Ancient Glass
Glass is made by melting a particular kind of sand in a fire. This
is sand that has a lot of silica in it. People have been using naturally
occurring glass since the Stone
Age, when they wanted an especially sharp edge on a tool or an
arrowhead. Obsidian is a natural glass which forms when sand shoots
out of a volcano during an eruption and is heated by the hot gases
until it melts into glass. You find it in the Aegean
islands between Greece and Turkey, where there are a lot of volcanoes.
Even in the Stone Age,
people used to sail there specially to get the obsidian.
It wasn't until around 1000 BC that people
began to make glass for themselves. The first glass was little glass
beads, which people used for necklaces. Later they learned to make
strings of glass, which you could wrap around a clay
pot to decorate it. By about 700 BC the
Phoenicians (who
were very good at glass working) could make core-formed glass perfume
bottles. You made a solid bottle-shaped core out of clay, and then
you wrapped lots of these glass strings around it, until it was all
covered in them (kindof like a rubberband ball). Then you let it cool
and scraped out the clay to make a glass bottle.
But this way of making glass bottles took a long time, and so glass
was only used for jewelry and fancy bottles for a long time.
By 300 BC, the knowledge of how to make glass had reached China.
But around 100 BC, the Phoenicians figured
out how to make glass cheaply and easily. They learned to blow glass.
You stick a gob of hot glass onto the end of a long metal
pipe, and you blow through the pipe as if you were blowing up a balloon.
The air makes the gob of glass blow up, just like a balloon. Then
as you blow you can shape the glass with a metal stick. This isn't
easy,but it is a lot easier than the glass-string method!
Medieval glasses
Soon after this, the Phoenicians also figured out how to just blow the glass right into a mold (this is called mold-blown glass). Then you don't even have to shape it yourself, and you can get all sorts of fancy shapes. Glass became cheap enough to replace pottery cups for most people, and was very widely used all over the Roman Empire. There were big centers of glass production not only in Phoenicia but also in modern Köln (northern Germany) and other places around the Roman Empire. Roman glass was exported through West Asia and India as far as China.
Glass production in Europe collapsed with the end of the Roman Empire in the 400's AD. But the Islamic Empire and the Roman Empire in the east continued to use a lot of glass, and glass gradually came back to Europe during the Middle Ages. During the Middle Ages, Venice was a big center of glass manufacturing.
To find out more about ancient and medieval glass, check out these books from Amazon.com or from your library:
How Glass Is Made, by Alan J. Paterson (1985). For kids, but it's really about modern glass technology.
Studies in Ancient Technology: Leather in Antiquity - Sugar and Its Substitutes in Antiquity - Glass, by R. J. Forbes (2nd revised edition 1997). Only part of the book is about glass, but it will tell you everything you need to know about glass in ancient Greece and Rome. By a specialist, for adults.
Early Glass of the Ancient World: 1600 B.C.-A. D. 50, by E. M. Stern (1995). Marianne Stern is the leading world expert on ancient glass.
Roman, Byzantine and Early Medieval Glass: Ernesto Wolf Collection, by E. M. Stern and others (2002). Same expert author as above.
