Many people are surprised to learn that the biggest end use for glass manufactured and imported in this country is not the window panes used to lighten our lives at work and home but rather in the bottles used to package food and drink. Of course when the value rather than the tonnage of the product is considered the position changes rapidly and the much smaller tonnages of specialist flat glass and high quality fibreglass variants quickly gain in importance.
The main constituent of practically all commercial glass is sand. Sand by itself can be fused to produce glass but the temperature at which this can be achieved is about 1700°C. Adding other minerals and chemicals to sand can considerably reduce the melting temperature.
The low cost of the easily available raw materials used and the very high manufacturing temperatures means that it is possible to make large quantities of packages of unsurpassed cleanliness for example for carrying key drugs and other medical supplies. The same properties have in the past allowed traditional glass milk bottles to be re-cleaned many times and the industry has been able to track some bottles with extremely long lives. However we all know that such systems are now under pressure from competing packaging materials with lighter weight characteristics and so the emphasis is now on recycling efficiently and concentrating on high quality food and drink. There is a long standing and understandable association in the public’s mind between weight and quality.
Transparency is a further great virtue of glass and it is notable that although weight saving may for example have been eliminating glass from the car headlamp business in recent years, car windows are still a very, very large market.
The UK glass industry has played a significant role in the development of modern glass technology. In particular Pilkington’s (now part of Nippon Sheet Glass) who were the originators of the Float Glass Process which is now used all over the world in the production of flat glass and has led to the enormous improvements of the last 50 years.
Nowadays recycled glass from bottle banks or kerbside collections, known as cullet, is used to make new glass. Using cullet has many environmental benefits, it preserves the countryside by reducing quarrying, and because cullet melts more easily, it saves energy and reduces emissions.
Although the recycled glass may come from manufacturers around the world, it can be used by any glassmaker, as container glass compositions are very similar. It is, however, important that glass colours are not mixed and that the cullet is free from impurities, especially metals and ceramics.
Glass has been made for thousands of years but only since the Industrial Revolution has it become available to everybody. It is still being developed and is proving to be one of the key products which we encounter in our everyday lives and is now literally irreplaceable in the communication systems which drive our modern world.