Modern windshields are generally made of laminated safety glass, a type of treated glass that is composed of two curved sheets of glass with a layer of plastic laminated between them for added safety and adhered to the window frame. This creates a thicker, stronger window that is considered one of the safest types of glass because it is not easy to break or shatter. Most vehicle windshields are made of laminated glass, which is effective in preventing break-ins due to the effort required to break them. Safety glass is used in all automotive glass and is designed to reduce the likelihood of injury should it break.
Windshields are manufactured from a lamination process, where two pieces of float glass are sandwiched with a thin layer of vinyl between them. This combination of pressure and heat chemically and mechanically bonds the PVB to the glass, creating a thicker, stronger window. When a small object hits a piece of safety glass, usually only the outer layer breaks.
Automatic glassis not made of the same material as glass jars or bottles.
In fact, it is made up of layers of glass and plastic that fuse together. Float glass is used to create laminated glass, which is composed of two pieces of float glass with an interlayer of plastic between them. The resulting glass is much stronger than simple float glass and when broken, it breaks into small pieces instead of large fragments. This type of glass is used in the side and rear windows of the vehicle and gains strength through a rapid heating and cooling process that strengthens the outer surface of the glass and its core.
In 1903, French chemist Edouard Benedictus stumbled upon the secret of shatter-resistant glass when he dropped a glass jar filled with a dry collodion film. This “tempering process” makes glass many times stronger than untempered glass of the same thickness. The inserted layer of PVB allows the glass to absorb energy during an impact and gives it resistance to the penetration of flying projectiles. However, in severe impact situations, the glass “breaks” but usually does not separate because broken pieces generally adhere to the vinyl inner liner.
For windshield replacement, you have the option of selecting a replacement made by a company that makes OEM windshields or aftermarket glass. Ellen Rogers has been involved with the glass industry for nearly 20 years and is the editor of USGlass Magazine and Architects' Guide to Glass magazine. She has seen how automotive glass has evolved over time to become stronger, safer and more adaptable to new vehicles. Laminated safety glass is an important component in automotive safety as it provides protection for both vehicle structure and occupants inside.
It may bend slightly under impact and is less likely to break than normal safety glass.