resistance.

How to tell if the glass is tempered?

You can tell if the glass is tempered by checking one of its corners – most manufacturers mark that the glass is tempered. Additionally, you can test the glass with polarised lenses – if the glass is tempered, it will have a distinctive pattern, and you’ll see spots that darken.

How many years does tempered glass last?

Tempered glass may last more than 30 years if maintained correctly.

Is double-pane glass tempered?

Double-pane windows can feature tempered glass. However, double-pane windows can also incorporate laminated glass or annealed glass, depending on the preferences of the buyer.

What are some alternatives to tempered glass?

Laminated glass and security window films serve as effective alternatives to tempered glass. These options provide enhanced safety and protection, making them suitable for various applications.

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