Stained glass: art & function

Vividly colored stained glass windows in a religious edifice.

Vividly colored stained glass windows in a religious edifice.

The art of making stained glass windows is about 1,000 years old. Traditionally, stained glass was used in churches, synagogues, mosques, and other religious edifices. They were primarily used to tell a story to the lay people that were largely illiterate at the time. 

Today, only about ten percent of stained glass is manufactured for use in religious building. The vast majority of it is now destined for municipal and commercial buildings and private residences. Many times, stained glass transoms or door sidelites are used to accent residential buildings, but stained glass can be used in single-hung and double-hung windows as well.

Stained glass is made when metallic salts are added to the soda ash during the glass manufacturing process. A quick reminder: glass is made by heating sand, lime, and soda ash at a very high temperature. Then the molten glass is annealed, or slowly cooled down.

  • Red glass is made by adding selenium oxide or copper compounds. Gold chloride stabilizes the red color, which is why even today red stained glass is more expensive than other colors.

  • Yellows and ambers are made using sulfur, cadmium sulfide, carbon oxide, or uranium oxide.

  • Green glass is made with iron oxide, uranium oxide, chromic oxide, or copper compounds.

  • Blue and indigo glasses are achieved with cobalt oxide. Copper compounds can also be used to make blues.

  • Violet glass is made using manganese dioxide or nickel oxide.

  • White glass is formed with antimony oxides.

Stained glass can take a modern, geometric form in stationary transoms and sidelites as well as in operational windows and doors.

Stained glass can take a modern, geometric form in stationary transoms and sidelites as well as in operational windows and doors.

A stained glass artist first develops their design—whether it’s a pattern or picture. The design is transferred to a template the size of the window, then again into a black and white format called a cartoon. The cartoon is used to make cutline patterns, which are applied to the pieces of stained glass. The pattern is then cut out with a diamond or steel wheel. 

After the glass is cut, the artist will sometimes apply a vitrifiable paint to the glass to add depth and to strengthen the glass. The painted pieces are kiln-fired to fuse the paint to the glass.

Once all the glass pieces are cut and fired they are laid out on a copy of the cutline pattern and fit together using malleable lead caming with an H-shaped channel to receive the glass. The caming is then soldered together on both sides to make a rigid panel, which is then set into a frame of metal or wood. For large windows, reinforcing rods are used to provide additional structural support for the panels.

Our expert team can help you restore stained glass windows by sourcing vintage glass, entire panels, or design and create new stained glass art for your building.

Historical Windows of New York restored the stained glass transoms in this Brooklyn brownstone.

Historical Windows of New York restored the stained glass transoms in this Brooklyn brownstone.