You’ve probably watched a movie where a villain shoots the windshield of a car only for the bullet to go through and create a small cracked spot. Or perhaps you’ve witnessed a crash where the car windshield was severely cracked due to the collision but it did not break. In contrast, however, all the car windows were broken and shattered.
Why Is That?
The simple answer is the windshield is built to be more resilient than other car windows to protect the driver and passengers.
A Brief History of Car Windshields
In the beginning, when cars first came on the scene, windshields were made of mundane plate glass. This worked fine for a while when cars were few mostly because they were expensive and owned by the rich. However, it wasn’t until they became widespread and started crashing through reckless driving that the problem with ordinary glass became evident. The glass would shatter into multiple bits, severely injuring the passengers and the nearby pedestrians. If the impact was really strong people would sometimes even go through the glass. Undoubtedly this posed a great safety risk.
In 1903, French chemist Edouard Benedictus, while working in his lab, accidentally dropped one of his cellulose-coated beakers. He noticed that, after the fall, the glass pieces clung together and more or less retained the same shape. Through intensive research and application, he was able to come up with a glass laminate prototype. By laminating the glass he was able to make it several times stronger and more resistant to damage.
Soon after, auto manufacturers started utilizing his invention to strengthen their windshields.
Over time, as technology has continued to evolve, his prototype has been tweaked and improved upon tremendously.
Today, windshields consist of two thin layers of glass with a thin layer of resin called polyvinyl butyral (PVB) holding the layers together.
In the event of an accident, the glass holds on to the resin layer as opposed to shattering into shards and flying all over. This makes it safer for the passengers and everyone near the site.
Other Benefits of Laminated Glass
By including a layer of resin into the glass, windshields can last much longer than they initially did. Their longevity and durability mean car owners can carry out replacements after long periods. The windshield is also able to withstand a wide range of fluctuating temperatures without cracking, a phenomenon that is uncommon to ordinary glass.
The resin in the glass also provides added protection against UV rays. UV rays are responsible for causing a variety of skin cancers and mutations. Finally, laminated glass is relatively inexpensive. This is good news to car owners because they get to spend less on repairs and, in case a full replacement is required, owners don’t have to foot exorbitant costs.
Without a doubt, Edouard Benedictus’ accidental invention has saved millions of lives on and off the road. It laid a solid foundation for the safety glass that’s used in all vehicles today.