What Is Cobalt Glass?
Cobalt glass is glass mixed with the mineral cobalt. Cobalt gives glass a deep blue color. The glass was well know from ancient times but became popular in Europe in the 18th and 19th centuries. Cobalt compounds are added to molten glass to make cobalt glass. It remains a popular material for decorative items to this day. Cobalt is also used as an optical filter to filter the yellow colors of iron and to filter sodium contamination from glass.
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History
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The Swedish Chemist George Brandt is given credit for discovering the mineral cobalt. He showed that it was cobalt that gave the blue color to glass. Before this, it was believed that the blue color in glass was because of the mineral Bismuth. In fact early civilizations knew about combining cobalt and glass. Examples of cobalt glass jewelry were found in tombs of the Egyptian pharaohs. Cobalt glass pieces were found in ancient Minoan shipwrecks as early as 2700 B.C. A necklace made of cobalt glass was found in Persia dating back to 2250 B.C. Italian and English Glassmakers were particularly skilled in making decorative items with cobalt glass. The popularity of cobalt glass has survived the tastes of human history and is still available as decorative items and is popular with artists and glassmakers.
Features
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Cobalt is the strongest among coloring oxides. 0.5 percent of cobalt is enough to produce a strong blue color. Iron to manganese is used to mute this deep blue shade. Copper and cobalt are the earliest known blue coloring minerals.
Function
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Cobalt is added to give blue coloring to structural glass. Cobalt glass is popularly used by the pharmaceutical and perfume industries. Chemical pharmaceuticals will be protected from contamination by the cobalt in the glass. Cobalt glass is an attractive packaging for perfumes. Cobalt glass art is still used to make decorative items. Cobalt glass also called Bristol glass is a collector's item available in antique shops. As an optical filter cobalt glass is of great value. 5 to 10 pounds of Cobalt is added per ton of glass to filter the contamination of sodium and to neutralize the yellow tint of iron.
Significance
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Cobalt glass is attractive. It is a medium used by artists through history till today for glass sculpturing. Cobalt glass provides the blue colors of stained glass. The Bristol and Murano glassmakers of Venice use cobalt glass to produce their well known collector's items. Cobalt glass is used to make laboratory equipment. Scientists find different minerals and burning flames of different elements look different through cobalt glass than transparent glass. Cobalt glass is also used in forming the glass water pipes of hookahs.
Effects
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Cobalt is added to crystal to get a dazzling blue effect in the same manner that cobalt is added to a diamond to give the diamond a blue tinge which gives the illusion of a blue jaguar running through the glass. Cobalt is the most constant among minerals in its coloring effect. Cobalt glass changes the color of hydrochloric acid in a mixture of colored positive ions. Cobalt glass has twice the effect of viewing violet and blue colors under a fluorescent lamp.
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