How Stained Glass Windows Are Made
Stained glass is not an art in which the method reveals itself at first glance. Few people looking at a stained glass window realize the long and often tedious process by which the result has been obtained.
First, "stained glass" is a term, which is frequently misunderstood, and does not make clear just how the coloring process is done. Stained glass is glass that is colored throughout its thickness by different chemicals while the glass is in liquid form. For instance, gold is used to make red and cobalt to make blue, etc. At one time, the glass had to be blown, but now it is rolled. The density of the color is determined by how thick or thin the glass is and the thinner the glass, the more light that comes through. By using rollers with rough or smooth surfaces, glass can be given a texture as it is made. The variations of texture let the glass pick up light from different angles, making it even more interesting.
An artist designing a stained glass window must know the style of architecture, the amount of light, and the distance from which the window will be viewed to be able to make an appropriate window. He first paints a small sketch, taking care that the lead divisions are integrated into the design. From this a full-scale drawing will be made and this will be used as a blueprint for making the window.
Diamond or hardened steel wheels are used to cut the glass to fit each of the pieces, which will be fitted together, much as a jigsaw puzzle is done.
In most church windows there are designs on the glass and this is done by an artist, who paints in the details with colored opaque enamel. These pieces are then placed in a furnace and baked to about 2000 degrees so that the enamel becomes a part of the glass. Finally, the pieces of glass are fitted together with H-shaped strips of lead. The joints are soldered and if exposed to the weather, they are sealed with special flexible cement. Since lead is not strong enough to support the weight of a window, bars are placed to reinforce and strengthen the window.