A Gothic window is a picture made of light. Glassmakers colored molten glass with metal oxides: cobalt for blue, copper for green and red, iron or manganese for other colors. They blew it into sheets, which the glazier cut into pieces following a full-size drawing. Painters added faces, folds and lettering with a dark paint made of ground glass and iron oxide, and fired the pieces in a kiln so the paint fused to the glass. Then the pieces were fitted into H-shaped strips of lead, called cames, soldered at the joints, and the panels were set into an iron frame in the window.
Key idea
Why it works
Looking closely: The north rose at Chartres. A great wheel of glass about 10 meters across, set in stone tracery. From a small circle at the center, rings of shapes radiate outward like the petals of a flower: circles, then squares set on their corners, then half-circles at the rim. Each holds figures, too small to read from the floor but clear as color: deep blue grounds and red borders. Below stand five tall lancets with standing figures. The design is as strictly geometric as a snowflake.
Looking closely: The Sainte-Chapelle. King Louis IX of France built this chapel in his palace to hold relics he had bought, above all the Crown of Thorns. Its upper chapel is almost all window: fifteen tall windows of glass, separated only by thin stone piers, telling more than a thousand stories from the Bible. On a sunny day the walls dissolve into blue and red light. It was built very fast, between 1242 and 1248.
Worked example: Where is the color?
- The main colors are in the glass itself, made by adding metal oxides to the molten glass.
- Painters added only dark lines and shading with a glass-based paint, fired on.
- The lead cames outline the pieces.
Answer: The color is in the glass; painting added only lines and shading.
Common mistake