What is the history of glass?

By Deb Levy


It may seem like a simple question with it a simple answer, but it’s not. Glass is one of the most versatile—and misunderstood—materials in the world. Glass can be used for everything from windows to “glassphalt”, from eyeglasses to bottles. In fact, lots of materials called glass are actually ceramics and have an entirely different manufacturing process. Here, we discuss glass that is put into buildings and vehicles, which is glass made by the float process. That is why it is generally called float glass. Float glass sometimes is also known as flat glass (though it isn’t always flat), or plate glass.

The ancient Romans made glass by blowing air through a very large cylinder and allowing it to cool, then cutting it with a diamond. The resulting glass was neither clear nor even, but it was good enough to be used in windows of the day.

In 1668, the French company Saint Gobain perfected a “broad glass” method of manufacture that involved blowing long glass cylinders slitting and unrolling them to form a nearly flat rectangle. This glass was then ground and polished on both sides.

By the late 1800s, new additives were mixed in. and glass was now re-heated after manufacture in a special oven, then flattened and affixed to a piece of polished glass which preserved its surface.

In 1871, William Pilkington invented a machine that allowed larger sheets of glass to be made. It was the first of many ingenious glass-related inventions to come from the Pilkington family.

By the early 1900s, most glass was manufactured using the sheet glass method through which a ribbon of glass was drawn from a tank furnace between cooled rollers. It produced less expensive, albeit still imperfect, window glass.

The year 1959 was a game-changer for glass manufacturing. That was the year Sir Alistair Pilkington invented the float glass process. Glass made by the float process is less expensive and more consistent in quality than any other type of process currently available. Today, more than 90 percent of the world’s flat glass is made via the float process.