Construction of Stained Glass Windows
The pattern of the design is initially sketched out and the colour of the glass identified for each piece. The small pieces of glass are cut from large sheets of glass using a special hand-held cutter. In some situations, the cut edges may have to be ground down using an abrasive wheel. The pieces are then joined together by lead channelling called "cane". Where the cane forms a joint, its surface must be cleaned, an acid flux applied and then solder (a mixture of tin and lead) is melted onto the joint to fix the pieces together. The whole solder process also has to be repeated on the opposite side of the window. There may be tiny spaces left in the cane and a "wash" of putty/filler is brushed over the window in order to dry and hold each piece of glass firmly.
If the window is expected to be opened, or the fit is very large, or it must go into a door, then reinforcing steel bars may be added. In some of the older windows, this may be a steel rod that is held against the outside of the window by copper wires. Some windows, however, have flattened strips of metal actually inside the cane and are hidden from sight.
In windows where paint/enamel has been applied, special paints were used. Typically, one colour is applied at a time and the glass is then "baked" at high temperatures. This process becomes very time consuming, especially if the glass breaks during the heating or cooling, or the colour turns out to not be correct after the baking process. Some glass has been painted on both sides to help provide greater depth and definition to the picture.