Architectural glass
Cast glass windows, albeit with poor optical qualities, began to appear in the most important buildings in Rome and the most luxurious villas of Herculaneum and Pompeii.
Hot blown glass was cut open opposite the pipe, then rapidly spun on a table before it could cool.
At the center of a piece of crown glass, a thick remnant of the original blown bottle neck would remain, hence the name "bullseye".
Because the method was imperfect, they kept refining it till 1916 when they felt it was perfect, and opened a glass factory based on the technology the year after.
The glass is taken from the furnace in large iron ladles, which are carried upon slings running on overhead rails; from the ladle the glass is thrown upon the cast-iron bed of a rolling-table; and is rolled into sheet by an iron roller, the process being similar to that employed in making plate-glass, but on a smaller scale.
The sheet thus rolled is roughly trimmed while hot and soft, so as to remove those portions of glass which have been spoiled by immediate contact with the ladle, and the sheet, still soft, is pushed into the open mouth of an annealing tunnel or temperature-controlled oven called a lehr, down which it is carried by a system of rollers.
The pattern is impressed upon the sheet by a printing roller which is brought down upon the glass as it leaves the main rolls while still soft.
The glass floats on the tin, and levels out as it spreads along the bath, giving a smooth face to both sides.
Glass is produced in standard metric thicknesses of 2, 3, 4, 5, 6, 8, 10, 12, 15, 19 and 25 mm, with 10mm being the most popular sizing in the architectural industry.
Molten glass floating on tin in a nitrogen/hydrogen atmosphere will spread out to a thickness of about 6 mm and stop due to surface tension.
Here the glass panels are heated to upward of 600 degrees C and then the surfaces are cooled rapidly with cold air.
It could be highly ornamented; Frank Lloyd Wright created over forty different designs for prism tiles.
[16] Modern architectural prism lighting is generally done with a plastic film applied to ordinary window glass.
Annealed glass breaks into large, jagged shards that can cause serious injury and is considered a hazard in architectural applications.
Building codes in many parts of the world restrict the use of annealed glass in areas where there is a high risk of breakage and injury, for example in bathrooms, door panels, fire exits and at low heights in schools or domestic houses.
When broken, the PVB layer prevents the glass from breaking apart, creating a "spider web" cracking pattern.
Tempered laminated glass is designed to shatter into small pieces, preventing possible injury.
By simply tapping the edge of heat-strengthened glass with a solid object, it is possible to shatter the entire sheet.
Similarly, when the surface of chemically strengthened glass is deeply scratched, this area loses its additional strength.
Electrically heatable glass is a relatively new product, which helps to find solutions while designing buildings and vehicles.
Heatable glass can be used in all kinds of standard glazing systems, made of wood, plastic, aluminum or steel.
A nanometre-scale coating of titanium dioxide on the outer surface of glass introduces two mechanisms which lead to the self-cleaning property.
The reasons for this low thickness are deceptively complex, but the potential insulation is good essentially because there can be no convection or gaseous conduction in a vacuum.
For example, a necessary stage in the manufacture of evacuated glazing is outgassing; that is, heating it to liberate any gases adsorbed on the inner surfaces, which could otherwise later escape and destroy the vacuum.
The high temperatures necessary for outgassing also tend to destroy the highly effective "soft" low-emissivity coatings that are often applied to one or both of the internal surfaces (i.e. the ones facing the air gap) of other forms of modern insulative glazing, in order to prevent loss of heat through infrared radiation.
The task of holding the panes apart is performed by a grid of spacers, which typically consist of small stainless steel discs that are placed around 20 mm apart.
The conduction of heat between the panes, caused by the spacers, tends to limit evacuated glazing's overall insulative effectiveness.
The 2006 IBC references for the 2005 edition of the standard Minimum Design Loads for buildings and other Structures prepared by the American Society of Civil Engineers (ASCE, 2005) for its seismic provisions.
[21] If incorrectly designed, concave surfaces with extensive amounts of glass can act as solar concentrators depending on the angle of the sun, potentially injuring people and damaging property.
