The exact origin of stained glass is unknown. Its discovery was suggested by Pliny as an accident by Phoenician sailors. It is possible that it was a result of shipwrecked sailors building fires for their cooking pots on blocks of soda (natron) on top of beach sand. By morning, the melted sand and soda mixture would have produced hardened glass. It was more likely that potters, from Egypt or Mesopotamia, discovered the brittle treasure independently, when firing their wares. Anyone who has painted hand-molded clay in school art classes with a variety of coloured substances, knows that firing in the kiln will lead to hard-glassy coats. It is likely that the ancients tested many substances to discover which would generate the most durable and attractive coating for the otherwise dull and fragile pottery. Trial and error would have led to a glassy surface, which in turn would lead to the discovery of glass as an end unto itself.
Among the earliest manmade glass artifacts are Egyptian beads from about 2700 BC. The art proceeded to the first century AD, when Roman artisans were creating glass windows, though the product was irregular and not as transparent as we are accustomed to. The rise and importance of churches sped the craft into the glorious forms that we are familiar with. At St. Paul’s Monastery in Jarrow, England (founded in 686 A.D.), multiples pieces of coloured window glass were unearthed by archaeologists. Although there are examples of early stained glass windows, such as those from Augsburg Cathedral, the search continues for the earliest surviving examples.
Arabian filigree windows moved into Europe as the Moors entered Spain. Originally the glass, which appeared in the tenth century, were simply pieces inserted into marble or stone or glazed in plaster. To strengthen the bindings, iron ribs were added. As the coloured glass attracted builders, the fashion moved farther north, into latitudes that required more substantial settings to endure severe weather conditions.
Glass fragments, discovered from sites dated to 540 A.D. in Italy, include an image of Christ. Another small window, which included the popular Alpha and Omega symbols was unearthed in France and the site dated to 1000 A.D. The head of Christ became an increasingly popular image, a notable example found near Wissembourg, Alsace from 1068. As the earliest Christians, who had long been persecuted, began to feel safer, they moved from building secret spots of worship in their homes or beneath the earth, to building churches to house relics of the saints. The rulers of church and state sent emissaries to the Holy Land to bring back works of art, carved ivory, and jewels, including precious coloured glass. Christian art, borrowed and advanced the techniques as the need to enhance buildings of worship came into fashion.
The medieval Church became the most influential patron of the arts. As treasures from the Crusades flowed home to Europe, the need to display them in an environment of light, caused the French Abbot Suger of Saint Denis, to enlarge the windows and beautify them with stained glass. What started out as simple figures became complex and ornate with strong religious and personal symbolism, including heraldry.
It is the nature of glass that led to man’s enduring love affair. Glass is a solid that maintains qualities of a liquid. By capturing light, it appears to glow from within, transforming and passing light in the manner of a jewel. When created with the addition of metallic salts and oxides, the most brilliant and inspiring of colours can result, including the crimsons of gold, the deep royal blues of cobalt, the sun yellows of silver, and the forest greens of copper. These were displayed in the Gothic cathedrals of Europe, as craftsmen learned to generate results that could tolerate greater sizes and the ravages of inclement weather. In Medieval days, the craftsmen were interested in symbolic images more than realism. They employed grisaille, a brown enamel that covered the surface of the glass to define features rather than to transmit light. Later on, paler colours allowed for more light to pass, and the figures became larger, with more metallic oxides used to create coloured, painted masterpieces. The art form, throughout the ages generated results that increasingly exhibited the romance and spiritualism of the human spirit. It was stained glass that united architectural elements and with the mysteries of man’s beginning, journey, and attitudes to fellow men.