The world through rose colored glass

After the studies in Siena ended, I took the opportunity at hand and decided to visit some other places in Italy. It was on this trip that I ended up in Venice… along with the many bridges and canals, taxi boats and gondolas, there was also the wonderful variety of industry native to Venice, such as lace and glass. Not being much taken with the idea of visiting a lace factory, however exciting that may sound, I took a trip to Murano, the small island known for its beautiful creations in the glass blowing factory. I had previously visited a crystal blowing factory with the other Emory students, but Murano was a new experience for me…. Quite a few purchases into my trip, I realize just how lucrative the industry is and some further inspection told me that much of its appeal lies not just in the glass, but the use of color and gold leaf in the actual glass. From this comes my inspiration to for this blog entry: glass and color.
Just as the art of glass blowing had to develop with knowledge and skill, so too did the use of color in glass evolve over time. Colored glass was an accidental discovery, an inventive fluke deriving from impurities. Dark brown or green glass came from impurities in the sand, such as iron, or from the fire smoke, such as sulfur. This fluke lead to the resourceful use of different minerals or metal salts for coloring. Gold chloride creates ruby glass and to make a glow in the dark glass you would use uranium oxide.
Metals can be used in other ways to color glass. Adding metallic compounds to the glass can cause an iridescent effect. Or if you would like that beautiful gold or silver leaf look to the glass without worrying about the metal oxidizing or wearing away, thin layers of colloidal metals are added to the glass and then coating that with another layer of clear glass.
Most of the colored glasses involve some sort of metal oxide ‘contaminating’ the glass itself, such as iron oxide (green, brown), cobalt oxide (deep blue), manganese oxide (deep amber, amethyst), and antimony oxides (white). A lot of the finer designs, though, have other secrets that have nothing to do with combination chemistry of glass and other compounds, but instead is simply the use of glass layering a beautiful work of brushstroke or similar technique.
So next time you pick up that gorgeous green glass that your friend brought you back from Murano, ask yourself: “Is there any iron in this?”

Cited works:
http://www.sciencedaily.com/releases/2009/06/090617123435.htm
http://chemistry.about.com/cs/inorganic/a/aa032503a.htm