The history of glass

Glass-making - a skillful art!

In today’s modern times glass is part and parcel of our daily lives and it is actually taken as one of the modern marvels. But few people realise that it is part of human kind’s history and it is actually just as old as civilization. Glass is an inorganic solid material that is usually clear or translucent with different colors. It is hard, brittle, and stands up to the effects of wind, rain or sun. It is formed when certain types of rocks melt as a result of high-temperature occurrences such as volcanic eruptions, lightning strikes or the impact of meteorites, and then cool and solidify rapidly.

Naturally occurring glass has been used since the Stone Age, but it seems the Phoenicians made the first glass as we know it today. There is archaeological evidence that glass beads, seals, and architectural decorations were made as early as from around 2500 B.C.

In central Mesopotamia, the basic raw materials of glass were being used principally to produce glazes on pots and vases. It was even very scientifically - calciferous sand were placed in overheated kiln and then combined with soda to form a coloured glaze on the ceramics. It was mainly Phoenician merchants and sailors who spread this new art along the coasts of the Mediterranean.

The earliest people learned to make colored glass by adding metallic compounds and mineral oxides to produce brilliant hues of red, green, and blue - the colors of gemstones. They even found that clear glass was an excellent refractor of light.

It is believed that the Egyptians after 1500 BC invented the process for producing glass jars from dipping a core mould of compacted sand into molten glass and then turning the mould so that molten glass adhered to it. By the 5th century BC this technology had been taken to Greece.

 The Romans also did much to spread glassmaking technology. With its conquests, trade relations, road building, and effective political and economical administration, the Roman Empire created the conditions for the flourishing of glassworks across Western Europe and the Mediterranean. The use of glass objects and the techniques used for making glass were spread as far as Scandinavia, the British Isles and China. Glass objects began to appear throughout Italy, France, Germany and Switzerland. Roman glass had even been found as far as China, shipped there along the silk routes.

The decline of the Roman Empire slowed the progress in the field of glassmaking. Germanic glassware became less ornate, with craftsmen abandoning or not developing the decorating skills they had acquired. Glass didn't completely go out of use, but it didn't become popular again in the West until its resurgence in the 7th century.

Towards the year 1000 BC, a significant change in European glassmaking techniques took place. It was found that soda glass was replaced by glass made from a much more readily available material: potash obtained from wood ashes. From this point on, northern glass differed significantly from that made in the Mediterranean area, where soda remained in common use.

In the 11^th century Germany devised new ways of making sheet glass by blowing spheres, swinging these out to form cylinders, cutting these while still hot, and then flattening the sheets. This technique was perfected in the 13th century in Venice.

In 1291, glassmaking was transferred from Venice to the island of Murano. This made it easier for the city to keep an eye on what was one of its main assets and thereby ensuring that no glassmaking skills or secrets were exported!

In the 14th century, the glassmaking industry of Italy also reached Altare, near Genoa. Altare was not subject to the strict statutes of Venice or Murano with regard to the exporting of glass working skills. Craftsmen from Altare helped to take the new styles and techniques of Italian glass to other parts of Europe. During the 15th Century, the glassmakers of Murano started using quartz sand and potash made from sea plants to produce particularly pure crystal.

In England a significant development took place. A new glass was patented in the 1600’s; lead crystal. In endeavours to find substitutes for Venetian crystal produced from pure quartz sand and potash, the English used higher proportions of lead oxide instead of potash. The result was a brilliant glass with a high refractive index which was very well suited for deep cutting and engraving

Another progressive invention regarding glassmaking emerged from France in the 1600’s. A process was developed for the production of plate glass, principally for use in mirrors, whose optical qualities had, until then, left much to be desired. The molten glass was poured onto a special table and rolled out flat. After cooling, the plate glass was ground on large round tables by means of rotating cast iron discs and increasingly fine abrasive sands, and then polished using felt disks.  The result was the mirror as we even use till today.

It was only during the latter stages of the Industrial Revolution that mechanical technologies were invented for the mass production of glass. It was especially the Germans who, with their revolutionary inventions who took the manufacturing of glass and the quality thereof beyond the 20^th century.

Although this is only a brief look into the history of glass making, it is sufficient enough to allow us to spare a thought on how glass is made the next time we raise our glasses to make a toast! 

Hendrik