Historians have discovered that obsidian - natural glass
made within the mouth of a volcano when the intense heat
of an eruption melts sand - was first used by man as tips
for spears.
The oldest examples of glass were in the form of Egyptian
beads, dating from 12,000 BC. It was not until 1500 BC
that the first hollow glass container was made by covering
a sand core with a layer of molten glass.
Glass blowing became the most common way to make glass
containers from the First Century BC. However, the glass
made during this time was highly coloured due to the impurities
of the raw material. It was not until the First Century
AD when colourless glass was produced and then coloured
by the addition of colouring materials.
The secret of glass making came to Britain with the Romans.
However, the skills and technology required to make glass
were closely guarded by the Romans and it was not until
the Roman Empire disintegrated that skills for glass making
spread throughout Europe and the Middle East.
The Venetians, in particular, gained a reputation for
technical skill and artistic ability in the making of
glass bottles and a fair number of the city's craftsmen
left Italy to set up glassworks throughout Europe.
In Britain, there is evidence of a glass industry round
Jarrow and Wearmouth dating back to 680AD, while from
the 13th Century, there is evidence of there having been
a glass industry in the Weald and the afforested area
of Surrey and Sussex around Chiddingford.
A major milestone in the history of glass occurred with
the invention of lead crystal glass by George Ravenscroft.
He attempted to counter the effect of clouding that sometimes
occurred in blown glass by introducing lead to the raw
materials used in the process.
The new glass he created was softer and easier to decorate
and had a higher refractive index, adding to its brilliance
and beauty, and it proved invaluable to the optical industry.
It's thanks to Ravenscroft's invention that optical lenses,
astronomical telescopes, microscopes and the like became
possible.
The modern glass industry only really started to develop
in Britain after the repeal of the Excise Act in 1845
relieved the heavy taxation that had been enforced. Before
that time, excise duties were placed on the amount of
glass melted in a glasshouse and levied continuously from
1745 to 1845.
Joseph Paxton's Crystal Palace at the Great Exhibition
of 1851 marked the beginning of the discovery of glass
as a building material. The revolutionary new building
encouraged the use of glass in public, domestic and horticultural
architecture. Glass manufacturing techniques also improved
with the advancement of science and better technology.
By 1887 glass making developed from traditional mouth
blowing to a semi-automatic process when Ashley introduced
a machine capable of producing 200 bottles per hour in
Castleford, Yorkshire - more than three times quicker
than the previous production methods.
Twenty years later, in 1907, the first fully automated
machine was developed in America by Michael Owens from
major glass manufacturers Owens of Illinois, and used
at its factory in Manchester, Illinois making 2,500 bottles
per hour.
Other developments followed rapidly, but it was not until
the First World War, when Britain became cut off from
essential glass suppliers that glass became part of the
scientific sector. Up until then glass was seen as a craft
rather than a precise science.
Today, glass making is a modern, hi-tech industry operating
in a fiercely competitive global market where quality,
design and service levels are critical to maintaining
market share.
Modern glass plants are capable of making millions of
glass containers a day in many different colours, but
green, brown and clear remain the most popular.
Few of us can imagine modern life without glass. It features
in almost every aspect of our lives - in our homes, our
cars and whenever we sit down to eat or drink. Glass packaging
is used for many products, wines, spirits and beers all
come in glass as do medicines and cosmetics not to mention
numerous foodstuffs.
With increasing consumer concern for the environment,
glass has again come into its own proving to be an ideal
material for recycling. Glass recycling is good news for
the environment. It saves used glass containers being
sent to landfill and less energy is needed to melt recycled
glass than to melt down raw materials, thus saving energy.
Recycling also reduces the need for raw materials to be
quarried thus saving precious resources.
The Future of glass
Glass as a material in its own right will always exist.
But many new applications and manufacturing processes
will involve glass in combination with other materials.
Optical fibres, for example, are currently manufactured
with one or more different coating, which are often plastics.
With the increasing sophistication of opto-electronic
devices, there is an increasing need to combine optical
and electronic devices for many applications such as transmission
of audio, video and data information. Glasses and ceramics,
either alone or composite with other materials, will find
increasing application in biological and medical areas.
Materials such as photochromic, electrochromic and thermochrominc
glasses, which respond to external stimuli, are being
developed with various, sometimes unusual, applications.
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