What is Glass? A Brief History of Glass

Glass is one of the most versatile – and most misunderstood – materials used in the world. Glass can be used for everything from eyeglasses to bottles, windows to the ‘glassphalt’ you find on the road. Many products called “glass” are actually ceramics and have entirely different manufacturing process than the glass we discuss in this article. Glass that is put into buildings or automobiles, in windows or table tops is usually called flat-, float-, window or plate glass. So exactly what is glass?

What Is The History of Glass?

The ancient Romans made flat glass by rolling out hot glass on a smooth surface. The resulting glass was neither clear nor even, but it was good enough to use in windows of the day. In fact, glass was quite a luxury at the time and only the nobility could afford it. By 1668, the French company Saint-Gobain had perfected a “broad glass” method of manufacture that involved blowing long glass cylinders, slitting them and unrolling them to form an almost-flat rectangle. This plate glass was then ground and polished on both sides.

How Glass Was Made in the 1800s

By the late 1800s, glass was being made by blowing a very large cylinder and allowing it to cool before it was cut with a diamond. After being reheated in a special oven, it was flattened and affixed to piece of polished glass which preserved its surface. In 1871, a gentleman named William Pilkington invented a machine that allowed larger sheets of glass to be made. It was the first of a number of marvelous glass-related inventions to come from the Pilkington family.

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.

Glass In Ancient Rome

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.

Glass Production in the 1600s-1800s

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.

Glass in the 1900s

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 a less expensive, albeit imperfect window.

Innovations In The Glass Industry: The Float Glass Process

Manufacturing processes did not change much until 1959 when another Pilkington by the name of Sir Alistar invented the float glass process. It changed glass manufacturing forever. In the float glass process, a continuous strip of molten glass at approximately 1000 degrees centigrade is poured continuously from the furnace onto a large shallow bath of molten metal, usually tin.

The glass floats and cools on the tin and spreads out to form a flat surface. The speed at which the controlling glass ribbon is drawn determines the thickness of the glass. Glass is much less expensive to produce via the flat process than any other type of process. Today more than 90 percent of the world’s flat glass is made via the float process.

Float glass is very versatile as well. Add silver backing to it and you have created a mirror, heat and then cool the glass very quickly in a special oven and you have made tempered glass. Your windshield is really a “glass sandwich” called laminate glass, made of two pieces of float glass with a plastic interlayer between them. And if you seal two pieces of glass with an airspace between them, you have created insulating glass.

Learn more about the Float Glass Process today.

Glass.com: The Glass Experts

Glass.com is a full-service web and information portal that provides glass information and services nationwide. Whether it be auto glass replacement or custom glass furniture, Glass.com is here to connect you to the experts you need to get your job done today!

Seeing how sleek and polished glass windows of today are, it’s very hard to imagine a point in time when they were crudely made or even completely absent. The glass windows of today are clear, fortified, and even help us to save on energy costs. But before humanity was able to reap the benefits of modern glass windows, glass windows used to look very different. For example, the image below is called crown glass, a product of one of the earliest methods of creating glass windows. There was no way to properly enjoy a clear, crisp view looking out from this type of glass! Crown glass is also not as strong or as safe as the glass windows of today. This just goes to show how far along we’ve come in the development of glass windows.  

In this article, we will take some time to look back and appreciate the phases in the invention of glass windows that have led to the refinement of modern glass windows of today. So sit back, relax, and let’s get started on this historical journey!

The First-Ever Glass was Black and Volcanic

Glass windows history traces far back to the prehistoric times when glass was first discovered in nature. However, this glass isn’t the clear, transparent type of glass that we’re used to. The prehistoric people used naturally-occurring volcanic glass such as obsidian to fashion weapons like knives and arrowheads, as well as jewelry and money.

The Earliest Glass Manufacturing Started at 3500 BC

According to archaeological evidence, the first man-made glass surfaced at 3500 BC in the regions of Eastern Mesopotamia and Egypt. The ancient glass industry had its ups and downs but eventually, this region of the world (along with some surrounding areas) would become the very first centers for glass manufacturing for 500 years.

Understandably, manufacturing glass used to be a slow and difficult process due to small glass melting furnaces and its insufficient heat. But this changed when Syrian craftsmen introduced the blowpipe. This discovery made the process faster, easier, and cheaper.

Back then, the idea of glass windows was not yet conceived and glass was used mostly for making vessels and jewelry.  

The Earliest Glass Manufacturing Started at 3500 BC

According to archaeological evidence, the first man-made glass surfaced at 3500 BC in the regions of Eastern Mesopotamia and Egypt. The ancient glass industry had its ups and downs but eventually, this region of the world (along with some surrounding areas) would become the very first centers for glass manufacturing for 500 years.

Understandably, manufacturing glass used to be a slow and difficult process due to small glass melting furnaces and its insufficient heat. But this changed when Syrian craftsmen introduced the blowpipe. This discovery made the process faster, easier, and cheaper.

Back then, the idea of glass windows was not yet conceived and glass was used mostly for making vessels and jewelry.  

Glass Production Spreads to Rome

The art of glass production made its way to Rome and its colonies. And by the end of the 1st century AD, manufacturing glass was refined and done at scale - to a point that glass became a commonly-available material in the Roman world.  

It was also during this period that Romans were the first to make window glass panes. This early type of window glass was of uneven thickness and was not see-through like modern glass but it allowed some light to pass through.

Stained Glass Gains Popularity Across Europe

During the 4th century, Christians started to build the early churches as Christianity began to spread throughout Europe. In building these churches, stained glass was used for the windows to create beautiful biblical images, thereby making stained glass a dominant art form of this millennium.

The First Window Glass is Manufactured in Britain

During the early 17th century, window glass was first manufactured in Britain. It was during this time that glass windows started to become more popular for homes across the western world.

The manufacturing process was still crude. The process involved the creation of a lengthy balloon of glass that was blown then both ends of this balloon would be removed, leaving behind a cylinder. This cylinder of glass was then split and flattened. During this time, large sheets of glass are not yet made for windows, which is why old glass windows usually had multiple panes of glass that were fastened together with bars.

Large sheets of glass were only made possible by the float process which comes way later in the glass windows’ historical timeline.

The First Glass Factory Opens in America

After some time, the first glass factory was opened in Jamestown, Virginia. The manufacturing process was still relatively the same, consisting of a bubble of glass that was flattened and reheated before being cut into shapes. This was, however, a cheaper and more efficient to make window glass at the time.

The Development of Crown Glass

Crown glass is a pivotal discovery and was introduced to Britain in 1674. The process of making crown glass involves a sphere of molten glass that is blown into a bubble and pierced by a rod. This is then spun into a circular sheet. When it was cooled down, it was cut into panes. Despite its imperfections and ripples, this type of glass it is still finer and clearer than the broad glass of before.  

The Development of Cylinder Sheet Glass

Then, in 1834, a cylinder method of manufacturing quality glass was developed in Germany. This allowed for even larger sheets of glass to be made.

The Development of Drawn Glass

The process of ‘drawing’ glass was introduced by Emile Fourcault in 1904. As the name suggests, the process involves placing a slot in a tank of molten glass and then ‘drawing’ sheets of glass through it, over water-cooled rollers, and straight into a cooling chamber.

Around the same time, Irving Colburn introduced the Colburn machine which made glass in a relatively similar fashion but with the paper-making process as its inspiration. In this machine, the sheet of glass is drawn vertically from the surface of molten glass then gently bent over a roller until it lays horizontally. For both of these processes, the glass had to be ground and polished afterwards.

The Discovery of Laminated Glass

In the year 1903, a French chemist named Edouard Benedictus made the accidental discovery of laminated glass when his glass flask that was coated with plastic cellulose nitrate dropped to the floor and shattered - but did not break. Since this discovery, the process of inserting a thin plastic film between two sheets of glass allowed for more safety with larger windows.  

The Development of Float Glass

In 1959, Alastair Pilkington introduced the process of making float glass. This remains to be the industry standard of making glass today. In this process, the molten glass is poured onto a bed of molten tin. As the molten glass floats on the molten tin, the molten glass spreads out to form a level surface. This process allows for very large panes of distortion-free glass to be made.

Modern Glass Windows

Float glass has come a long way. Now, homeowners have various glass options for their windows. Laminated glass, obscured glass, tempered glass, and Low-E glass are among the options depending on the homeowner’s needs. As one of Canada’s premier manufacturers of glass windows, we at Clera Windows + Doors, are proud to have 41+ years of industry experience, and counting. We continue to adapt and innovate, making sure that our products are of the highest quality for our customers.

Do you need a window for your home or building? Shop at Clera Windows + Doors and avail of our professional window installation service. Contact us today for a free quote!