History of Glass
From our earliest origins, man has been making use of glass. Historians have discovered that a form of natural glass - obsidian - formed for instance, within the mouth of a volcano as a result of the intense heat of an eruption melting sand - was first used by man as tips for spears.
Archaeologists have found evidence of man-made glass which dates back to 4000 BC; this took the form of glazes used for coating stone beads. 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 around Jarrow and Wearmouth dating back to 680 AD, 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 Ravenscrofts 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 Paxtons 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 coatings, 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.
In this Section
The energy saving from recycling a single bottle will power a 100-watt light bulb for almost an hour or a colour TV for 20 minutes.