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How Glass is Made

Windows, vases, car windshields, computer screens and picture
frames - everywhere you look it is almost a guarantee that
something in your line of vision will be made of glass. However,
the only time we seem to notice it is if the windows need
cleaning or we drop a wine glass and have to clean up the
shards. Take a minute to think about what life would be like
without this material and then learn a little bit more about
where it comes from and how its made.

When Was Glass First Made?

It is very difficult to pinpoint exactly when the first piece
of glass was manufactured, but archaeological evidence suggests
that it was as far back as the second millennium BC. The
belief is that it was the Mesopotamians who first discovered the
art of glass making and the substance was considered to be
incredibly precious, even comparable to gold. When this art
reached the Egyptians, a method called core-forming was
developed. A core made of clay and dung was moulded into a
particular shape and the molten glass was wrapped around it and
then shaped by being rolled on a flat surface.

It was only by the first century BC that a new method of glass
making was developed and would change the face of glass
production for ever more. Originating somewhere on the
eastern Mediterranean, possibly Syria, a hollow tube was blown
through allowing intricate shapes to be created out of the
molten glass gathered at the end. This method soon became the
favoured one amongst the Romans and its ease made glass products
much more accessible to the common people. After the Roman
Empire fell, the art of glass making lost its momentum in Europe
until the popularity of stained glass arose in the 12th century.
It was from the 17th century onwards that href=http://www.marvol.biz/marvol-management>glass making
progressed the most steadily and the use of furnaces eventually
progressed to the float glass method that we still use
today.

What is Glass Made From?

At its most basic level, glass is a brittle, transparent solid
substance, while more technically, it is an inorganic product
of a fusion process which cools to rigidity without
crystallising. The materials used in making glass vary depending
on the desired function of the end result, for instance thicker
glass or coloured glass requires slightly different materials to
be used in the initial process. Most glass products are however
made up of a core set of basic materials, namely being
sand, soda ash (sodium carbonate), dolomite, limestone and salt
cake (sodium sulfate). The basic aim of any glass maker is to
get the maximum amount of quality glass from the ingredients at
the lowest cost possible.

Different Glass Making Methods Used Today

�Float Glass - This is the glass making process that is
still used today and was pioneered by the British Pilkington
brothers in the 1950s. This method is the most cost-effective
way to make large sheets of glass for windows and doors. It
involves floating the molten glass on a bed of molten tin and as
the glass is left to float unhindered, it is essentially
flattened by gravity and its own weight, leaving the surface
smooth and polished.

�Plate Glass - This used to be the main method for
making large sheets of glass to be used in windows, doors and
windshields before the float glass method was developed. A
complicated twin grinding and polishing process is involved that
is costly as well as wasteful. The long polishing process needed
to give the glass its sheen is time consuming and creates excess
glass shards that can't be reused.

�Recycled Glass - Making recycled glass is a great
energy saver as its uses 40% less energy than the process needed
to make new glass. This is because the crushed glass used in the
process melts at a much lower temperature than the ordinary raw
materials usually used to make glass. Another benefit of
recycled glass is that the materials can be used over and over
again � the glass does not ever wear out.

�Container Glass - This is the type of glass used to
make bottles and jars and is usually made up of soda-lime raw
materials. Created through blowing and pressing techniques, this
is a fairly clean and natural glass making process, meaning that
this type of glass is easily recyclable. This process involves
three steps, the batch house, hot end and cold end. In the batch
house step the raw materials are prepared and mixed, while the
hot end involves the melting of the materials and their
manipulation into the desired shape as well as the cooling
procedures. The cold end involves inspecting the container glass
for any defects, packaging them and labelling them for shipping.

�Fibreglass - This is the other main type of glass
besides sheet glass and container glass and is used mainly for
thermal insulation and optical communication. This glass is made
from exceptionally fine fibres of glass and is often used as a
reinforcing agent. The process to make fibreglass is fairly
complicated and usually starts with the raw materials in solid
form that are then melted and sheared into fibres. The fibres
are then wound into a bobbin and turned into the desired
fibreglass shape.