Float glass is made by melting raw materilas consisting of sand, limestone, soda ash, dolomite, iron oxide and salt cake. The raw materials are mixed together and feed into a large furnace that is natural gas or oil fired. The raw materials blend together to form a large pool of molten glass. The molten glass is feed into the float bath (tin bath) through a delivery canal. The amount of glass allowed to pour onto the molten tin is controlled by a refractory gate. The tin bath is preasurized by a mixture of nitrogen & hydrogen to eliminate oxygen to keep the tin from oxidizing. The glass flattens out forming a perfectly smooth glossy surface on both sides with an even thickness of approximately 6mm. Thinner glass is made by stretching the glass ribbon to achieve the proper thickness. Thicker glass is made by not allowing the glass pool to flatten to 6mm. This article refers to the material. ... General Name, Symbol, Number tin, Sn, 50 Chemical series poor metals Group, Period, Block 14, 5, p Appearance silvery lustrous gray Atomic mass 118. ...

As the glass flows down the tin bath, the temperature is gradually reduced until the sheet can be lifted from the tin onto rollers, where it is further cooled gradually so that it anneals without strain and doesn't crack from the change in temperature. Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. ... The word anneal has several meanings: In metallurgy and materials science annealing is a heat treatment wherein the microstructure of a material is altered, causing changes in its properties such as strength and hardness. ...

The nitrogen & hydrogen keeps the tin from oxidizing. Some tin is absorbed into the glass, and with a proper ultraviolet light a sheen can be seen which differentiates the tin from the non-tin side. Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ...

In earlier centuries, window glass was made by blowing either large bottles or large disks. The bottles were cut apart and flattened and then window panes were cut from the large surface. Most glass for windows up to the early 19th century was made from rondels, while most window glass during the 19th century was made using the bottle method (these 'bottles' were 6 to 8 feet (2 to 2.5 m) long and 10 to 14 inches (250 to 350 mm) in diameter). Crown glass is either of two kinds of glass. ... Alternative meaning: Nineteenth Century (periodical) (18th century — 19th century — 20th century — more centuries) As a means of recording the passage of time, the 19th century was that century which lasted from 1801-1900 in the sense of the Gregorian calendar. ...

Alastair Pilkington has been identified by many sources as the inventor of the float glass process even though it was first patented in 1848 by Henry Bessemer, an English engineer. The float glass process was also patented in the United States in 1902 by W. E. Heal and again in 1925 by Hitchcock (a revised version of Heal's patent).

Before the development of float glass, larger sheets of plate glass were made by casting a large puddle of glass on an iron surface, and then grinding and polishing both sides to smooth clarity, a very expensive process. General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ...

Glass of lower quality, sheet glass, was made by drawing upwards from a pool of molten glass a thin sheet, held at the edges by rollers. As it cooled the rising sheet solidified and could then be cut. The two surfaces were less parallel and of lower quality than those of float glass. This process continued for many years after the development of float glass.

Patents

• U.S. Patent 2911759 -- Manufacture of flat glass