First ever use of the natural glass obsidian.
The oldest finds date back to the Stone Age in circa 7000 B.C.
History and development
Glass is a material with a 9000 year history. Unlike bronze and iron, no epoch has been named after glass. Nevertheless, it is a material with prehistoric beginnings which was later produced in traditional craft and manufacturing establishments, and is now mass produced. Today, glass is a material with vast innovative potential that our everyday lives would be impossible to conceive without.
7000 B.C.
B.C.
3000 B.C.
Commencement of the organised production of natural glass into items of jewellery and small vessels in Egypt.
1500 B.C.
The first hollow glass ointment jars and oil containers were produced in Egypt.
100. B.C.
Invention of the glass blowing pipe, which made it possible to manufacture larger vessels.
Popular items included glass jars, carafes and, in the late antiquity period, drinking glasses. Even thin-walled products in all manner of different shapes could be produced with a blowing pipe.
100 A.D.
The Egyptians discovered how to melt transparent glass.
The quality of the glass was enhanced by the high temperatures, making it possible to produce luxurious glass products with intricate decors.
11th century
Venice evolved into the glassmaking hub of the western world. It enjoyed its heyday between the 15th and 17th centuries.
The first glass maker were called "phiolarii" and they are mentioned in 11th century Venetian registers.
Today, there are only a few authentic Renaissance glass items from Venice still in existence.
11th to 17th century
12th century
Window glass was invented during the Gothic period in the 12th century. Crown glass, which is also known as bull’s eye glass, was developed in Rouen (France) in the year 1330.
It is produced by spinning a bowl-shaped piece of glass (bullion) into a flat disk by centrifugal force. Only the centre piece, which is around 10-15 cm in size, is used as window glass.
1688
First documentation of the glass rolling process in Saint-Gobain. This process involved pouring molten glass onto the rolling table, spreading it out and rolling it to achieve a glass sheet of even thickness.
An advantage of rolling was that 40 by 60 inch glass sheets, which are the ideal dimensions for mirror making, could be manufactured. However, the rolled glass had an uneven surface, which was a problem.
18th century
Development of Baroque cut glass - which gradually replaced Venetian glass - in Germany. The glass featured engraved motifs and introduced the concept of individualised glass products.
The Venetian glassmakers had not mastered the art of glass cutting and engraving. More progressive Baroque cut glass products were engraved with hunting scenes, landscapes and allegorical figures.
1884 Otto Schott developed a glass with new optical properties and used melting experiments as the basis for developing special-purpose glass.
18th to 19th century
1900
Development of a method for glass cylinder production by John Lubbers. The glass cylinders could be made with diameters of up to 80 cm and they were up to 8 m high.
They were then cut along one side and flattened. However, it was a rather laborious process and it was particularly difficult to lay down the cylinder horizontally.
1903
Invention of a machine for automated bottle blowing by Michael J. Owens. The invention considerably speeded up the bottle production process. The Owens machine was first used in Germany in 1908.
1904
Invention of a vertical draw process called the Fourcault process by Emile Fourcault.
Drawn glass had the disadvantage of having a slightly convex surface and "draw marks" indicating the direction from which the glass ribbon has been drawn from the tank.
1917
Development of the Libbey-Owens process by the American Irving W. Colburn. Unlike Fourcault, Colburn didn't use a debiteuse. Instead, the glass was drawn straight out of the tank with a metal “bait”. .
A glass ribbon was drawn vertically from the tank, still soft, for about 70 cm before being bent over a polished steel roller into the horizontal plane and fed into the cooler boxes.
This prevented the draw marks and the uneven surface caused by the debiteuse in the Fourcault process. Colburn's method mechanised the process of glass blowing and increased production output forty-fold.
1923
Belgian inventor Emile Roirant made the first European fully-automated bottle-making machine, which was also suitable for the production of smaller batches.
1970
Automated bottle production technology continued to advance after 1945. The first electronically controlled machines were introduced in 1970.
Present day
Today, it is impossible to imagine a world without glass.
It plays an important role in our everyday lives, in research and science, in modern architecture and in future sectors.
Thanks to state-of-the-art technology and new scientific discoveries, the glass industry is continuously discovering new applications for glass.
Glass production
For every type of glass – from moulded glass, through flat glass to tableware and special glass – there is a specialist glass factory or glassworks. This is because, although the production process is very similar for all glass types, they each have special production process requirements. There are usually six phases in the glass production process: mixing batches of raw materials, melting, refining, forming and cooling, quality inspection, finishing and packaging or palleting.
The first step in the glass making process is the preparation of a batch by mixing the correct quantities of raw materials in a mixer. A conveyor belt then transports the batch to the furnace where it is heated up to a temperature of around 1,200°C to melt it. This combines the raw materials and additives into molten glass.
To ensure that all the gases can escape from the molten glass so that there are no bubbles in the finished product, the molten glass is heated up further to a temperature of between 1,450°C and 1,650°C and a refining agent such as sodium sulphate (Glauber’s salt) or sodium chloride (table salt) is added. The higher temperature and refining agent cause all the gas bubbles to rise to the surface of the molten glass so that it is easier for them to escape. After refining, the molten glass is cooled and transported to the moulding machine. The bottles, car windscreens or special glasses that are produced in this way are then cooled in an annealing oven from around 600°C to 100°C before undergoing detailed quality checks to rule out defects and irregularities. In the next step the glass is finished. Various finishing techniques such as printing or engraving are applied before the products run through a final quality check and are put on pallets ready for shipment.
Batch mixing
After being delivered, the raw materials used to make glass are stored in silos in the batch house. From the silos, they are weighed out in the correct proportions for the product being made into a batch. The batch is then put into mixers where it is mixed as evenly as possible before being transported by conveyor belt or in vats to the furnace and fed into the furnace via feeder machines.
Melting
The batch is heated up in the furnace to temperatures of over 1,200°C and the individual components – sodium oxide, calcium oxide and silicon dioxide (or silica) – combine to form molten glass.
Refining
The molten glass produced in the first melt is reheated to a temperature of between 1,450°C and 1,650°C, depending on its composition. As it melts, the glass releases gases (CO2 from the carbonate raw materials and air), which form bubbles. The higher the temperature, the more these bubbles expand and are able to rise through and escape from the molten glass. This process can be shortened by adding refining agents to the batch. As the temperature rises, the refining agent produces gas bubbles, which remove the smaller bubbles by diffusion. This has the advantage of speeding up the process of larger bubble formation and therefore gas exhaustion, because larger bubbles of gas rise more quickly to the surface. The remaining bubbles are reabsorbed when the molten glass cools.
Forming
After refining, the molten glass is cooled down to forming temperature and fed into the forming machines. The wide range of forming machines that are available reflects the wide range of glass products they are used to make. After forming, most glass products then go into the annealing ovens or lears as they are also known.
Annealing
Different glass objects take different times to anneal. The annealing time depends on the type of glass and its thickness. Generally, glass takes between 30 and 100 minutes to cool. Sometimes slow cooling is necessary for larger glass objects. The process can take up to a year.
Quality inspections
Quality inspections are important in the glass production process because they identify any small defects in the glass or deviations from product specifications. These defective glass containers and products are immediately removed from the production line and remelted.
Finishing, packaging and palleting
There are many different techniques and methods of finishing glass. Glass containers such as bottles can be sprayed, printed, matted or labelled, for example. Ampoules, medicine bottles and prefillable syringe systems are laser coded with a product ID. Sheet glass products can also be finished into mirror, furniture, fire-resistant or UV blocking glass. After a final quality inspection, the glass objects are packaged, palleted and leave the factory.