Low-iron glass

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]

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

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".