Stained Glass Repair Is a Wonderfully Perplexing Combination of Art, Science, and the Magic of Light
Simply said, a repair is not a restoration! A repair simply replaces the glass and there may be other changes. A restoration returns the item to its original condition and this is frequently not possible.
The simplest repairs usually involve replacing a single lite or piece of glass in a window or panel with a close match. If the window or panel is in good condition and the damaged glass is clear, it is easy. If the glass is colored, the shape complex, beveled, painted, or other surface treatments—it gets slightly more difficult to absolutely impossible. I will try to give examples below.
This Stained Glass Mosaic Window
Had been constructed by gluing colored glass to a sheet of clear glass and then filling the voids with a glazing material. The installation of the window was poorly done, leaked, and it failed. This panel has more than 500 pieces of glass some of which are smaller than 1/16 of a square inch. The restoration took a long time, a sash and frame had to be made, and carpentry was involved.