This was its origin: in a part of Syria which is called Phoenicia, there is a swamp close to
Judaea, around the base of Mt. Carmel, from which the Bellus River arises . . . whose sands are purified from contamination by the torrent's flow. The story is that here a ship of
natron merchants had been shipwrecked; when they were scattered about on the shore preparing food and no stones were at hand for propping up their pots, they brought lumps of natron from the ship. The sand of the shore became mixed with the burning natron and translucent streams of a new liquid flowed forth: and this was the origin of glass.
Saint Isidore of Seville, Etymologies XVI.16. Translation by Charles Witke.
A Quick History of Glass
Glass was first discovered in the area around Persia in 3500 - 3000 BC, and it is the substance you get when you mix
quartz or silica, potash and chalk at high temperatures.
Glass occurs in nature as obsidian, produced by volcanoes, fulgurite,
created when lightening strikes a beach, and tektites which are thought to be
formed when meteorites strike the earth.
Man has used glass from prehistoric times, with both obsidian and fulgurite
being used for tools that needed sharp cutting edges. The thinness of the edge
able to be put onto a glass tool outweighed the brittleness of the tool.
Man began creating glass on purpose in either 7000BCE or 3000BCE in either
Egypt or Assyria and Mesopotamia. The glasses created during these periods
and in these area were coloured.
In the beginning of glass blowing history, a basic glass cup was made by rolling an iron bar into a mix of horse dung and clay to create a mould. You would then wait for the mould to dry. Once the mould was dry, you would dip it into the molten glass. When the glass was cold you could scrape out the horse dung/clay mix and you would have a cup or perfume bottle.
During Egypt's 18th dynasty, around 1500BCE the first glass vessels were
made by attaching a silica paste (the core) to a metal rod which was then dipped into molten glass over and over again,
producing small bottles. During this period glass makers began using glass
threads in the decoration of glass articles.
Between 250 BCE and 100 BCE glass blowing was discovered and became an export
industry in Babylonia. Roman nobility began to use glass drinking
vessels in preference to those made of precious metals, as a status symbol.
By 500CE colored glass windows, and doors made of opalescent glass are known to have existed.
And the first known pictorial windows made of colored glass are known to have
existed by 800CE.
In 1400CE Venetian glass began its 300 year domination of the European glass-making industry,
and in 1600 people realised that if beer were stored in glass bottles it would
undergo a secondary fermentation process which improved its quality. This lead
to the law implemented in England in 1615 that glass makers must use coal
instead of wood... because of heavy deforestation which was occurring
The first true plate glass was produced in 1668 at St. Gobain, France by the
process of blowing a long glass cylinder, slitting it lengthways, and gently
unrolling it to form a rectangle. This was known as the broad glass method,
and was soon abandoned for the crown glass method, where a large sphere, rather
than a cylinder, was blown, cut and flattened.
The split mold was invented in 1821, ending the age of blowing individual vessels such as bottles, glasses and flasks.
William Pilkington, in 1871, invented a machine to manufacture large sheets of
glass using the Crown Glass method. Also that year, a machine was perfected to produce glass bottles in mass quantities.
Carnival Glass was made in the USA between 1908 and 1928.
In 1926 the Sale of Food Act caused the production of the first milk bottles and the first mass organized recycling of glass.
Alistair Pilkington of the Pilkington Glass Company invented the Float Glass process of making flat
glass in 1959. In this process, a continuous strip of molten glass (about 1800 degrees Fahrenheit) is poured from the furnace onto a large shallow bath of molten metal, usually tin. It floats on the tin, spreads out and forms a level surface. After annealing the glass emerges as a 'fire' polished product with virtually parallel surfaces. Today, much of the world's flat glass is made with the Float Glass process. Window glass is made by putting an iron bar vertically into the molten glass and then lifting it up to a height of about 20 metres or more. After that it is cut into suitably sized pieces.
Glass Blowing
Blowing glass is a specialist process and should not be attempted without
the correct tools and knowledge. And here's how you do it :)
What you will need:
- Some glass. Or some silica and soda.
- A vessel to melt the glass (or make it) in.
- A table or bench covered with highly polished steel.
- Various tools for working the glass. Anything which will not be damaged by
the very hot glass is fine.
- A hollow piece of steel long enough to let you avoid bringing your face
too close to the molten glass which will be on the end of it, and short
enough for you to control easily.
- A steel rod of a similar length to the tube.
What you have to do.
- Melt your glass.
- Rotate the hollow steel in the molten glass until you have gathered the
amount of glass you need.
- Blow gently and evenly down the tube, causing the glass to inflate like
a balloon.
- Roll your glass on the table covered with steel to smooth its surface and
even the shape..
- Allow the surface of the glass to cool a little, then use your tools to
help you shape the glass. You can continue inflation during this time.
Applying pressure to one side while blowing into the tube will cause the
glass to inflate more on one side than on the other.
- Transfer your glass to the end of the steel rod, using a blob of molten
glass as glue to hold it there.
- Holding the end of the steel rod, warm the glass in the fire.
- Remove the glass from the heat and continue adding fine detail to the
glass with your tools.
It is possible that the glass will crack unless it is allowed to cool very
slowly. An annealing oven would be an ideal place to let the glass cool over
a period of about 12 hours.