If you look around your house, and it’s like mine, you’ll probably notice a very common item. Jars are made out of it, some cups and bowls are made out of it, maybe a few decorations on your shelves. This is what windows are made out of and the screens on tablets and phones. Can you guess what it is? …. If you said glass you are correct! Many household items are made from glass. Sometimes materials like glass are just taken for granted. That means we have them but we don’t really understand how they are made or the history behind them, so we don’t really think much about them. But tonight we’re going to talk about the history of glass. Where it comes from, how it’s made and the many steps through history until it became the glass we know today!
To my surprise, I found out glass has been around for a very long time. It’s funny because I thought it was a more recent invention, but the earliest known man made glass is from 3500 B.C., which is about 5500 years ago! Crazy, right? But even before that a form of glass, called obsidian, was used hundreds of thousands of years ago in the Stone Age. You’ve probably heard of the Stone Age, where early humans lived a very simple life, just barely getting by. It was a hard life. Metals weren’t even invented yet and so basic stones were used as tools. Obsidian was one of those tools. It’s a black, glossy rock that is formed from the lava of volcanoes. Stone age humans used it to cut meat to eat and animal skins for clothes and shelter. It was very sharp, so it was a very popular rock to own! But obsidian was different from later glass, because humans didn’t create it, they just found it lying around volcanoes.
So later, around 3500 B.C. in ancient Egypt and Mesopotamia humans learned to make the first glass. Most of the early glass was not clear like the glass you know today and usually they just used it for jewelry, the beads in necklaces, for example. But later they found ways to shape it into bowls and it continued to be very valuable, because very few people knew how to make glass objects.
Over the years glassmakers became very skilled at their craft and by the time of the Roman Empire, they found ways to make it more clear and transparent. Archeologists have found many glass objects around the world that date back to Roman times, proving they were getting very good at glassmaking. The Romans also became skilled at carving (or etching) in the glass and it was traded all across the Roman empire.
By Medieval Times glassmakers became so good that they were able to create windows of glass and used them to decorate the windows of many churches and cathedrals. A cathedral is a very big church. Often these glass windows were red and blue and green and yellow, many different colors, which is called stained glass. When the light hits these colored windows, it produces a very beautiful effect.
Next, during Renaissance Times one of the best known places for glass making was Murano, Venice in what is now known as Italy. Venice is a city literally built on the water on stilts. Can you believe that!? Venice even has a huge cathedral, or church, built on top of the water. People use boats to travel around the city and bridges over the water to connect the neighborhoods. It’s an amazing place to visit if you ever get the chance.
So the glassmakers of Venice were very good at their work, but glassmaking required hot furnaces so it often started fires. So the city leaders had the idea to move all of the glassmaking to the island of Murano, off the coast of Venice, this way if there was a fire it wouldn’t burn down the rest of the city. Good idea, right? The first glassmakers of Murano became famous for their beautiful glass beads and mirrors. Unlike earlier glass their glass was very clear, similar to the glass you see today. And because they were so good at their job, the Murano glassmakers were paid very well and given lots of privileges in Venice. But one thing they weren’t allowed to do was leave! There were very strict rules about the glassmakers not leaving and starting their own businesses or sharing their ideas with people outside of the city. But even with the rules, some of the glassmakers were able to escape and soon the technique of making glass spread across Europe. If you visit Venice today glassmakers still live and work there and there you can see them at work, creating and shaping their glass in beautiful ways.
If you’ve never seen how glassblowing works, it’s worth finding a video and watching it, but basically one person takes a very long tube called a blowpipe. Then molten glass is heated up on the far end in a very hot furnace. They spin the blowpipe in the furnace, shape it on a metal table, and then begin to blow into the end of the pipe. This expands the hot glass on the end, making it larger. Then it’s put in the furnace again and shaped and blown through the pipe, over and over until it’s the shape and size the maker wants it to be. Finally it’s placed in a kiln until it cools and is ready to be used. Like I said, check out a video about glassblowing sometime, it’s really fascinating.
And what is glass made of? There are different materials used to make glass, which include sand, soda ash, and limestone, but it’s melted at such high temperatures it becomes a liquid that can then be shaped or made flat depending on what the creator plans to make.
So back to the history of glassmaking, in 1674 an English glassmaker named George Ravenscroft invented lead glass, which is also known as crystal, and was a major breakthrough in glassmaking.
And then by the 1900s engineers designed machines to make glass. Do you know what happens when you find ways to build something faster? It takes less time, so it becomes less expensive. During the Industrial Revolution, an inventor named Michael Owen’s created an automatic bottle blowing machine, which could make 2,500 bottles in one hour! Soon even ordinary people were able to own glass and used them for cups, bowls, bottles, windows and in many other ways.
In the 1950s Alastair Pilkington discovered a way to make huge glass sheets by floating molten glass on a metal like tin or lead. This allowed them to create large sheets for windows and is now used widely and known as the Pilkington Process after its creator.
Today glass is created in many different ways, using different chemicals to make it stronger so it breaks less. If you’ve noticed the glass in many phones has become stronger due to these better techniques. This is part of the engineering process. Taking something that works and using new techniques or materials to make it better. That might mean making it faster or making it work better or stronger. That idea applies to your own life. You can take something you like and work at it until you become better and better at it.
So, what do you think about glass? Is it more interesting now? I’ll bet when you see glass next you won’t think about it the same. If you’re like me, you’ll look at it and think “wow, I didn’t know it took SO long to get to the kind of clear glass we use today, and how many inventors and glassmakers it took until they were able to figure it out.”
Next time you see something common, like the lights in your house or the refrigerator or the TV, do some investigating yourself. Find a video or an article and read all about the history of that object. It’s fascinating to find out how we got to the inventions we all know and appreciate now.