When selecting safety glass for decorative or functional application, your choice boils down to tempered and laminated glass. While both qualify as safety glazing materials and adhere to the safety glazing codes, they’re distinctly different, and these differences determine the application.
Tempered and laminated glass panels are well suited for indoor and outdoor applications where safety is a primary concern.
Dig in as we examine each specialty glass in detail to help you tease out these differences and how they can impact your choice.
Tempered Glass Vs Laminate Glass: Summary
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What is Tempered Glass?
Also known as toughened glass or reinforced glass, tempered glass is safety glass that’s up to 7 times stronger than ordinary glass. The glass undergoes physical or chemical transformations to increase its physical strength and ability to withstand physical impact, extreme temperature, and conditions.
How Is Tempered Glass Made?
The tempered glass manufacturing process entails heating annealed glass in a special tempering oven then rapidly cooling it. The extraordinary cooling procedure gives the tempered glass its massive strength.
Glass is only classified as safety glass if it has a surface compressive stress exceeding 15,000 psi or 100 megapascals. Due to the increased pressure on the surface, safety glass often shatters into small rounded pieces instead of sharp, jiggered shards. Typically, tempered glass shatters at approximately 24,000 psi.
Tempered Glass Vs Ordinary Glass
The compressive surface stress differentiates tempered glass from ordinary or annealed glass. Standard glass has zero internal stress, resulting in tiny microscopic cracks forming on its surface. When tension is applied to the glass, the force of the impact concentrates the tension at the crack’s tip, enabling it to spread throughout the glass.
Consequently, standard glass is fragile and will break into irregular, sharp pieces. In comparison, the high compressive stress on the surface of the tempered glass contains any flaws in the glass and keeps them from spreading or expanding.
Properties of Tempered Glass
- Versatility: Tempered glass comes in different shapes, forms, and styles to meet varied applications.
- Impact resistance: Tempered glass has exceptional impact resistance compared to ordinary glass. It can withstand extreme temperatures and conditions.
- Strength: Tempered glass is 3 to 7 times as strong as annealed glass, making it the perfect choice when human safety is a priority.
- Optical distortion: the tempering process results in optical distortion, so tempered glass isn’t as clear as ordinary glass. Black lines and spots are visible if you look at tempered glass through polarized lenses and imperfections are readily visible on the surface
- Fabrication: Any grinding and cutting must happen before the glass is tempered. Any attempt to tinker with tempered glass leads to fractures.
- Safety: The glass shatters into tiny shards when broken, which makes it a much safer option than ordinary glass for vehicles, construction, appliances etc.
Applications of Tempered Glass
Tempered glass is a versatile product with multiple applications in various industries when safety is a primary concern.
Tempered glass is preferred for applications that require strength, thermal resistance, and safety. Vehicles are a prime example that meets all these conditions:
- They’re subject to constant cooling and heating when parked outdoors (thermal resistance).
- They must resist small impacts from debris on the road (strength).
- The glass might pose a health and safety hazard if it shattered into sharp shards during an accident (safety).
Tempered glass is commonly used in facades and building envelopes in the construction center. It’s also used for unframed assemblies, including frameless glass doors. Tempered glass is trendy for structurally loaded applications and a project where ordinary glass may pose a health hazard to human life.
Building codes require contractors to use tempered or laminated glass in doorways, skylights, elevators, stairways, and emergency access panels.
Some home appliances and furniture have tempered glass parts, such as frameless shower doors, cabinets, and glass tabletops.
Tempered glass products are a staple in bars, restaurants, hotels, and the foodservice industry. Safety glass improves safety standards in the hospitality industry by reducing glass-related incidents. Tempered glassware is specially designed to cook and bake in ovens, microwaves, and other cooking devices.
What is Laminated Glass?
Laminated glass is a layered safety glass that doesn’t shatter into smaller pieces when it’s broken. It’s made by pasting vinyl glue film between two pieces of glass sheets and bonding them together to create a curved or flat glass product. The glass is produced in an autoclave where vinyl sheets bind to the glass under high heat and pressure.
Laminated glass holds together even when shattered because the glass sheets are tightly bonded to the laminating vinyl films. The glass fragments remain bound to the thin film, leaving the surface of the broken glass clean and smooth. It’s considered an excellent safety glass because the broken pieces won’t fall or penetrate the surface to hurt people.
Since laminated glass may use a single or multiple layers of vinyl layers, the number of interlayers depends on the eventual purpose of the glass. The laminating layers are made of various materials, including polyvinyl butyral (PVB), liquid resin, EVA, TPU, or ionoplast polymers. PVB interlayers are primarily used for windshield glazing, while EVA interlayers are a staple in acoustically-dampening window panels.
Because the laminating vinyl layers have high tensile strength, they keep the glass from shattering into large sharp pieces. Laminated glass can be made from tempered glass, annealed glass, or a combination of the two. Float glass, heat-reflecting glass, colored glass, and heat-absorbing glass can also be used to make laminated glass.
Following impact, laminated glass cracks in a unique spider web pattern, especially when the impact isn’t sufficient to pierce through the glass layers. Laminated glass is a versatile product commonly used to manufacture windshield and skylight glazing. It is also used for UV protection, glazing, architecture, photovoltaic, and artistic products.
In hurricane-prone areas, laminated glass is used for hurricane-resistant construction, including windows, storefronts, and curtain walls. This type of safety glass is also used for soundproof windows. It has superior sound suppressing capabilities than ordinary glass of the same thickness.
Characteristics of Laminated Glass
A typical laminated glass layer comprises a 0.38 mm interlayer sandwiched between two 2.5 mm thick glass sheets. The combination creates a single sheet of laminate glass 5.38 mm thick.
Layering multiple laminates allows glass manufacturers to create exceptionally thick and strong laminate glass products. The thickest laminate glass panels may have up to nine laminate layers, making them almost 50 mm thick.
Bulletproof glass is a form of laminated glass made using thermoset EVA, polycarbonates, thermoplastic materials, and layers of laminated glass.
The windshields used on cars are about 6.5 mm thick, while the cockpit windows in airplanes are almost 19 mm thick. Cockpit windows often comprise three layers of 4 mm toughened glass bonded with 2.6 mm PVB layers.
Laminate Glass Safety
Laminate glass differs from other forms of safety glasses due to its post-breakage safety and strength. The interactions between the interlayers and the glass sheets determine the strength of the laminated glass, which is tested for performance during the manufacturing process.
The panels are bent and subjected to impact loading to let the interlayers transfer the shear stress to the glass. The interlayer stiffness determines the panel’s thickness and bending stiffness. The glass is specially made to prevent glass shards from flying allover the place when the product is broken. This type of glass breaks into smaller fragments than standard glass panels.
Tempered Glass Vs Laminated Glass: Which is Best for You?
If strength and breakage resistance are your primary concerns, tempered glass is better. On the other hand, if security, UV protection, and soundproofing are your main concerns, laminated glass is a better choice. Laminated glass, unlike tempered glass, can also be customized, which is why it’s a preferred option for graphic projects and indoor application.