By Tony Hughes
Tim Shannon’s colourful Bass Coast Post essay “Rooms with a view” (September 5, 2016), prompted me to tell you a little bit about the wonderful material that fills the windows he describes. According to Tim, “A good window gives consideration to admitting light, permitting view, and supporting our needs and behaviour.”
Tim Shannon’s colourful Bass Coast Post essay “Rooms with a view” (September 5, 2016), prompted me to tell you a little bit about the wonderful material that fills the windows he describes. According to Tim, “A good window gives consideration to admitting light, permitting view, and supporting our needs and behaviour.”
Glass achieves this in many forms, a magnificent material, one that the manufacturer normally does not want you to see or be aware of, one just to keep you safe while enjoying that stunning view, one that most people just take for granted. It provides light, a view, protects us from mother natures’ creatures and most of the elements.
What condition would we be in in a car, bus or train without the protection of glass; or its care and containment of our favourite drink, let alone providing the perfect vessel to enjoy it from?
Glass has been and remains an indispensable part of modern life with no equal.
It is made by melting together naturally-occurring materials, silica sand (eroded quartz), soda ash, an alkaline mineral evaporated from brine deposits and limestone, the fossilised remains of sea creatures. This basic formulation has been used for the last 5000 years, with around 90 per cent of the glass made today still using these materials in varying proportions.
It is “organic” (sort of), 100 per cent fat-free, has no added sugar, is low in salt and has a “Best Before” date of 14 billion years plus.
So what is this product everyone uses, but few people know much about?
It weighs two and a half times more than water, is about half the hardness of a diamond, lets about 85 per cent of visible light through, absorbs (stops) most infra-red and ultra-violet light, resists most acids, is weak in tension and can last as long as the universe exists. It would take a few billion years for just a few atoms in a pane of glass to move at all.
All this means that you should not get sunburnt sitting behind a window and your very expensive, photochromic or equivalent glasses don’t work in the car.
The word glass is comes from the Germanic Latin word “glasum”, for transparent and lustrous.
Scientists describe glass as an amorphous solid at normal temperature. It does not have a crystalline structure as most solids do. As liquids do not have a crystalline structure either, it is also described as a supercooled liquid. Something that is hard and brittle is still called a liquid. This is what gives it the lustrous transparent qualities, because there are no crystal boundaries to muck up the light.
Silica, the main ingredient to form glass, melts (vitrifies or fuses) in the region of 1700 degrees Celsius. The flux soda is added to lower this temperature. Unfortunately, soda makes the glass water soluble, not a good thing in a South Gippsland storm. So the stabilisers limestone and dolomite are added to make the glass durable and long lasting.
A batch of Dandenong float glass is around 74 per cent by weight of silica sand from Lang Lang, the quarry just up the road. Soda ash, imported from the US, is around 17 per cent, with limestone and dolomite from South Australia around 9 per cent. Around 20 per cent of the total weight of material fed into the furnace is recycled glass (cullet), sourced only from within the plant; it is added to help the melt and to get rid of it, a win win situation. The purity and quality of all the raw materials are critical to successful glassmaking; inclusions and bubbles can reap havoc with production and add a lot of unnecessary expense.
Until the open-hearth regenerative furnace was invented in 1856, all flat glass manufacture was in batches, not a continuous operation. This invention enabled a rapid change from a batch process to continuous flow operations where sheet glass ribbons were drawn vertically out of furnaces of molten glass or horizontally for plate and other processes.
The gravity-defying production method imparted some distortion, so sheet glass was unacceptable for high quality applications; it was used for domestic and horticultural glazing. No doubt a few readers will remember the scene through the window going up and down as you turned your head.
Plate glass which produced optically perfect, distortion free glass by grinding and polishing off the distortions to produce parallel surfaces, was costly and literally created mountains of waste. It was used for high quality glass essential for showroom display windows, mirrors or automobiles.
Many people in the industry dreamed of combining the best features of both processes to achieve distortion-free, smooth, brilliant, fire-polished glass continuously. A UK company, Pilkington Brothers Ltd., founded in 1826, was the first to successfully combine all these qualities commercially, thanks to a Cambridge University graduate, Alastair Pilkington (no relation).
It was a very long, expensive and frustrating journey. Every obstacle had to be overcome the hard way, one by one. There was no magic bullet or moments, just plain old inspired, hard, hot work. After seven agonising years, they presented their new development, “float glass”, to the world in 1959. Over 90 per cent of the world’s flat glass is now made using this method.
Pilkington Brothers, whose glass was first used in Australia in 1856, together with ACI formed Pilkington ACI in 1971 to build the first float glass plant in the Southern Hemisphere. It opened in Dandenong in 1974 and is still going strong under the ownership of Viridian.
Modern processing methods provide a huge range of glass products to meet most needs. Glass can be made around five times stronger by toughening, incredibly strong by laminating, given better thermal, acoustic and solar control by double glazing, body tinting or reflective coatings. The range of products now available is enormous.
When you next look outside, take a moment to reflect on a wonderful product that many talented and hardworking people have worked so hard and long on to make invisible. And enjoy the view.
Tony Hughes worked at Pilkington ACI from 1974-98.
What condition would we be in in a car, bus or train without the protection of glass; or its care and containment of our favourite drink, let alone providing the perfect vessel to enjoy it from?
Glass has been and remains an indispensable part of modern life with no equal.
It is made by melting together naturally-occurring materials, silica sand (eroded quartz), soda ash, an alkaline mineral evaporated from brine deposits and limestone, the fossilised remains of sea creatures. This basic formulation has been used for the last 5000 years, with around 90 per cent of the glass made today still using these materials in varying proportions.
It is “organic” (sort of), 100 per cent fat-free, has no added sugar, is low in salt and has a “Best Before” date of 14 billion years plus.
So what is this product everyone uses, but few people know much about?
It weighs two and a half times more than water, is about half the hardness of a diamond, lets about 85 per cent of visible light through, absorbs (stops) most infra-red and ultra-violet light, resists most acids, is weak in tension and can last as long as the universe exists. It would take a few billion years for just a few atoms in a pane of glass to move at all.
All this means that you should not get sunburnt sitting behind a window and your very expensive, photochromic or equivalent glasses don’t work in the car.
The word glass is comes from the Germanic Latin word “glasum”, for transparent and lustrous.
Scientists describe glass as an amorphous solid at normal temperature. It does not have a crystalline structure as most solids do. As liquids do not have a crystalline structure either, it is also described as a supercooled liquid. Something that is hard and brittle is still called a liquid. This is what gives it the lustrous transparent qualities, because there are no crystal boundaries to muck up the light.
Silica, the main ingredient to form glass, melts (vitrifies or fuses) in the region of 1700 degrees Celsius. The flux soda is added to lower this temperature. Unfortunately, soda makes the glass water soluble, not a good thing in a South Gippsland storm. So the stabilisers limestone and dolomite are added to make the glass durable and long lasting.
A batch of Dandenong float glass is around 74 per cent by weight of silica sand from Lang Lang, the quarry just up the road. Soda ash, imported from the US, is around 17 per cent, with limestone and dolomite from South Australia around 9 per cent. Around 20 per cent of the total weight of material fed into the furnace is recycled glass (cullet), sourced only from within the plant; it is added to help the melt and to get rid of it, a win win situation. The purity and quality of all the raw materials are critical to successful glassmaking; inclusions and bubbles can reap havoc with production and add a lot of unnecessary expense.
Until the open-hearth regenerative furnace was invented in 1856, all flat glass manufacture was in batches, not a continuous operation. This invention enabled a rapid change from a batch process to continuous flow operations where sheet glass ribbons were drawn vertically out of furnaces of molten glass or horizontally for plate and other processes.
The gravity-defying production method imparted some distortion, so sheet glass was unacceptable for high quality applications; it was used for domestic and horticultural glazing. No doubt a few readers will remember the scene through the window going up and down as you turned your head.
Plate glass which produced optically perfect, distortion free glass by grinding and polishing off the distortions to produce parallel surfaces, was costly and literally created mountains of waste. It was used for high quality glass essential for showroom display windows, mirrors or automobiles.
Many people in the industry dreamed of combining the best features of both processes to achieve distortion-free, smooth, brilliant, fire-polished glass continuously. A UK company, Pilkington Brothers Ltd., founded in 1826, was the first to successfully combine all these qualities commercially, thanks to a Cambridge University graduate, Alastair Pilkington (no relation).
It was a very long, expensive and frustrating journey. Every obstacle had to be overcome the hard way, one by one. There was no magic bullet or moments, just plain old inspired, hard, hot work. After seven agonising years, they presented their new development, “float glass”, to the world in 1959. Over 90 per cent of the world’s flat glass is now made using this method.
Pilkington Brothers, whose glass was first used in Australia in 1856, together with ACI formed Pilkington ACI in 1971 to build the first float glass plant in the Southern Hemisphere. It opened in Dandenong in 1974 and is still going strong under the ownership of Viridian.
Modern processing methods provide a huge range of glass products to meet most needs. Glass can be made around five times stronger by toughening, incredibly strong by laminating, given better thermal, acoustic and solar control by double glazing, body tinting or reflective coatings. The range of products now available is enormous.
When you next look outside, take a moment to reflect on a wonderful product that many talented and hardworking people have worked so hard and long on to make invisible. And enjoy the view.
Tony Hughes worked at Pilkington ACI from 1974-98.