The History Of Glass

History of Glass The history of glassmaking can be traced back to 3500 BCE In its earliest form, Glass was made from impure ingredients. This resulted in a green tint. It took few thousand years before glass gained enough clarity and transparency that’s required for window panes. However, in time, several compounds were introduced to create a range of colours. This variation mimicked precious and semi-precious stones. Glass was "core formed" or "rod formed". Core formed objects comprised moulding molten glass around a removable centre, usually a combination of dung and clay mixed with water. For the rod forming technique, beads and other small items were made by manipulating a glob of molten glass on a long rod which was thrust into a kiln until the glass was malleable. Originally glass was spun into glass "discs". The centre part where it was connected was consider waste and called "the Pig" This was the cheapest part available and virtually discarded. The poor would therefore have windows made up of these made into a larger pane by joining them with lead "H" section, now known as "came". Glass, due to the way it was made with the centre piece needing to be cut out, could only be made in small pieces. This will probably be the reason old houses in Tudor Times only had small windows. In the late 17th century, the English discovered that adding lead oxide to the glass process resulted in a substance which was solid, heavy and durable. Also at this time, the French perfected grinding and polishing techniques and produced the first plate glass, but only the rich could afford it. Then, in the 1700s, there was a revolution in glass production in England . Compressed air technology created flatter, better glass panes. Cooling air was blown into a large glass cylinder in controlled amounts. This cylinder was then slit lengthwise. It was reheated and allowed to flatten under its own weight. Large, relatively inexpensive lites (panes) of glass became available and by 1860 flat glass prices had dropped, making glass affordable in all building construction. In the 1820s, a hand-operated machine ended the practice of blowing individual bottles, glasses and flasks. The 1870s saw the first semi-automatic bottle machines. Plate glass production expanded as water power, then steam, and then electricity made grinding and polishing faster and easier. By the 1860s, offices and commercial buildings were outfitted with plate glass. In the 19th Century, machinery that rolled glass speeded up the manufacturing process. The glass was pushed through two rollers and emerged as a flat sheet onto a steel table. The glass sheets annealed (cooled) slowly on layers of shelves, then were cut. The first wired glass was made in the 1890s Float glass forms the core of glass production tioday. A sheet of glass made by floating molten glass on a bed of molten metal, typically tin, although lead and various low melting point alloys were used in the past. This method gives the sheet uniform thickness and very flat surfaces, optically perfect. Modern windows are made from float glass. The float glass process is also known as the Pilkington process, named after the British glass manufacturer Pilkington, invented by Alistair Pilkington This became the bed rock of glass manufacturing worldwide and the process is still the one used today. Since then the manufacturing of laminated glass has developed. This is as it sounds, literally bonding two or more sheets of glass together to create either safety, security, bullet and blast resistant, or acoustic glazing. Toughened safety glass is when float glass is heated and cooled in quick succession many times. This changes the molecular structure of the glass giving it massive surface tension. This increases its strength 5 fold and if broken shatters into relatively harmless small pieces. Standard float glass, being a super liquid, not a solid, breaks into shards that can be very dangerous.

For more information on The History Of Glass talk to Glazing Refurbishment Ltd