The Difference Between Toughened and Laminated Glass

Glass is a ubiquitous material that’s used in windows, doors, windscreens and partitions. Even though you see glass all the time, you probably don’t think too much about the various types that are out there.

Toughened glass and laminated glass are two commonly used types of glass used for a range of different residential and commercial applications.

If you’re looking to add glass features to your home or your office space, a good glass supplier can help you to understand the pros and cons of both glass types. But we’ll get you started with by taking a brief look at the differences between toughened and laminated glass.

Toughened glass

Toughened glass is manufactured using a process called thermal tempering. This is the reason toughened glass is sometimes referred to as tempered glass.

Tempering involves taking a piece of standard glass and putting it through a furnace. The glass is heated to above its transition temperature so that its crystal state can be altered and the internal structure of the glass begins to change.

Toughened Glass

Once the glass reaches the desired temperature, it is quenched. Quenching is the process of rapidly cooling the surface of the material while leaving the centre relatively hot. This causes the cool surface of the glass to compress while the heated centre expands, creating tensile stress.

The compressive and tensile stresses will counteract each other, creating a balanced internal structure within the glass. This structure is what gives the material its strength.

Properties of toughened glass

A typical piece of toughened glass has a surface compression of 69 MPa, which, in imperial units, is around 10,000 pounds per square inch. This is four to five times more than standard, annealed glass. Simply put, it is very hard to break.

Tempered glass can withstand temperatures of up to 250°C and can resist chemical reactions as well as electric shocks.

Due to the internal stresses in toughened glass, it tends to shatter into small, rounded pieces rather than sharp fragments. This reduces the risk of injury when toughened glass breaks.

Main applications

Because of its strength, toughened glass is often used in high-stress settings. For example, high-rise office buildings, balcony doors and outdoor balustrades are often subject to strong winds and, therefore, require durable materials.

Toughened glass is also used in public facilities like bus stations and telephone booths. The strength of the glass gives such facilities extra protection from vandalism.

Due to its ability to resist heat and chemicals, toughened glass can also be used for cooking appliances such as ovens and microwaves.

Laminated glass

Laminated glass is made by taking two pieces of standard glass and placing an interlayer of plastic or resin in between them. This interlayer is usually made of polyvinyl butyral (PVB), thermoplastic polyurethane (TPU) or ethylene-vinyl acetate (EVA).

Depending on what properties the glass requires, the manufacturer might add more interlayers to the piece. For example, a coloured polyethylene terephthalate (PET) film might be included to tint a car window. In some cases, a manufacturer can add printed images or LEDs to the interlayer.

Laminated Glass

Once the necessary materials have been put together, the piece is then put through a series of rollers. This step removes any pockets of air that remain between the layers.

The piece is then heated so that it becomes a fully bonded (cross-linked) product.

Properties of laminated glass

Though it’s not as tough as tempered glass, laminate glass is still commonly used as a security or safety measure.

When excessive force is applied on laminated glass, the material will crack but it will remain in one piece. This is due to the plastic/resin interlayer. When the glass breaks, this interlayer acts as an ‘adhesive’, holding the broken pieces of glass together.

Laminated glass also has sounding-proofing properties. The number of layers makes it difficult for sound waves to pass through the material. In addition, resins like PVB have vibration-dampening qualities, further reducing the amount of noise that passes through the glass.

Main applications

Laminated glass is most commonly used for vehicle windscreens to ensure that they don’t shatter and injure the driver or passengers. Laminated glass is also commonly used in store fronts. For security reasons, it’s important that storefront glass remains in one piece after it breaks. If the glass remains whole, it will prevent trespassers from entering the store and prevent any in-store goods from getting damaged.

A thicker, modified version of laminated glass is also used in bullet-proof glass. Much like with sound waves, the layers prevent the bullet from completely penetrating the surface.

Both toughened glass and laminated glass have their respective pros and cons. To pick the one that’s right for you, you need to consider your particular requirements. Is sound-proofing important to you? Do you need the glass to remain whole after an incident?

If you need advice with these matters, we recommend consulting a trusted glass supplier. They should be able to advise you on the properties of each glass type and let you know which one will suit your personal needs.

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