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Find Out How Float Glass Is Produced

Float glass is used in most of our windows, automobiles and TV screens, but that wasn't always the case.

Float glass is made primarily from high quality silica sand to which salt cake, limestone, dolomite, feldspar, soda ash and powdered glass are added to make a batch. It gets its name from the way these raw materials are turned into a sheets of glass. Molten glass is poured from a furnace and "floated" across a pool of molten tin.

Once it reaches the desired thickness and size, the glass is transferred from the molten tin chamber into an oven called a "lehr" where it is carefully cooled at different rates depending on the desired strength.  

 

Glass has been around at least since 3500 BC, but not until the late 1950s did we have glass with the clarity and smooth surface of float glass. In 1959, Sir Alistair Pilkington perfected a revolutionary float glass manufacturing process that is still used in 90% of the flat glass produced today. 

 

Float Glass: The Standard Cooling Process 

The standard process of cooling results in annealed glass. Glass cooled at a faster rate than annealed glass is called heat-strengthened glass, and tempered glass results from an even faster cooling rate producing glass that is four times stronger than annealed glass.

Benefits and Applications

Virtually all of the contemporary flat glass you encounter in your daily life is float glass, which replaced plate glass soon after the float glass process was perfected in 1959. It was adopted for a variety of applications because of its many improvements over plate glass and the efficiency and cost effectiveness of the manufacturing process. 

Float glass

  • allows maximum light transmission for bright interiors
  • can be produced in variety of colors
  • can be produced in range of opacities
  • possesses improved clarity over plate glass
  • has a very smooth surface with virtually no inclusions or internal defects

Float glass is produced for a variety of industries including commercial and residential construction, architecture, solar panels, TVs and retail display accessories. All of these applications benefit from its clarity, ease of maintaining and cleaning and transparency. 

If you want to learn more about float glass and how specially trained glaziers create custom mirrors and glass, call our glass experts at Glass Doctor® at 855-603-1919 for a free, in-person consultation.  

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Sources:

History of Glass:  http://www.historyofglass.com/

How Is Tempered Glass Made?: http://www.scientificamerican.com/article/how-is-tempered-glass-mad/

Float Glass, Properties and Applications: http://www.azom.com/article.aspx?ArticleID=89

Float Glass Manufacturing Video: http://www.pilkington.com/en/us/architects/resource-library/float-glass-process-video