Low-iron glass

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The greenish tint of this float glass is from iron impurities. Low-iron glass does not exhibit this color.

Low-iron glass is a type of high-clarity glass that is made from silica with very low amounts of iron. This low level of iron removes the greenish-blue tint that can be seen especially on larger and thicker sizes of glass.[1] Low-iron glass is used for aquariums, display cases, some windows, and other applications where clarity is desired.[2]

Low-iron glass typically has a ferric oxide content of about 0.01%.[1] Ordinary plate glass has about 10x as much iron content. Low-iron glass is made from low-iron silica sand. In the United States, the primary sources for such sand are in Wisconsin.[3]

Fallingwater, a house designed by Frank Lloyd Wright and built in 1939, was one of the first houses to use low-iron glass for windows.[4]

Low iron glass is widely used in solar panels.

Low-iron glass is sold under various brand names. Guardian Industries calls it "UltraClear" or "Ultrawhite".[5] Pilkington calls it "Optiwhite".[6] Vitro calls it "Starphire".[7] Other brand names include "Starlite", "Krystal Klear", "Diamant" and "Eurowhite".


  1. ^ a b YANG Jing-kai; AN Xue-hui; LIU Yan-li; ZHAO Hong-li (April 2009). "Analysis and Calculation of Melting Performance for the Low-iron Glass". College of Materials Science and Engineering, Yanshan University,Qinhuangdao. Cite journal requires |journal= (help)
  2. ^ Architects, American Institute of; Hedges, Keith E. (2017-04-10). Architectural Graphic Standards. John Wiley & Sons. ISBN 9781119312512.
  3. ^ "Map showing high-purity silica sand of Middle Ordovician age in the Midwestern states". United States Geological Survey. 1979. Cite journal requires |journal= (help)
  4. ^ Patricia Lowry, Patricia (November 17, 2009). "Legacy fund to help Fallingwater windows". Pittsburgh Post-Gazette.
  5. ^ "UltraWhite Low-Iron Glass". Guardian Industries. April 17, 2016.
  6. ^ "Pilkington Optiwhite™". Pilkington. April 17, 2016.
  7. ^ "Starphire Ultra-Clear™ glass". PPG Industries. April 17, 2016.