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Last edited 12 Aug 2021
Glass is a material made from liquid sand. It is an amorphous (non-crystalline) solid that displays a glass transition near its melting point which is around 1,700°C (3,090°F). This means that materials transform from a hard and brittle state into a molten state, or vice versa depending on whether the glass transition temperature is the melting or solidifying point. An amorphous solid has some of the crystalline order of a solid and some of the random molecular structure of a liquid.
 History of plate glass
Plate glass is a type of glass that was first produced in plane form. The earliest successful version of plate glass was manufactured in France in the 17th century. It was an improvement over the cylinder glass or broad glass method, which required the glass maker to swing a bubble of molten glass back and forth whilst blowing, producing an elongated balloon that could be formed into the shape of a cylinder and then flattened into a sheet.
The advance plate glass process was introduced by Louis Lucas de Nehou and Abraham Thevart. It involved casting the molten material onto a metal table and then grinding and polishing the glass by hand.
This technique was automated in the 1800s when a steam engine took over the grinding and polishing process. The process improved again in the early 1900s, when machines were designed to incorporate methods including the Fourcault process, the Bicheroux process and others. Using these methods, plate glass could be manufactured in various weights and thicknesses. It was colourless and had good transparency, which is why it was once commonly used for large picture windows and glass doors.
 Imperfections and distortions
While it was produced with a smooth finish, plate glass was not always entirely flat or parallel. This sometimes produced a slight distortion effect. Once float glass was introduced in the 1950s, plate glass became less popular.
Float glass created large, thin, flat panels from molten glass that were then floated onto a pool of molten metal such as tin. This process produced a very smooth sheet of glass with a highly consistent thickness.
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