History of Glass :
Historians have discovered that obsidian -
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 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 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-
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-
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 -
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.
Glass Forming :
Like treacle, glass is fluid at high temperature and its fluidity decreases as the temperature is reduced.
However, unlike water, glass has no specific melting or freezing point but is gradually changed from a solid to a liquid as the temperature is increased. It is this property of ‘variable viscosity’, which is used in forming a mass of glass into articles of beauty or utility.
Modern life just would not be possible without glass, But what is this amazing substance, where does it come from and how is it made?
From the jar that holds the morning marmalade, the mirror in which we brush our teeth, the windows and car windscreen we look through, the computer screen many of us look at every day to the light bulb we switch off last thing at night; glass is around us everyday.
Glass is a combination of sand and other chemicals that are melted together at very high temperatures to form a material that is ideal for a wide range of uses from packaging and construction to fibre optics.
People probably first realised glass was possible when they saw melted sand in the bottom of a fire. Among the earliest users of glass were the ancient Egyptians. They made glass bottles as early as 2000 BC. These were found in the tombs of the pharaohs. About a thousand years later, the Chinese were making coloured glass into imitation gemstones.
A form of glass occurs naturally within the mouth of a volcano when the intense heat of an eruption melts sand to form obsidian. Man first used this as tips for spears.
Today we have mastered the glass making process and can make many different types of glass in many different colours and for many different uses.
Glass is made by melting together several minerals at very high temperatures.
Silica in the form of sand is the main mineral and this is combined with soda ash and melted in a furnace at temperatures of 1700°C. Other chemicals are also added to produce different colours or properties. to produce different colours or properties.
Whilst it is still molten the glass is manipulated to form packaging, car windscreens, glazing or numerous other products. Depending on the end use, the composition of the glass and the rate at which it is allowed to cool will vary, as these two factors are crucial in obtaining the properties the glassmaker is seeking to achieve.
Glass Blowing :
For nearly 2,000 years glass blowing by hand was the main method of forming glass articles. The last few years of the 19th century saw the beginnings of blowing glass by compressed air and the 20th century brought in the revolution of mechanisation, although glass blowing is still carried out by craftsmen today.
For glass blowing, a hollow blowing-
Making Glass Containers by Automatic Process :
Until the second half of the 19th century bottles were made by hand gathering, blowing and finishing the neck. A semi automatic method of bottle making was developed after 1850 but this has since been replaced by the fully automatic process. All bottles and jars are now made automatically by one of two methods -
Flat Glass :
The main flat glass products are for high quality glazing in homes, offices, hotels, shops, vehicles public buildings and glass for horticulture: wired glasses for fire resistance; patterned glass for privacy and decoration; and a wide range of glass for environmental control and energy conservation.
Other uses for flat glass include toughened glass doors, suspended window assemblies, cladding for the exterior of buildings, mirrors and low-
Glass Fibre Manufacture :
There are two main groups of glass fibre products: continuous glass fibre which is used for the reinforcement of plastics, rubber and cement; and glass wool, which is used for thermal insulation and which is produced by the Crown process.
Optical Fibre Manufacture :
Communications are increasingly based on eletro-
Glass Tubing :
Glass tubing is used in many products including scientific instruments, fluorescent lights and many other lighting applications. Glass tubes are made by the Danner Process or the Vello Process.
Automatic Domestic Glassware Production :
Tumblers, wine glasses and pint pots are made using the Westlake machine which was originally developed for blowing bulbs for domestic lamps and radio valves. It has since been adapted for making drinking glasses at a rate of up to 55,000 a day.
Electric Light Bulb Production :
The ribbon machine was developed for the high-
Secondary Processing :
As part of the production process some types of glass are subjected to secondary processing such as annealing, toughening , coating and decorating.
Old sailors were loath to give away their secrets, though. The method of making ships in bottles dates back to the 19th century when clear glass bottles were introduced. Sailors liked modeling, and making small models and ships in bottles did not take up space. Ship's space was at a premium and sailors stored their gear and clothing in a ship's chest, which did not hold much more than an average large suitcase.
Ships in Bottles :
The oldest existing Ships-
Dating back to 1850, Ships-
These old models, however, exude a special and unique charm in spite, or just because, of their simplicity.
Often the sailors chose to copy their own ship and, if in a harbor, also the scene around them was placed in the background. In this way, these models became sources of contemporary history.
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-