April 18, 2017

Sand and Our Glasses

HourglassWhat Is Glass?
 
As you kick your feet along Perth’s soft and white sandy beaches this summer, spare a thought for the glass maker of old as he shovelled tons of the silica sand into a raging hot furnace.

Processes have been modernised, but basically glass is still sand – a very high quality silica sand to which other materials are added. The resulting mixture is called a batch. Some of the other materials included in the batch are salt cake, limestone, dolomite, feldspar, soda ash and powdered cullet.

Cullet is broken glass. It can be left over from a previous batch or from the edges that remain after a batch of glass has been formed and cut to size. Adding cullet helps the batch melt more easily.

 
 

How Is It Made?

Glass is made by melting and cooling the batch. As the batch cools, it becomes solid without forming crystals. Crystals are three-dimensional building blocks that make a substance internally rigid. The lack of crystals makes glass technically a liquid, or an amorphous solid, but also benefits its transparency.

Much of our window glass is imported, but closer to home, one of the more significant deposits of silica sand in Australia is to be found in South Australia. This pale cream sand is processed here to manufacture colourless container glass for the wine, brewing, food, and soft drink industries.

Sand and Our Glasses was last modified: September 16th, 2013 by Cedric & Rachel