Stained Glass

I

Introduction

Stained Glass, translucent coloured glass used to compose designs in windows. The technique is similar to mosaic, the pieces of glass being held in strips of cast lead and mounted in a metal framework. Stained glass depends for its effect on light being transmitted through the translucent glass; thus the art is known as painting with light. It reached its zenith in Gothic architecture, most notably in France from about 1130 to 1330.

II

Materials and Techniques

Two types of glass were used in Gothic stained glass—pot glass and flashed glass. Pot glass was of uniform colour, which was achieved by adding oxides of iron (red), copper (green), or cobalt (blue) to the raw materials of glass, a transparent mixture of potash (later soda) and limestone. Flashed glass, made in order to obtain translucency with deep colours, was produced by fusing a thin layer of coloured glass to a thicker layer of clear glass while both were still hot.

The artist began by making a small-scale sketch of the design, and from this making a cartoon, a full-size plan drawn with lead or tin point on a wooden board or table coated with chalk or white paint; late Gothic and Renaissance cartoons were made on parchment, cloth, paper, or cardboard. The lines representing the lead supports were drawn in black. Next, sheets of coloured glass were laid on a table and cut with an iron tool heated to incandescence. The outlines of costume, facial features, and small designs were drawn on the individual pieces with a black or dark brown enamel-like paint made of powdered glass, metallic salts such as iron and copper oxides, other minerals, and liquid. These lines were usually drawn on the inner side of the glass and were fused to the stained glass by firing it at a low temperature. The malleable double lead strips, shaped like an H in cross section in order to grasp the edges of the glass on both sides, were then cut and shaped. Units of lead and glass were fixed to the window's larger iron frame, or armature, an integral part of the design in early windows.

III

Early History

The technique of colouring glass was known in Egypt and Mesopotamia in the 3rd millennium bc. A thousand years later, translucent coloured glass objects were moulded, and by the 1st century ad Roman glassmakers had mastered the art of blowing glass, which allowed vessels and thin transparent sheets to be made. Translucent and pierced screens of alabaster and glass were made in the Early Christian period (300-750), and coloured glass windows in wooden frames are mentioned in 6th- and 7th-century sources. From the 8th to the 12th century, walls in Islamic homes were sometimes pierced with stucco-framed glass windows.

The earliest European pictorial stained glass dates from the 9th century, though it is known only from written records. The earliest surviving fragments, depicting heads of Christ, from Lorsch Abbey in the Rhineland and Wissembourg, Alsace (now France); have been variously dated from the 9th to the 11th century.

IV

Romanesque Stained Glass

The art of stained glass flourished in the 12th century, with the flowering of Romanesque architecture and the building of great cathedrals in that style. The earliest extant Romanesque windows are five, over-life-sized standing Old Testament figures in the clerestory (upper storey) of Augsburg Cathedral, dated either 1050-1060 or 1100-1150. The centre for stained glass, however, became the Île de France, the region around Paris. The windows for the royal Abbey Church of Saint-Denis, commissioned by the famed Abbot Suger and made between 1144 and 1151 (now heavily restored), were soon followed by others at Chartres, Bourges, and Le Mans. Miraculously surviving the fire of 1194 are four resplendent windows, made between 1160 and 1170, in Chartres Cathedral. Three of them, lancet windows, remain in the west façade; the fourth, the noble Notre Dame de la Belle Verrière, was placed in the 13th-century structure's ambulatory.

French Romanesque stained glass influenced that of Germany and England. The most popular subjects were single standing figures set in niches, or two figures—one above the other—in the clerestory, and the Tree of Jesse, depicting the ancestors of Christ, in tall lancet windows. These themes continued to be used in the 13th century at Strasbourg, Le Mans, Troyes, Soissons, and the Sainte Chapelle in Paris. Scenes from the Passion were also popular; at Poitiers Cathedral the Crucifixion is the subject of its main window. The predominant colours used at this time were blue (especially for the background), red, yellow, and green. Violet, brown, and white with a green or blue cast were secondary, and pinkish shades served as flesh tones. Twelfth-century windows, in their refinement and delicacy, resembled the art of the goldsmith and enamel worker.