Saturday, December 31, 2011

How Do They Make Stained Glass Colors?

I'll bet many of you wonder how do they make stained glass colors.

Well, here is a simplified explanation.

Quartz sand or silica, is the main ingredient in stained glass.

The melting point of silica (silicon dioxide) is 1723 C. This is a relatively high melting point which makes silicon dioxide very difficult to melt without the use of additives.

Potash, lime, and soda are normally added to the silica to lower it's melting point and make it easier to work with.

The mixture is brought to temperature in a furnace where other compounds are then added to the mix to give it color.

When silica, potash, lime and soda is brought to temperature and melted, the clear mixture turns to glass when it cools.

Different stained glass colors are made by adding various metallic compounds to the molten glass as it is being heated.
  • Blue glass is made by adding Cobalt Oxide
  • Green glass is made by adding Iron Oxide or various compounds of Copper.
  • Red glass is made by adding Gold Chloride or Selenium Oxide.
  • Yellow glass is made by adding Cadmium Sulfide
  • Blue-Violet glass is made by adding Cobalt Oxide
  • Purple is made by adding Manganese Dioxide
  • Violet is made by adding Nickel Oxide
  • Yellow-Amber is made by adding Sulfur
  • Emerald Green is made by adding Chromic Oxide
  • Fluorescent Yellow, Green is made with Uranium Oxide
  • Amber Brown is made by adding Carbon Oxide
  • Greens and Browns are made by adding Iron Oxide
  • White is made with Antimony Oxides and Tin compounds
Other shades are made by adding various combinations of these compounds during the melting process.

Various copper compounds create the colors Blue, Green and Red and lead compounds are used for Yellow.

There are many different types of stained glass which are made by various manufacturers using their own techniques and formulas.

For instance, Dichroic glass is made by fusing two pieces of glass together, often with a thin metal wafer, glass pieces or other object sandwiched between them.

Because of the additives used to color and form the different types of glass, some colors are easier to cut than others.

Some types of glass are also more difficult to cut than others and will be discussed in future articles.

Now you know how they make stained glass colors.

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