In the thirteenth century, glass-painting, already of considerable importance in the twelfth, attains even greater splendour in the windows that fill the space between the narrow framework of the walls like jeweled facades. The radiant shrine of glass, the dream of the medieval architect, has become a reality.
Stained glass windows are often viewed as translucent pictures. Gothic stained glass windows are a complex mosaic of bits of colored glass joined with lead into an intricate pattern illustrating biblical stories and saints lives. Viewed from the ground, they appear not as a picture but as a network of black lines and colored light. Medieval man experienced a window more than he read it. It made the church that special, sacred dwelling place of an all powerful God.
The development of stained glass design and production was not even throughout the Middle Ages. Constant war, famine, and plagues destroyed much of the original glass and often made such a large corporate endeavor unmanageable. The rise of new national identities also tended to create strong regional differences in aesthetics. One anecdote describes the accidental discovery of silver stain. When a silver button of one of the glaziers fell onto a piece of glass during the firing process it resulted in a rich gold stain on the fired piece. The eventual application of silver oxide to glass before firing, allowed the artist to obtain rich and varied hues of gold and yellow on clear glass, a prominent feature of most late medieval glass. This most probably is the technique, which gave stained glass its venerable name. Flashed glass was developed at this time, greatly increasing the artists pallet. Two layers of glass were fused together one on top of the other to produce different colors. Many refinements also occurred in the painters" techniques allowing for greater variations in shading. All of theses were to foreshadow the Renaissance, the development of realism, the painterly art, and the eventual diminution of the art of stained glass.
