Hand Blown Glass Art

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 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.

By: Kelly Wheeler

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Dr Mark Voloshin is an international entrepreneur with business interests as diverse as wine farms, museums and glass manufacturing. His company, The Marvol Group is committed to establishing a successful glass manufacturing industry in Dr Voloshin’s home country of Russia through their holding company Marvol Trading GmbH.