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Glass In History  

A Look at the History of Automotive Glass

Windshields have gone from "a luxury" to high tech


THE PAST AND THE FUTURE

The first automobile windshields were a luxury, sold as optional equipment to motorists who needed something a little more dashing than goggles. Soon came closed cars, busses and trucks. The demand for vehicle glass rose sharply, and has been climbing ever since.

The first milestone was the acceptance of "wrap-around" glass in cars. By as late as 1919, 9 out of 10 cars had only a one-person top and side curtains. This meant that driving a car was truly a fair-weather endeavor. But ten years later, by 1929, 9 out of 10 cars were now equipped with glass all around, to provide protection from wind, rain, mud splashes, road dust, and flying debris. Driving had now become an all-weather activity, and the era of pleasure driving – to see and, perhaps more important, to be seen – had begun. No longer was the car primarily a means to get from one place to another; it was now an integral part of our social fabric. And the manufacture of glass made several notable changes to support this growing trend. In 1924 the process for plate glass was changed from the "batch" method to a continuous ribbon method making the production of glass much more efficient, reliable and affordable.  Four years later PPG introduced a process to mass produce sheet glass which further improved quality and availability.  These advances significantly improved the vision through the windshields, eliminating much of the distortion that had previously existed and made the product affordable enough to be widely used in the automobile.  The innovations in the glass industry with improved optics and affordable costs, made the widespread use of glass windows in cars practical.   These growing industries nurtured the social acceptance of pleasure driving and the resultant love affair that Americans still have with their cars.

 

INCEPTION OF SAFETY GLASS

Another manufacturing milestone occurred in 1927 when laminated windshields were introduced. Prior to this, windshields were made of common glass, which shattered into sharp shards upon breaking. By laminating a layer of film between two layers of thin glass, safety glass was made possible. PPG introduced Duplate® laminated safety glass in 1928. The film served to hold the glass in place upon breaking, greatly reducing injuries from flying glass. It also provided occupant retention and eliminated cuts that arms and heads received from going through a windshield. The interlayer has improved over the years, as has the quality of the glass, and laminated windshields are found in all cars today. Since 1966, all passenger cars produced in the United States have been equipped with an improved laminated windshield with additional built-in safety. It is designed to withstand about three times the impact velocity of the windshield previously in use.

Though curved windshields appeared as early as 1934, it wasn’t until after World War II that many cars had them. By 1957, nearly all U. S. cars had windshields that curved four ways—not only at the sides but at the top and bottom as well. Curved rear windows, giving more styling freedom, were also introduced.

In the early 1960’s curved side windows began to appear. With them it became possible to include more interior room in car body design. Stylists were able to mold smoother, more continuous body lines. Fabricating techniques were developed to permit drilling of holes in side windows for anchoring and lifting mechanisms. More styling flexibility, and the opportunity to add more built-in safety features resulted.

Tempered safety glass is used in the side and back windows of most automobiles on the road in North America. Today’s manufacturing processes combine the forming of glass to the desired contour along with the tempering process to give the glass its required strength. When tempered glass does reach its strength limit, it breaks into smaller granular fragments with relatively smooth edges to reduce the possibility of injury.

The comfort of motorists has not been neglected as auto glass improves. Most new cars can be bought equipped with tinted windows that absorb the heat of the sun and increase the motoring pleasure of its occupants.

 

Styling and Comfort

As a major glass fabricator for the automotive industry, PPG places continued emphasis on glass process improvements, performance improvements, and new glass products. Automobile stylists continue to expand the areas of windshields, back lights and side windows – 15 to 20 percent of a car’s surface today is glass. The automotive industry uses nearly half a billion square feet of glass a year. And the glass, like the cars it helps make a reality, is constantly improving.

As the glass surfaces in cars became larger, passive solar heat gain became more of a problem. Clear window glass did little to keep the car’s interior from heating up, so solar glasses were developed to absorb some of the infrared, heat-producing part of the solar spectrum. PPG’s first solar glass, Solex® was introduced to the automotive market in 1952. Heat-absorbing green-tint glass, like Solex®, soon became the industry standard. PPG now makes a variety of solar control glasses, with the Sungate® windshield being our top performer. A heat-reflecting coating laminated between the two layers of glass in the windshield effectively blocks 60 percent of the sun’s total energy, keeping the car’s interior cooler. It also blocks damaging ultraviolet radiation, protecting interior fabric materials from deterioration and discoloration. A variation, the Sungate antenna windshield, also provides for full-range AM/FM radio reception, eliminating the need for an exterior mast antenna.

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