If you have ever needed a cracked windshield or rock chip repair then you might know that the auto glass is very unique. Typically, in vehicles, you’ll find two different types: laminated and tempered. So what’s the difference, and why do these different types matter?
Laminated Auto Glass
This type of glass is what you find frequently in windshields and occasionally in certain other parts on vehicles. This type is composed of two separate layers of glass held together by a layer of lamination which is basically pliable transparent plastic.
This construction is what gives the laminated glass its safety qualities. Impacts on this type of glass can either break the glass, cause a pit in the glass, or do nothing.
Most impacts with hard objects larger than small grains of sand do some sort of damage. If your windshield has no breaks, you may still notice little white specs all over the surface that don’t wash off.
These are usually surface pits which are actually small amounts of missing glass that were carved out during minor impacts from smaller projectiles. These pits are not repairable, but they shouldn’t cause you to worry either.
Pitting is damaged glass, but the layer beneath the pit is still intact. In almost every case, a surface pit will not lead to a crack. However, if a crack starts from somewhere else and intersects with a surface pit, the crack can change direction and sometimes split into multiple cracks. This is because the missing glass from a pit makes that spot slightly weaker than the rest of the glass.
A break in the glass is when the majority of the outer layer of the glass has been compromised. In other words, the damage is much deeper than a surface pit. When there is a break in the glass, the damage usually looks darker from certain viewing angles where the break has occurred. This is because glass is a prism, and the light that passes through a break is refracting between two different edges of two different prisms…representing a break in the glass.
Tempered Auto Glass
Tempered parts are the ones that shatter into thousands of pieces when they break. This type may be used in virtually any piece of glass in vehicles other than windshields.
When a piece of glass is tempered, it takes on very different characteristics. The tempering process gives the smooth flat surfaces of the glass incredible surface tension and therefore strength to withstand impact compared to non-tempered glass. Although these parts are much stronger, when enough force is applied to this surface tension, the glass will still break. When this happens, one small crack causes a chain reaction that spiders into thousands of cracks throughout the glass that continue to spread until they reach an edge. This all happens in a fraction of a second.
Why Use Tempered Glass?
The majority of the pieces that are formed when tempered glass breaks take on a cube-like shape. This shape makes the edges of the broken glass a lot less likely to cut through your skin, but beware of smaller shards that can take on sharper shapes. It’s also easier to enter or exit a vehicle in an emergency by breaking through a tempered part rather than a laminated one. That being said, tempered parts are also the go-to method for breaking into someone’s car to steal valuables. Some manufacturers have started adding laminated parts other than the windshield to their vehicles to help reduce the chance of theft. The trade off is that bypassing the glass in an emergency situation can be much harder and more dangerous.