Automotive Glass: What are the main types?

November 10, 2022
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What’s the first thing that catches your eye about a nice car? Whether it’s the twin-turbocharged engine of a sports car, the four-wheel drive of an offroad truck, or something different, it’s probably not the auto glass. However, the windshield is one of the most important parts of the car as the first and last line of defense against any incidents on the road – from road debris to serious crashes, your windshield is vital for your protection. 

There are two types of automotive glass that are used in car manufacturing – tempered glass and laminated glass. Automotive glass is a special type of glass that is used to make the windshield as well as the side and rear windows of all cars, and they use different types of glass. 

The tempered and laminated glass both have specific uses in the car manufacturing process and as such have different qualities. Read on to learn more about the difference between laminated glass and tempered glass. 

What is Automotive Glass?

Automotive glass, sometimes called auto glass, is a term for the types of glass that have been approved for use in the car manufacturing process. Although both tempered and laminated glass has been used in vehicles since the 1930s, they were not necessary under the law until the formation of the National Highway Traffic Safety Administration. The NHTSA implemented regulations on what types of glass could be used under the Federal Motor Vehicle Safety Standards, which has since grown to include many more guidelines

There are also plenty of specialty coatings that can be bought to customize your driving experience without compromising your safety, allowing for anti-glare or hydrophobic properties. However, both consumers and professionals must be careful when purchasing and installing any modifications. The buyer must ensure that the product and the installer are both reputable, as windshield cracks can cause problems if not dealt with quickly.

Laminated Auto Glass

Laminated automotive glass is the type of glass that is used for a car’s front windshield. It is resistant to flying projectiles and can deflect UV light. The most important difference between laminated auto glass and tempered auto glass is how it breaks. The laminated glass must be able to resist breakage above all else. This becomes important when in a situation where airbags must be deployed. The airbag for the driver explodes out directly towards them, usually from the steering wheel. 

However, for the passenger side, they are released from the dashboard and are designed to bounce off the windshield to the passenger. It must be able to resist the speed and force of this release, as well as ensure that no one flies out of the front of the car during impact. Its strength is also important in supporting the roof in the event of a rollover crash, ensuring that it doesn’t collapse. 

Neither of the types of glass is meant to break into large shards like normal window pane glass. When laminated glass is punctured, it is meant to hold itself together as much as possible to prevent further cuts to the victim of a car accident. This is all due to the chemical makeup of laminated glass and the process it undergoes during production. Laminated glass is made with two pieces of glass that are separated by a layer of polyvinyl butyral (PVB), a resin used for strong binding. They are then sealed with pressure and heat, a dual action that bonds the PVB and the glass. Because of these bonds, the windshield is much less likely to shatter, and if it does, it is less likely to injure the driver or any passengers. 

Tempered Auto Glass

Tempered automotive glass is the glass that makes up the side and rear windows of a vehicle. It is similarly resistant to flying projectiles like laminated glass and is five to ten times stronger than regular glass. The tempering process is done by heating and rapidly cooling the glass back to room temperature. This quick temperature change is uneven due to the thickness of the glass, with the surface cooling quicker than the center. The surface of the glass contracts into itself, causing compressive stress. At the same time, the center that is still hot expands from the heat, causing tensile strength. 

Together, they make the center part of the glass very strong – similar to the glassblowing phenomenon of the Prince Ruperts Drop, a glass bead with a long tail shaped like an elongated teardrop. The head of this teardrop is extremely hardy, surviving even being smashed with a glass hammer, while the tail is very delicate. If the tail is snapped between two fingers, the whole piece shatters. In this same way, tempered glass is very strong in the center but incredibly fragile around the edges. For this reason, the glass for car windows is usually sanded down prior to installation, to reduce the number of weak spots. 

In the event that the windows do get punctured, they are designed to shatter into small, dull pieces – preventing cuts on passengers. Why are windows made of tempered glass at all, when they could stay together like the windshield? One of the main reasons why car manufacturers want the windows to be able to break is because windows function as emergency exits if a car door is wedged shut. In the event of a rolled car or an accident that causes it to be submerged, doors may become warped or unable to open due to the pressure vacuum. Breaking the side windows is one way to get out, and there exist a few emergency escape tools that are used during these situations. 

How To Care for Automotive Glass

To clean the auto glass of your windshield, it is recommended to use non-ammonia cleaners and soft cotton or microfiber towels, as they will help remove dirt and grime without causing any streaks. Ammonia-based cleaners can damage your car’s interior upholstery and ruin any coatings or tints on the windshield. You should also check your windshield wipers regularly, as they can turn brittle with age and lead to scratching on the windshield. 

If your windshield does get chipped, it’s not the end of the world. If it is only minor damage, a windshield crack can be fixed without requiring an entire replacement. However, it must be dealt with quickly, because even a small chip can grow quickly and become impossible to repair. They can be repaired using windshield repair kits, although these will not be effective if the damage is a spiderwebbed puncture or a long crack. These DIY kits work by filling the gap with a resin that hardens into a clear, glass-like substance. Make sure to follow all instructions if attempting a DIY windshield repair fix. Professional glass repair technicians can also help fix a windshield if the kit is not enough, or if you are hesitant to do it yourself. They will examine the damage and let you know if you need a full replacement or not. 

Care is always required when dealing with heavy machinery like cars, which travel at high speeds. Checking your inventory and suppliers is a must, but it can be a difficult and complex process. A better all-in-one tool that can help the glass shop stay efficient and organized is the Elmo Anywhere software.

For professionals who are having trouble finding the correct windshield match for a car, the Elmo Anywhere point-of-sale payment software has an add-on for Glass Match Look-up for an extra $1 a month or check out a full price break-down of the Elmo Anywhere software for more details.