Glass, by nature, is an inorganic compound and is considered to be a mineral. Glass is clear or translucent with different colors added for decorative and utilitarian reasons and is a hard yet brittle substance.

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It is said that glass was first created around 3000 B.C. during the Bronze Age. There are Egyptian glass beads that date back to 2500 B.C.

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In the 1st century BC glassblowing was invented by glass makers in Syria.

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The first clear glass was made in Venice in the 15th century.  This glass is called “cristallo.” It quickly became heavily exported. "Lead crystal" glass was invented by glass maker George Ravenscroft in 1675. Ravenscroft added lead oxide to Venetian glass to create this form of lead crystal glass.

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The sheet glass drawing machine was patented in 1902 by Irving W Colburn, thus changing the future of glass. From this point on making mass production glass was possible. Windows and sheets of glass of all sizes were then made and distributed.

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In 1904 Michael Owen was granted a patent for the "glass shaping machine." With this machine it was possible to mass produce jars, bottles, and other highly desirable containers for household and industry use.

 

adding color to glass ~

Early glass had color purely by default because of impurities in the sand that was used when making the glass. Iron was one impurity in the sand that would color the glass a dark brown or green. Glass from the 17th century in Europe were commonly these colors. An added benefit was the fact that the colored glass helped keep light out and preserve substances inside bottles as well. The sulfur in the smoke of the burning coal used to melt glass created amber and brown colors.

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As well as natural impurities added to color glass, minerals and pigments are commonly added to change the color. In the glass making process it may also be necessary to remove unwanted color or impurities in order to make a certain color of glass. This process is called "decolorizing" and uses manganese dioxide and cerium oxide. 


~ a list of glass pigments ~


iron oxides ~ greens and browns

manganese oxides ~ deep amber, amethyst, decolorizer

cobalt oxide ~ deep blue

gold chloride ~ ruby red

selenium compounds ~ reds

alexandrite ~ pink / light purple

carbon oxides ~ amber/brown

mix of manganese, cobalt, iron ~ black

antimony oxides, tin compounds ~ white

uranium oxides ~ yellow green with glowing properties

sulfur compounds ~ amber/brown

copper compounds ~ light blue, red

lead with antimony ~ yellow

much of this information was sourced from about.com

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