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Does Tempered Glass Break & Is Shattered Tempered Glass Safe?

Updated: 06/28/2024

Normal glass, or annealed, is simply heated and cooled during the manufacturing process. Tempered, or toughened, glass goes through an additional step where it’s reheated to a high temperature and then rapidly cooled with forced air. This process creates intense pressure on the outer surfaces of the glass, making them compress while the inner layer remains in tension. This leads to a stressed state throughout the glass that improves its strength. As a result, tempered glass is much harder to break.

However, sometimes it can shatter – but in a way that makes it a safer choice for applications where there’s a risk of impact or breakage. Apex Tempered Glass has created this helpful guide to help you understand tempered glass better.

Tempered Safety Glass Applications

Tempered glass panels are known for their safety and durability, and they’re used in many areas of our lives.

Here are some common applications:

  • Construction: Tempered glass is all around us in buildings, from shower enclosures to sliding doors and windows. Building codes often mandate its use for skylights, glass railings, and areas with a high impact risk.
  • Furniture and appliances: Tempered glass adds a touch of style and functionality to furniture like glass table tops, glass shelves, cabinets, and refrigerator trays. Its heat resistance makes it ideal for oven doors and appliance components.
  • Safety zones: While not shatterproof, tempered glass offers increased safety in commercial glass projects – for display cases and storefronts. In vehicles, tempered glass is used for side and rear windows due to its safety features.

Toughened Glass Shattering: What Causes Glass to Shatter?

How easy is it to shatter tempered glass? It doesn’t break easily, as it’s up to five times stronger than traditional glass. However, tempered glass breaks and it isn’t invincible. Here are some reasons why it could break.

1. Extreme Impact

Tempered safety glass can take a significant punch compared to annealed glass. It can nevertheless break given the force applied is too high and intentional such as a heavy-hitting object like a sledgehammer.

2. Edge Damage

Nicks, chips, or scratches, especially on the edges, can act like stress concentrators. Imagine a tiny crack as a weak spot in a dam wall. When pressure is applied, even normal pressure, the crack acts as a focal point for the stress, making it more likely to break there. Over time, these imperfections can weaken the glass and increase the risk of shattering from minor impacts or temperature changes.

3. Stress from Improper Installation

During installation, tempered glass needs some wiggle room. If the frame is installed too tightly, it can restrict the glass’s natural expansion and contraction with temperature fluctuations. This constant pressure builds up stress within the glass, eventually leading to a shattering event. Think of it like squeezing a balloon too tightly – eventually, it will pop.

4. Spontaneous Glass Breakage

This is a rarer occurrence, but it’s still important to be aware of. What causes glass to shatter by itself? If there are imperfections during the manufacturing process, like tiny nickel sulfide inclusions, they can be trapped within the glass. Over time, these inclusions can slowly expand due to internal stresses or temperature changes. If the inclusion is located in the center tension zone of the tempered glass (the area most susceptible to stress), the built-up pressure can become too much for the glass to handle and cause it to shatter unexpectedly.

5. Excessive Thermal Stress

Will tempered glass break from heat? Tempered glass can break from heat, but it usually takes extreme temperatures (around 400-500°F) or rapid temperature changes. Normal household heat shouldn’t cause issues. The bigger concern is uneven heating, so avoid placing hot pots directly on a tempered glass cooktop or next to a fireplace.

Tempered Glass Breaking: How Does Tempered Glass Break?

Tempered glass is specifically designed to break in a way that prioritizes safety compared to traditional glass.

Here’s how it works:

Glass Type How It Breaks
Regular Glass When broken, annealed glass shatters into large jagged shards with sharp edges. These shards can cause serious injury if someone comes into contact with them.
Tempered Glass Tempered glass shatters into countless small blunt pieces that are typically cube-shaped or pebble-like with minimal sharp edges. This shattering pattern is a result of the glass tempering process itself.

What Is the Science Behind the Break?

The combination of heat treatment and rapid cooling, i.e. the tempering process, creates internal stress within the glass, with the outer surfaces in compression (squeezed) and the inner core in tension (stretched). When tempered glass breaks due to impact or other factors, it releases this internal stress.

Will Shattered Tempered Glass Fall Out?

When shattered, tempered glass is usually held in place by a frame or setting. This means broken tempered glass shower doors won’t rain down on you. However, in frameless applications like some tabletops or balcony enclosures, shattered tempered glass could fall out entirely.

Can Tempered Glass Cut You If Shattered?

While tempered glass fragments are less likely to cause deep cuts, they can still cause nicks or scrapes if you brush against them. Always be careful around broken pieces and wear gloves when cleaning it up.

How to Prevent Tempered Glass from Shattering?

Based on the breakage reasons from the above, here are some tips to minimize the risk of shattering:

  1. Avoid impacts: This seems obvious, but be mindful of bumps and collisions with your tempered glass.
  2. Installation matters: Ensure proper installation by a professional, especially for frameless designs like shower doors or balcony panels. Uneven stress can increase vulnerability.
  3. Temperature extremes: Sudden temperature changes can cause breakage. Avoid placing hot objects directly on tempered glass surfaces.
  4. Cleaning cautiously: Don’t use abrasive cleaners or scrub excessively, as this can weaken the surface.
  5. Edge of trouble: The edges of tempered glass are most susceptible to chipping or cracks. Consider adding edge protectors for high-traffic areas.

Comparing Tempered Glass & Laminated Glass

Unlike the tempered type, laminated glass, when impacted, cracks but doesn’t shatter and stays in the window or door frame. This is because it’s made with a plastic interlayer sandwiched between two or more glass layers. The heavily damaged glass is held together by the inner layer. This creates a web-like pattern of cracks on the glass surface but prevents it from falling apart or creating dangerous shards.

This feature is particularly beneficial for storefronts, as the laminated glass window or door doesn’t break immediately after an attacker has tried to shatter it.

At Apex Tempered Glass, we can make custom laminated tempered glass so that you can enjoy enhanced safety and aesthetics!

Tempered Glass: Why Choose It?

Tempered glass can shatter, but don’t let that misguide you. It’s a superior choice over regular glass for many reasons, especially when safety is a concern. Here’s why.

1. Safe Shattering

As we explained, while tempered glass can break under too much pressure, it shatters safely. Broken glass of the regular type is worse, as it poses a serious injury risk.

2. Increased Strength

The tempering process makes tempered glass significantly stronger than regular glass. It can withstand greater force from impacts, bumps, and even scratches, making it ideal for everyday use.

3. Enhanced Durability

Tempered glass is more resistant to chipping and breaking compared to regular glass. This translates to a longer lifespan for your glass product, ultimately saving you money on replacements.

4. Heat Resistance

Tempered glass has a higher heat tolerance compared to regular glass. This makes it an ideal choice for applications near heat sources, like oven doors or fireplace surrounds.

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* We serve the Illinois and Milwaukee areas.


Even though tempered glass shatters, it prioritizes safety by breaking into small, harmless pieces. Combined with its impressive strength, durability, and heat resistance, it’s the clear choice for applications where safety and long-lasting performance are essential.

If you’re building a project that demands safety and style, elevate your design with our top-quality glass solutions. At Apex Tempered Glass we proudly serve the Illinois and Milwaukee areas and specialize in manufacturing tempered, laminated, patterned, and frosted glass, as well as low-e glass and insulated glass units – customized to your particular needs. Contact us today and get your perfect glass, starting with a free quote!

Nina Tsoy

Finance And Operations

Nina leads Apex Tempered Glass, a company specializing in manufacturing all types of glass. Known for her strategic expertise and exceptional operational performance, Nina is committed to providing innovative solutions for any glass-related issue.


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