The evolution and importance of car windshields in automotive design

The car windshield is a fundamental component of modern vehicles, providing essential visibility for drivers while safeguarding against environmental elements.

While modern drivers may take the car windshield for granted, the history of this component reflects significant advancements in automotive design, marked by continuous innovations aimed at improving safety and comfort for both drivers and passengers.

Early windshields and potential dangers

During the first decade of automotive production in the 1890s, cars were essentially open carriages without any form of glass protection. But as cars became faster and more widely used, the need for a barrier to protect drivers and passengers from wind, road debris, and inclement weather became evident.

The first car windshields debuted near the turn of the 20^th century as an optional add-on for cars.¹ U.S. automobile brand Oldsmobile became the first car manufacturer to make windshields a standard feature in 1915,² and other car manufacturers followed soon after.

These early windshields were far from perfect—they were constructed out of standard plate glass, and their propensity to shatter upon impact could lead to severe injuries for drivers and passengers alike.

Development of laminated glass

Laminated glass is a type of safety glass consisting of two or more glass layers held together with a transparent adhesive interlayer. This interlayer prevents the glass from breaking into large, sharp pieces.

In 1903, French chemist and painter Edouard Benedictus made the accidental discovery that a thin layer of cellulose nitrate can keep glass from shattering when he knocked a bottle off the shelf and the broken pieces held together. While initially he did not think anything more about this curious accident, reports of drivers and passengers harmed by broken glass in cars caused Benedictus to investigate the bottle further, leading him to discover the cellulose nitrate coating the broken pieces. He then used this knowledge to develop an early form of laminated glass.

As reported in an article by Rasmussen,³ Benedictus received a patent for his laminated glass in 1909, three years after fellow inventor John C. Wood of England patented an early form of laminated glass in 1906. However, Wood’s invention languished due to technical difficulties in its fabrication, and so Benedictus’s invention became the basis for the first commercial laminated glass products.

In 1912, Reginald Delpech founded the English Triplex Safety Glass Company to produce laminated glass based on Benedictus’s invention. The production cost of the brand name Triplex glass initially limited its market reach, but the outbreak of World War I in 1914 created significant demand for Triplex glass in military applications, such as airplane and automobile windshields, bulletproof glass for tanks, glass for submarines, battleship-bridge windows, and lenses for gas masks and aviator goggles.³

Advancements in windshield design

Though laminated glass started being used in windshields during World War I, it was not until 1927 that it became a standard feature in cars with the introduction of the Ford Model A.³ This first version of safety glass still had drawbacks, however, as explained by ceramic engineer Fred Dimock in a Model T Ford Forum discussion.⁴

“In medium accidents, the glass broke and the plastic acted like a balloon as the occupant was thrust into it. The result was that the balloon effect acted somewhat like an air bag or cushion as the person hit it,” he explains. “The problem was with more severe accidents, where the broken inner glass acted like a knife and it cut the plastic liner. The occupant was then thrust through the resultant hole, and the edges of the glass shredded him. If the person was unlucky enough to only go part way through the windshield, he was caught in a Chinese finger puzzle and received significant lacerations.”

In the early 1930s, five companies joined forces to research and develop an improved interlayer material for automotive laminated glass. By the end, only DuPont and Monsanto remained as development partners, and their innovative polyvinyl butyral (PVB) resin interlayer had improved visibility and penetration resistance compared to the traditional celluloid interlayer.⁵ PVB is now the most common interlayer used around the world in laminated glass.

Alongside developments in laminated glass, advancements in tempered glass for automobile applications took place. Tempered glass is a type of safety glass that undergoes a thermal or chemical treatment process so that it will break into small, rounded chunks rather than sharp, jagged shards. In 1938, Pittsburgh Plate Glass introduced the tempered glass product Herculite to the automobile market.⁶ Today, tempered glass is mainly used for side and rear windows while laminated glass remains the top choice for windshields.

The 1960s and 1970s marked a pivotal period for the automotive industry, with the introduction of various safety standards and regulations for windshields.⁷ It also saw the rise of value-added glass products for cars. Value-added glass offers additional functionalities beyond basic transparency. Early value-added automotive glass products included tinted windshields for glare reduction and ultraviolet protection. Recently, windshields with in-built sensors are taking value-added glass products to the next level. (Learn more about value-added glass products in “Market demands spur development of innovative value-added glass products.”)

Recycling laminated windshields

Though the use of laminated windshield glass has greatly improved the safety of contemporary vehicles, the polymeric interlayer in this glass complicates the recycling and reuse of end-of-life windshields. Fortunately, more companies are starting to invest time and resources in developing improved recycling schemes for used windshields.

One company working to recycle used windshields is Maltha Glass Recycling, a Netherlands-based subsidiary of waste-to-product company Renewi (Milton Keynes, U.K.). The company recently developed a technology that extracts 99.5% of glass from used windshields while also recovering the binding resin PVB.⁸ This technology enables circularity in the production of new products, which previously would have been disposed of as waste.

In conclusion, the history of car windshields exemplifies the evolution of automotive design. With ongoing advancements in materials and technology, car windshields continue to be a crucial element in ensuring the safety and comfort of both drivers and passengers on the road.

Acknowledgments

The author thanks Kevin Bell, managing director at Maltha Glass Recycling Group (Heijningen, Netherlands), for sharing some of the history surrounding car windshields on his LinkedIn, thus sparking the idea for this article.