A History of Glassmaking
Glass-like substances occur naturally and have been used by humans for generations. The best known is obsidian, produced by the intense heat of volcanoes. Origins of the first manufactured glass are lost in antiquity.
It is thought that seagoing Mediterranean merchants accidentally combined a form of soda, sand and limestone with their beach campfires and noticed the hard, clear substance left in the ashes.
These basic ingredients are used in glassmaking to this day. Egyptians established the first known glass factory around 1400 BC. By 500AD, the Roman empire had helped to spread glass-making techniques throughout the Mediterranean and beyond, to northern Europe and Britain.
Flat glass was for centuries produced by blowing a large bubble of molten glass at the end of a metal tube. After cutting off the ends and splitting the resultant cylinder in half, the two pieces were softened by reheating and beaten flat on a large stone using a broad wooden paddle.
The blown, cylinder process continued to be developed until in the mid 19th century, cylinders up to 12 metres long were being successfully split.
Alternative processes devised included the ‘crown’ process, which entailed adding a disc to the end of the rod and blowing a glob of molten glass onto the disc. It was then turned with speed by means of the rod, with the resulting centrifugal force spinning a large flat disc.
In the early 20th century, techniques were developed of drawing molten glass to form sheets which were then automatically polished on both sides.
This process met the demand for modern building and automotive glass, but was replaced in 1959 with the Float Glass process.
Ninety per cent of the world’s flat glass is now made by this process. Glass making was established in Australia soon after European settlement, but flat glass manufacture began only in 1935 with the first sheet glass plant in Sydney.