Toughened glass, also known as tempered glass, is a specially processed safety glass designed to be stronger and more resistant to heat and impact than ordinary glass. It is widely used in homes, offices, commercial buildings, shopfronts, doors, shower screens and other applications where safety and durability are important.
But how is toughened glass actually made?
In this guide, we explain the toughened glass manufacturing process, how it differs from ordinary glass, where it is commonly used, and why choosing the correct glass is important for your property.
What Is Toughened Glass?
Toughened glass is manufactured by heating ordinary glass to a very high temperature and then rapidly cooling it.
This controlled heating and cooling process creates internal stresses within the glass. As a result, toughened glass is considerably stronger than standard annealed glass of the same thickness.
One of its most important safety features is the way it breaks. Instead of producing large, sharp shards like ordinary glass, toughened glass generally breaks into many smaller pieces.
This makes it an important choice for many applications where safety glass is required.
How Is Toughened Glass Made?
The manufacturing process involves several important stages.
1. Cutting the Glass to Size
The first step is to manufacture or select a suitable sheet of float glass and cut it to the required size.
The glass must be cut, drilled and processed before it is toughened.
This is because once glass has been toughened, it generally cannot be cut, drilled or significantly modified without destroying the glass.
For this reason, accurate measurements and specifications are essential before the toughening process begins.
2. Grinding and Polishing the Edges
After cutting, the edges of the glass can be processed to remove sharp edges and imperfections.
Depending on the application, the edges may be ground, polished or otherwise finished.
This is particularly important for glass used in applications such as:
- Glass doors
- Shower screens
- Balustrades
- Shopfronts
- Commercial glazing
- Office partitions
3. Drilling Holes and Making Cut-Outs
If the glass requires holes, notches or cut-outs, these are normally completed before toughening.
For example, shower screen glass may require holes for hinges and fittings, while glass doors may require holes for door hardware.
Once the glass has been toughened, additional drilling or cutting is generally not possible.
4. Heating the Glass
The prepared glass is placed into a specialised tempering furnace.
The glass is heated to approximately 600 to 650°C, depending on the glass type and manufacturing process.
At this stage, the glass becomes extremely hot but remains solid.
The heating must be carefully controlled to ensure the glass reaches the required temperature evenly.
5. Rapid Cooling: The Toughening Process
This is the critical stage.
After heating, the glass is rapidly cooled using controlled blasts of air.
The outside surfaces of the glass cool and harden first, while the centre of the glass cools more slowly.
This creates a controlled pattern of compressive stress on the surfaces and tensile stress within the centre.
These stresses significantly increase the glass’s resistance to impact and thermal stress.
This process is known as thermal tempering.
6. Inspection and Quality Control
After toughening, the glass is inspected to ensure it meets the required specifications.
Manufacturers may check factors such as:
- Dimensions
- Edge quality
- Surface condition
- Flatness
- Optical quality
- Breakage characteristics
- Compliance with applicable standards
The finished product can then be transported and installed.
Why Is Toughened Glass Stronger?
The strength of toughened glass comes from the stresses created during rapid cooling.
The outer surfaces are placed under compression. When an impact occurs, the compressive surface stresses help resist the growth of cracks.
This makes toughened glass substantially stronger against impact and thermal stress than ordinary annealed glass.
However, toughened glass is not unbreakable.
A sufficiently strong impact, damage to the edge or certain defects can still cause it to break.
What Happens When Toughened Glass Breaks?
One of the key advantages of toughened glass is its breakage pattern.
When properly manufactured toughened glass breaks, it generally fractures into numerous small pieces rather than large, sharp shards.
This characteristic can reduce the likelihood of serious cuts compared with ordinary annealed glass.
However, broken toughened glass can still cause injuries, so damaged glass should be treated carefully and replaced by a qualified professional.
Where Is Toughened Glass Used?
Toughened safety glass is commonly used in residential and commercial properties.
Shower Screens
Toughened glass is widely used for shower screens because bathrooms are areas where safety glass is particularly important.
Carlisle Glass can provide custom-designed shower screens, including sliding shower screens and corner-opening configurations for smaller bathrooms.
Glass Doors
Toughened glass can be used in many internal and external glass door applications.
It can provide a modern appearance while offering improved resistance to impact and temperature changes.
Shopfronts
Commercial properties often use safety glass in doors, windows and other glazing applications.
When a commercial glass panel is damaged, the correct replacement glass should be selected based on the application, dimensions and relevant requirements.
Office Partitions
Toughened glass is also commonly used for office partitions and internal glazing.
It can help create open, modern workspaces while maintaining visual separation between areas.
Balustrades and Other Architectural Applications
Depending on the design and applicable requirements, toughened or laminated safety glass may be used for balustrades and other architectural glazing.
The correct glass type depends on the location, design and safety requirements.
Toughened Glass vs Ordinary Glass
The main difference between ordinary float or annealed glass and toughened glass is the manufacturing process.
| Feature | Ordinary Glass | Toughened Glass |
|---|---|---|
| Heat treatment | No | Yes |
| Strength | Standard | Higher |
| Thermal resistance | Lower | Higher |
| Breakage | Larger sharp shards | Small fragmented pieces |
| Cutting after manufacture | Possible | Generally not possible |
| Common safety applications | Limited | Widely used |
The correct glass should always be selected according to the specific application.
Can Toughened Glass Be Cut After It Is Made?
No.
This is one of the most important things to understand about toughened glass.
Once glass has undergone the toughening process, it cannot normally be cut, drilled or reshaped.
Attempting to cut toughened glass can cause the entire sheet to shatter.
If you need a particular size, hole or shape, these requirements must be completed before the glass is toughened.
Does Toughened Glass Break?
Yes. Toughened glass is stronger, but it is not indestructible.
It can break because of:
- Severe impact
- Damage to the glass edge
- Incorrect installation
- Excessive stress
- Certain manufacturing imperfections
- Extreme or uneven thermal conditions
If your toughened glass has broken, avoid touching the broken pieces and arrange for professional glass replacement.
Toughened Glass Repairs and Replacement in Perth
If you need toughened glass replacement in Perth, choosing the correct glass for the application is essential.
At Carlisle Glass, we provide residential and commercial glass repair and replacement services across the Perth metropolitan area.
Our services include:
- Toughened glass replacement
- Commercial glass replacement
- Shopfront glass replacement
- Glass door replacement
- Window glass replacement
- Shower screen glass
- Laminated glass
- Double glazing
- Emergency glass repairs
- Custom glass solutions
We service customers across the Perth metropolitan area, from Yanchep to Mandurah, subject to location and availability.
Need Toughened Glass Replacement in Perth?
Broken or damaged glass can be inconvenient and potentially dangerous.
Whether you need a replacement window, commercial glass panel, shopfront, door or custom shower screen, Carlisle Glass can help identify the appropriate glass solution for your project.
For a glass repair Perth service, contact Carlisle Glass for an obligation-free quote.
Carlisle Glass: Perth Glass Repairs
Carlisle Glass provides professional residential and commercial glass repair and replacement services throughout Perth.
- 24-hour emergency glass repair
- Residential & commercial glazing
- Toughened & laminated safety glass
- Shopfront & commercial glass replacement
- Custom shower screens
- Window and door glass replacement
Contact our team today to discuss your glass replacement requirements and request a quote.
Frequently Asked Questions About Toughened Glass
Is toughened glass the same as tempered glass?
Yes. Toughened glass and tempered glass are different terms commonly used for the same type of heat-treated safety glass.
Is toughened glass stronger than normal glass?
Yes. Toughened glass is significantly stronger than ordinary annealed glass of the same thickness, particularly in resistance to impact and thermal stress.
Can toughened glass be cut?
No. Toughened glass must normally be cut, drilled and shaped before the toughening process.
Is toughened glass safe?
Toughened glass is designed as a safety glazing product. When it breaks, it generally fragments into smaller pieces rather than large sharp shards.
How long does toughened glass last?
Toughened glass can last for many years when correctly manufactured, installed and maintained. Its service life depends on the application, environment, installation and condition of the glass.
Do I need toughened glass for my window or door?
It depends on the location and application. Safety glazing requirements can vary, so the appropriate glass should be determined according to the specific installation and applicable Australian requirements.
Looking for toughened glass Perth services?
Carlisle Glass provides glass repairs, toughened glass replacement, commercial glazing, shower screens and emergency glass replacement across Perth.
Contact Carlisle Glass today for an obligation-free quote.