Stained glass possesses an aura of mystery and romance. It is the interplay between light and color that sparks the imagination. Today, stained glass is a common architectural feature found in various types of buildings.
The north rose window of the Chartres Cathedral (Chartres, France), donated by Blanche of Castile.
The Discovery of Glass
Many histories of stained glass begin with Pliny’s tale of the accidental discovery of glass by Phoenician sailors. The legend recounts shipwrecked sailors who set their cooking pots on blocks of natron (soda) from their cargo then built a fire under it on the beach. In the morning, the fire’s heat had melted the sand and soda mixture and the resultant mass had cooled and hardened into glass.
Today, though, it is thought that Pliny - though energetic in collecting material - was not very scientifically reliable. It is more likely that Egyptian or Mesopotamian potters accidentally discovered glass when firing their vessels.
Early Examples in Egypt
The earliest known manmade glass is in the form of Egyptian beads from between 2750 and 2625 BC. Artisans made these beads by winding a thin string of molten glass around a removable clay core.
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Egyptian Faience Beads.
Now, researchers from London and Germany have found evidence that the Egyptians were making their own glass as far back as 3,250 years ago. The new evidence, uncovered in an Egyptian village named Qantir, shows that an ancient glassmaking factory had operated there. Chemical studies of the remains suggest how the Egyptians made their glass.
First, the ancient glassmakers crushed quartz pebbles together with the ashes of burnt plants. Next, they heated this mixture at low temperatures in small clay jars to turn it into a glassy blob. In the second part of the process, the glassworkers poured this refined powder through clay funnels into ceramic containers and heated the powder to high temperatures.
Egyptian glassmakers probably sold and shipped their glass to workshops throughout the Mediterranean. At the time, wealthy people exchanged sculpted glass pieces as a way to make political bonds with each other.
The Evolution of Stained Glass
Stained glass found its beginnings as an art form in Ancient Egypt. Egyptians found that when they wound melted glass around a piece of clay, they could create glass with a hollow center that could be used for pottery or jewelry. Later on, the Romans began to include glass in buildings to create windows with glass panes. Many of these early works were lacking in uniformity or had noticeable imperfections. However, though those these early works are far from perfect, they gave rise to a whole new art form and therefore are considered to be extremely precious and valuable.
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In the first century AD, the Romans glazed glass into windows. They cast glass slabs and employed blowing techniques to spin discs and made cylinder glass.
One of the oldest known examples of multiple pieces of colored glass used in a window were unearthed at St. The oldest complete European windows found in situ are thought to be five relatively sophisticated figures in Augsburg Cathedral. These five windows show fired glass painting which utilizes line and tonal shading and they are made of bright, varied colors of glass.
In 1930 at Saint Vitale in Ravenna, Italy, the archaeologist Cecchelli dug up three glass fragments showing Christ with a cruciform nimbus standing between an alpha and omega painted with grisaille.
Medieval Stained Glass
The medieval Church was the most important patron of the arts. Abbot Suger of Saint Denis reformed and rebuilt the abbey and augmented its wealth. As its treasures increased, many pilgrims told stories of it and its influence spread. Window subject treatment grew during the Gothic period, expanding from simple figures to a complex iconography fully understood by only a few experts today.
This iconography made use of symbolism based on bestiaries which can be called “unnatural history” and on complicated typology (Old Testament stories that symbolize New Testament events). Today, scholars study these windows to learn about the daily life of the time. Guilds of workmen donated windows that included likenesses of themselves engaged in their businesses.
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The relationship between Saint Denis and Chartres is well established through a similarity of style and iconography. Stained glass historians today re-trace the work of traveling studios.
Although the cathedral is a contemporary of Chartres, the windows of Bourges are more archaic. The Gothic style was also developing outside France. The stained glass in the cathedral of Lausanne, Switzerland shows a marked French influence.
The History of Stained Glass
Renaissance Stained Glass
Renaissance stained glass is very different from that of the previous period. The themes are still principally biblical. Because subjects in renaissance stained glass are shown dressed in period clothing, a knowledge of the history of costume helps date windows. Allegorical themes are even more elaborate than medieval iconography. Figures represent abstract ideas.
Stained glass was used in secular buildings during the renaissance period. Historic scenes or heraldry were placed in town halls and small panels (usually silver stain and paint on white glass) were incorporated into clear glass windows in homes. The labors of the seasons are a favorite theme during this period.
In large church windows, the scenes extended over the whole, ignoring the mullions. Buildings portrayed in the windows are solid, in classical style, shown with correct perspective. Some action takes place far back from the picture plane with vistas in the distance.
The way stained glass craftsmen worked also changed. Artists drew cartoons on paper and were able to carry those cartoons to different clients. Sample books of patterns were also transported. Workshops stayed in one place through several generations, often attached to a cathedral that constituted their major employer. Finished windows were shipped to secondary customers at a distance.
Silver stain, flashed glass (abraded rather than acid etched,) and colored enamels were widely used. The diamond cutter was used, making possible larger, more complicated pieces of glass. Leads became thinner and less important to the design.
Although Gothic stained glass came late to Italy, the Renaissance style flourished early. Flemish stained glass designs in the Renaissance are akin to the oil paintings of the Van Eycks; that is, they often show energetic forms and contrasting colors. A characteristic crisp fold in garments is evident in this period.
Decline and Revival
Experts agree that stained glass reached a low ebb sometime between the late medieval age and the nineteenth century. The reasons were religious, political and aesthetic. The Church had been the principal patron of the arts. The new Protestants were hostile to elaborate art and decoration. Even in the Roman Catholic countries, the Counter-Reformation called for simpler religious buildings.
After the discovery of King Tutankhamun's tomb in 1922, ancient Egyptian motifs were once again revived - pervading even American residential architecture.
Types of Stained Glass Today
Stained glass comes in three basic forms today: leaded, art, and faceted.
- Leaded: This is what we normally refer to as stained glass even though the term “stained glass” means any colored glass. It is usually one-eighth inch thick and is held together by lead “cames.”
- Art-Glass: This form was made popular by Louis C. Tiffany using colored enamels and opalescent glass. The enamels actually change the color of the light but are applied only to the surface of the glass and are fired on as enamels on copper.
- Faceted: Faceted windows are made from slabs of glass ranging anywhere from one-half inch to three or four inches in thickness.
Stained Glass Techniques
The primary method of including colour in stained glass is to use glass, originally colourless, that has been given colouring by mixing with metal oxides in its melted state (in a crucible or "pot"), producing glass sheets that are coloured all the way through; these are known as "pot metal" glass. A second method, sometimes used in some areas of windows, is flashed glass, a thin coating of coloured glass fused to colourless glass (or coloured glass, to produce a different colour).
Another group of techniques give additional colouring, including lines and shading, by treating the surfaces of the coloured sheets, and often fixing these effects by a light firing in a furnace or kiln. These methods may be used over broad areas, especially with silver stain, which gave better yellows than other methods in the Middle Ages. Alternatively they may be used for painting linear effects, or polychrome areas of detail.
The most common method of adding the black linear painting necessary to define stained glass images is the use of what is variously called "glass paint", "vitreous paint", or "grisaille paint". This was applied as a mixture of powdered glass, iron or rust filings to give a black colour, clay, and oil, vinegar or water for a brushable texture, with a binder such as gum arabic.
"Silver stain", introduced soon after 1300, produced a wide range of yellow to orange colours; this is the "stain" in the term "stained glass". Silver compounds (notably silver nitrate) are mixed with binding substances, applied to the surface of glass, and then fired in a furnace or kiln. They can produce a range of colours from orange-red to yellow. Used on blue glass they produce greens.
Colored Glass Additives
Glass is colored by adding metallic oxide powders or finely divided metals while it is in a molten state.
| Additive | Color |
|---|---|
| Copper oxides | Green or bluish green |
| Cobalt | Deep blue |
| Gold | Wine red and violet |
| Iron(II) oxide | Bluish-green |
| Metallic gold (low concentrations) | Rich ruby-colored glass |
| Selenium | Pink and red |
| Sulphur, carbon and iron salts | Amber (yellowish to almost black) |
| Titanium | Yellowish-brown |
| Cadmium with sulphur | Deep yellow |
| Uranium (0.1% to 2%) | Fluorescent yellow or green |
| Manganese | Amethyst |
| Tin dioxide with antimony and arsenic oxides | Opaque white |
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