This 1800s stained glass panel is a treasure. I do not think anyone cleaned it for at least 100 years. Two hundred years ago, glassmakers began with clear panes that were painted with oxides and minerals and then fired in a kiln hoping for the stain to stick to the clear glass panes. You must be extremely careful cleaning these unstable panels as the stain can chip off.
Glass makers were not as knowledgeable then as we are today. One was trained in “reading the flame” to know how long to leave the glass in a wood or gas-fired environment. Today we have electric kilns and temperature controls so we know exactly how long to fire the glass.
We repaired 25 broken sections on this stained glass panel.