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Everything You Need to Know About Auto Glass Repair and Replacement

Whether it was broken by a hailstorm, a flying rock, or an accident, damaged glass can make your car undrivable. When can glass be repaired? Does it matter if broken glass is replaced with aftermarket parts? Here’s what you need to know about auto glass repair and replacement.

What is Auto Glass?

Laminated glass is made by sandwiching plastic between two panes of glass and using a combination of pressure and heat to fuse the layers together. The plastic has some flexibility, absorbing shocks from the road and from impacts with gravel and other debris. The plastic used also deflects UV light, protecting the passengers and interior from sun damage. When the glass layers break, the plastic layer keeps it together, preventing shards from separating. This makes it less dangerous if the driver or front passenger hits the windshield in an accident.

This glass is so strong that it’s used as a structural component, providing up to 45% of the vehicle’s structural integrity in front end collisions, and over 60% in rollovers. All cars built since the late 1940s use laminated glass for the windshield, and some new vehicles also use it for the rear glass for added strength.

Tempered glass is made from a single pane that is rapidly heated to temperatures over 1,000°F and then quenched with cold air during production. This causes the glass to cool unevenly, creating tension at the center of the pane. While not as strong as laminated glass, it can withstand 10 times as much force as regular glass. Breaking the glass releases this tension, shattering it into small, rounded pieces that are safer than the jagged edges left behind by regular glass. Tempered glass is used on side windows to protect passengers from glass shards. It’s also found in smartphones, shower doors, refrigerator shelves and any other place that broken glass may present a major safety hazard.

When Can Glass Be Repaired?

If tempered glass is scratched or chipped, it’s almost at the point of complete failure. This type of glass is always replaced.

Laminated glass can be repaired with a clear resin filler. A fresh batch of resin is blended to match current weather and humidity conditions. After cleaning the damaged area, a pressurized syringe pushes the resin into the cracks and crevasses, filling the space. Next, the resin is cured using a UV light, then polished to create a flat, uniform surface. This works well for small cracks, but these repairs have limitations:

Resin can’t restore the strength of the pane, so the glass must be replaced if the crack is on an edge.

Severe pitting and breaks can’t be repaired, including conical “bullseye” impacts over an inch wide and thin “star break” cracks over three inches long.

Repairs can leave a blemish that interferes with the driver’s vision if it’s in their direct line of view. These blemishes also interfere with driving aids and active safety systems if they block a sensor.

Damaged repair resin cannot be fixed. If you get a chip or crack in the same spot twice, the glass will need to be replaced.

OEM vs OEE Replacement Glass

Original equipment manufacturer (OEM) glass is identical to the glass used to build your vehicle. Original equipment equivalent (OEE) glass is made by a third party to meet the same specifications as OEM glass. Since it’s important for safety, auto glass is closely regulated. As a result, OEE glass is indistinguishable from OEM glass aside from the label. Sometimes, it’s even made by the same company that manufactures the OEM.

Windshield glass in new cars includes design features like textured coatings needed for sensors and invisible heating elements. It takes a while for aftermarket manufacturers to replicate these features, so the only replacement option is OEM glass. If your car needs OEM glass to restore your vehicle’s functions and safety, your insurance company will pay for this replacement. Otherwise, you will only be covered for cheaper OEE glass.

Some automakers include copyrighted designs on their windows that OEE manufacturers can’t legally replicate to encourage the purchase of OEM parts. Jeep is famous for this, adding an outline of a rock-crawling SUV to the corners of their windshields. Insurance doesn’t cover these types of replacements since they don’t affect function. However, you can pay the difference for the repair if you want to restore your vehicle’s original appearance.

Complete Collision Repair You Can Trust

When you need autobody work for your car, come to Merton Auto Body. We offer complete collision repair from replacing auto glass to replicating custom paint jobs. Our shop is I-CAR Certified, and our technicians are ASE certified. That means we have the skills and equipment to repair any vehicle, modern or antique. Our shop is between Lisbon and North Lake, just a few miles from Hartland and Pewaukee.