Although the methods for manufacturing glass have been refined to a science, the same basic recipe is used: Melt sand (or silica) with an alkali and lime, add minerals for color, and press the glass to create different textures. A glass artist may also paint glass and reheat it to achieve a certain color or effect.
With the desired picture in mind, the artist selects the glass by color and texture--red for roses, marbled gold for a prince's cape, blue-green for a pasture, rippled glass for a river--then cuts the glass using a paper pattern to create the pieces that will make up the complete picture.
The artist may choose to add a piece of metal or stone to the picture for interest, perhaps stones to decorate a crown, or metal latticework for a garden gate.
The lines you see in a stained glass window are lead or solder. The glass artist wraps each piece of glass with a grooved lead strip, called came, then solders the ends together. Came is then used to join the pieces into sections and the sections into the complete picture. For larger windows, a matrix of concrete, epoxy or plastic may be used instead of lead came.
For smaller windows or intricate designs, copper foil is used instead of came because it is flexible, lightweight and easier to wrap around the pieces of glass. Both the lead came and copper foil are available in different widths to accommodate the thickness of the glass.
Solder is the "glue" that holds the sections together. If the pieces are wrapped in copper foil, the wrapped pieces are laid out to form the complete picture, with a small space between the pieces to form a channel for the solder. With a soldering gun in one hand and solder in the other, the artist drops the molten solder along the channel in a uniform line.
The completed picture is inserted into a wood or metal frame and held in place by weatherproof caulking. The complete picture is now ready to display in a church window or other building to capture the sunlight and make the glass come alive with color.
