Stained Glass

Background

The technology for making glass dates back at least 5,000 years, and some form of stained glass was used in European Christian churches by the third or fourth century a.d. The art of stained glass flowered in the 12th century with the rise of the Gothic cathedral. Today only 10% of all stained glasses are used in churches and other religious buildings; the rest are used in residential and industrial architecture. Though stained glass has traditionally been used in windows, its use has expanded to lamp shades, Christmas ornaments, and even simple objects a hobbyist can make.

Stained glass has had various levels of popularity throughout history. The 12th and 13th centuries in Europe have been designated as the Golden Age of Stained Glass. However, during the Renaissance period, stained glass was replaced with painted glass, and by the 18th century it was rarely, if ever, used or made according to medieval methods. During the second half of the 19th century, European artists rediscovered how to design and work glass according to medieval principles, and large quantities of stained glass windows were made.

In America, the stained glass movement began with William Jay Bolton, who made his first window for a church in New York in 1843. But he was to be in the business for only six or seven years before returning to his native England. No other American practiced the art professionally until Louis Comfort Tiffany and John La Farge began working with stained glass near the end of the 19th century. In fact, the art of stained glass in the United States languished until the 1870s, and did not undergo a true revival until the turn of the century. At this time, American architects and glassmen journeyed to Europe to study medieval glass windows, returning to create similar art forms and new designs in their own studios.

A leaded stained glass window or other object is made of pieces of glass, held together by lead. The pieces of glass are about 1/8-inch (3.2 mm) thick and bound together by strips, called "cames" of grooved lead, soldered at the joints. The entire window is secured in the opening at regular intervals by metal saddle bars tied with wire and soldered to the leads and reinforced at greater intervals by tee-bars fitted into the masonry. A faceted glass panel differs slightly from traditional leaded stained glass in that it is made up of pieces of slab (dalle) glass approximately 8 inches square, or in large rectangular sizes, varying in thickness from 1-2 inches (2.5-5 cm). These slabs are not held together with lead; rather they are embedded in a matrix of concrete, epoxy, or plastic.

Raw Materials

Glass is made by fusing together some form of silica such as sand, an alkali such as potash or soda, and lime or lead oxide. The color is produced by adding a metallic oxide to the raw materials.

Copper oxide, under different conditions, produces ruby, blue, or green colors in glass. Cobalt is usually used to produce most shades of blues. Green shades can also be obtained from the addition of chromium and iron oxide. Golden glass is sometimes colored with uranium, cadmium sulfide, or titanium, and there are fine selenium yellows as well as vermilions. Ruby colored glass is made by adding gold.

The Manufacturing
Process

Stained glass is still made the same way it was back in the Middle Ages and comes in various forms. For the glass used in leaded glass windows, a lump of the molten glass is caught up at one end of a blow pipe, blown into a cylinder, cut, flattened and cooled. Artisans also vary this basic process in order to produce different effects. For example, "flashed glass" is made by dipping a ball of molten white glass into molten colored glass which, when blown and flattened, results in a less intense color because it will be white on one side and colored on the other.

So-called "Norman slabs" are made by blowing the molten glass into a mold in the shape of a four-sided bottle. The sides are cut apart and form slabs, thin at the edges and as much as 0.25 inch (0.6 cm) thik) at the center. Another form of glass, known as cathedral glass, is rolled into flat sheets. This results in a somewhat monotonous regularity of texture and thickness. Other similarly made glasses are referred to as marine antique, but have a more bubbly texture.

Processing the stained glass

• 1 Large manufacturers of stained glass mix the batch of raw materials, including alkaline fluxes and stabilizing agents, in huge mixers. The mix is then melted in a modern furnace at 2500°F (1371°C). Each ingredient must be carefully measured and weighed according to a calculated formula, in order to produce the appropriate color. For cathedral glass, the molten glass is ladled into a machine that rolls the glass into 1/8-inch (3.2 mm) thick sheets. The sheets are then cooled in a special furnace called an annealing lehr. The glass is then inspected, trimmed to standard size, and packed into cases.

  At a typical factory, eight to ten different color runs are made per day. Some manufacturers cut a small rectangle of glass from each run in order to provide a sample of each color to their customers. There are hundreds of colors, tints, and patterns available, as well as a number of different textures of cathedral glass. Different textures are produced by changing the roller to one having the desired texture. Glass manufacturers are continuously introducing new colors and types of glass to meet the demands of their customers.

Creating the window pattern

• 2 Though some of the tools to make stained glass windows have been improved, the windows are still hand crafted as they were centuries ago. The first step of the process involves the artist creating a small scale version of the final design. After the design has been approved, the craftsperson takes measurements or templates of the actual window openings to create a pattern. This pattern is usually drawn on paper or cardboard and is the actual size of the spaces to be filled with glass.

  Next a full-sized drawing called the cartoon is prepared in black and white. From the cartoon, the cutline and pattern drawings are made. The modern cutline drawing is a careful, exact tracing of the leadlines of the cartoon on heavy paper. The leadlines are the outlines of the shapes for patterns to which the glass is to be cut. This drawing serves as the guide for the subsequent placing and binding with lead of the many pieces of glass.

  The pattern-drawing is a carbon copy of the cutline drawing. It is cut along the black or lead lines with double-bladed scissors or a knife which, as it passes through the middle of the black lines, simultaneously cuts away a narrow strip of paper, thus allowing sufficient space between the segment of glass for the core of the grooved lead. This core is the supporting wall between the upper and lower flanges of the lead.

Cutting and painting

• 3 Colored glass is then selected from the supply on hand. The pattern is placed on a piece of the desired color, and with a diamond or steel wheel, the glass is cut to the shape of the pattern. After the glass has been cut, the main outlines of the cartoon are painted on each piece of glass with special paint, called "vitrifiable" paint. This becomes glassy when heated. The painter might apply further paint to the glass in order to control the light and bring all the colors into closer harmony. During this painting process, the glass is held up to the light to simulate the same conditions in which the window will be seen. The painted pieces are fired in the kiln at least once to fuse the paint and glass.

Glazing and leading

• 4 The next step is glazing. The cutline drawing is spread out on a table and narrow strips of wood called laths are nailed down along two edges of the drawing to form a right angle. Long strips of grooved lead are placed along the inside of the laths. The piece of glass belonging in the angle is fitted into the grooves. A strip of narrow lead is fitted around the exposed edge or edges and the next required segment slipped into the groove on the other side of the narrow lead. This is continued until each piece has been inserted into the leads in its proper place according to the outline drawing beneath.

Finishing

• 5 The many joints formed by the leading are then soldered on both sides and the entire window is waterproofed. After the completed window has been thoroughly inspected in the light, the sections are packed and shipped to their destination where they are installed and secured with reinforcing bars.

Faceted glass

• 6 For faceted glass windows, the process begins the same way, with the cutline and pattern drawings being made with carbons in a similar manner. The pattern drawing is then cut to the actual size of the piece of glass with ordinary scissors since there is no core of lead to allow for. The thick glass slabs next are cut with a sharp double-edged hammer to the shape of the pattern. To give the slab an interesting texture, the worker then chips round depressions in the glass with the same hammer. This is called faceting.

  Instead of glazing with lead, a matrix of concrete or epoxy is poured around the pieces of glass. The glass pieces have first been glued to the outline drawing, which is covered with a heavy coating of transparent grease so that the paper can be removed after the epoxy sets. The whole is enclosed within a wooden form, which is the exact size and shape of the section being made. The worker must wear gloves during this process, since epoxy resin is a toxic material. After hardening, the section is cleaned and cured prior to shipping and installation.

  The process for making an entire stained glass window can take anywhere from seven to ten weeks, since everything must be done by hand. Cost can vary widely depending on complexity and size, though some windows can be created for a cost as low as $500. The customer can choose an existing pattern rather than create an entirely new one to minimize costs. In this case, the pattern can be customized by altering shapes or by changing the placement of the central image.

The Future

In the last 20 years there has been an explosion in growth of glass studios in the United States and it appears this growth will continue. For instance, in Ohio alone the number of studios has increased from a mere half a dozen to at least 100. The Stained Glass Association of America membership includes 500 studio owners and 300 manufacturers. The circulation of its quarterly publication totals 6,000. There has been a resurgence in restoration overseas, and the home market continues to grow. The hobby market also appears strong, with one publication serving this market having a circulation of 15,000. It is clear that stained glass is now recognized as a true art form no matter where it is used, and innovative designs using this medium will continue to flourish.

Where To Learn More

Books

Clark, Willene B. The Stained Glass Art of William Jay Bolton. Syracuse University Press, 1992.

Clarke, Brian, ed. Architectural Stained Glass. McGraw-Hill, 1979.

Plowright, Terrance. Stained Glass Inspirations and Designs. Kangaroo Press, Australia, distributed by Seven Hills Book Distributors, 1993.

Other

Achilees, Rolf and Neal A. Vogel. Stained Glass in Houses of Worship. Inspired Partnerships Inc. and the National Trust for Historic Preservation, 1785 Massachusetts Avenue NW, Washington, DC 20036.

The Story of Stained Glass, 1984. The Stained Glass Association of America, PO Box 22642, Kansas City, MO 64113. 800-888-7422,816-333-6690.

—Laurel M. Sheppard

stained glass in general, windows made of colored glass. To a large extent, the name is a misnomer, for staining is only one of the methods of coloring employed, and the best medieval glass made little use of it.

Background

Colored glass as window decoration is of great antiquity in East Asia. Muslim designers fitted small pieces of it into intricate window traceries of stone, wood, or plaster, and this type of window mosaic is still in use. Colored glass was used in windows of Christian churches as early as the 5th cent., and pictorial glass as early as the 10th cent.

Medieval Stained Glass

With the development of medieval architecture, stained glass assumed a unique structural and symbolic importance. As the Romanesque massiveness of the wall was eliminated, the use of glass was expanded. It was integrated with the lofty vertical elements of Gothic architecture, thus providing greater illumination. Symbolically, it was regarded as a manifestation of divine light. In these transparent mosaics, biblical history and church dogmas were portrayed with great effectiveness. Resplendent in its material and spiritual richness, stained glass became one of the most beautiful forms of medieval artistic expression.

The early glaziers followed a sketched cartoon for their window design. They used a red-hot iron for cutting the glass to the required pieces, afterward firing in the kiln those that had received painted lines and shadings. The pieces were then fitted into the channeled lead strips, the leads soldered together at junction points, and the whole installed in a bracing framework of iron called the armature. The lead strips were adjusted to the articulation of the design and formed an integral part of it. The coloring of glass was achieved in the melting pot, where metallic oxides were fused with the glass. The metallic ores, although at first crude and limited, ultimately produced admirable color variations. The glass, available only in small pieces, gave thereby a jewellike quality to the colors. The pieces, by their uneven surfaces and varying thicknesses, gave the advantage of irregular and scintillating refractions of light.

Only fragments remain of glass from the 11th cent. The period of greatest achievement in the art extended from 1150 to 1250. Some examples from the 12th cent. can be seen in the windows of Saint-Denis (Paris), Chartres, and Le Mans in France, as well as at Canterbury and at York Minster in England. The windows of this period were characterized by rich dark colors, single figures, and scrollwork. A recurrent design, that of the Jesse tree, continued in use until the 16th cent.

By the beginning of the 13th cent. figures were abundantly used in scenes, being enclosed in geometrical medallions, such as circles, lozenges, or quatrefoils. A window was composed of many of these medallions. Color became more detailed and varied, and the prevailing scheme of red, blue, green, and purple, with small amounts of white, created tense and vibrant harmonies. In France the cathedral at Chartres is an unrivaled treasury of 13th-century glass; Sainte-Chapelle, Paris, is a triumph of architecture in which the walls present an illusion of being made entirely of fragile, exquisite stained glass. In England there are outstanding windows at York, Lincoln, and Salisbury. In the 14th cent. as medieval glass-making waned, medallion compositions were replaced by a single figure framed in canopied shrines. Many windows showed clear areas designed in grisaille .

See also rose window .

Later Stained Glass

In the 15th cent. glass artists achieved a silvery tone by the use of large proportions of white glass, and their figures of saints and apostles were surmounted by elaborate canopies. With improved glassmaking many of the assets of medieval stained glass (small, jewellike pieces of varying thicknesses) vanished. By the 16th cent. the material was smoother and in larger pieces; toward the middle of this century the use of enamel paints permitted the designs to be entirely painted on the glass and then fired. During the 16th cent. stained glass designers emulated the purely pictorial effects of Renaissance oil painting, with complicated perspectives, large scale, and realistic detail.

Stained Glass in the Modern World

Nineteenth-century romanticism and the Gothic revival brought fresh study and emulation of stained glass as well as of other medieval arts. The arts and crafts movement under William Morris was especially productive. A great contribution to American stained glass was made by John La Farge and Louis Comfort Tiffany . In modern art the medium has been used with great effectiveness by Rouault, Matisse, and Chagall.

Bibliography

See E. L. Armitage, Stained Glass: History, Technology and Practice (1959); J. Baker, English Stained Glass (1960); E. von Witzleben, Stained Glass in French Cathedrals (1968).

stained glass. Glass that has been given translucent colour in any of various ways, used particularly in church windows. Although the term ‘stained glass’ is now hallowed by long usage, much window glass could more strictly be described as ‘coloured’ (when it is dyed in its substance) or ‘painted’ (when pigments are applied to its surface). The art began in the service of the Christian Church and in its most characteristic development and its highest achievements it is essentially an art of Western Christendom, practised most splendidly in the west and north of Europe as an adjunct to Gothic architecture. Its early history is obscure, as there are few survivals before the Romanesque period (the church of St Paul at Jarrow, near Newcastle upon Tyne, has some fragments—placed in a window in 1980—that are probably more or less contemporary with the foundation of the monastery there in the late 7th century). The earliest known complete windows still in situ—in Augsburg Cathedral—are variously dated between 1050 and 1150, and show an art already nearly perfect, with a technique that has endured in principle to the present day, developed or modified only in inessential details.

Medieval windows are generally made up of hundreds of small pieces of glass of varied colours and shapes held together by strips of lead—somewhat like a jigsaw puzzle with dark outlines around the pieces. Windows of any size were made up of several panels so treated, and these were set in a framework of iron (‘armature’) that served not only as a support against wind pressure, but also to accentuate the main lines of the design of the window. The period from roughly 1150 to 1250 was the greatest age of stained glass: colours were strong and simple; designs were bold and fresh; and the feelings conveyed were lofty and awe-inspiring. The glass was coloured by adding various metallic oxides at the molten stage (copper for red, for example, and cobalt for blue). Such glass that is dyed one colour throughout its thickness is known as pot glass or pot metal. Details—such as facial features—were added to it by black pigment, which was fixed to the surface by means of a light firing. True ‘staining’ was introduced in the 14th century and was achieved by applying silver salts to white glass and firing it in a kiln; this produced a yellow colour, and orange could be obtained by repeating the process.

From the 15th century, stained glass generally became more pictorial, imitating the effects of oil painting, and this tendency was accentuated in the 16th century with the introduction of a range of enamel colours, with which the artist could paint on the glass more or less as he would on canvas (aided by the fact that improving technology enabled glass to be made in larger and flatter sheets than previously). This trend reached its height in the 18th century with such works as the west window of the chapel of New College, Oxford, designed by Reynolds and executed in 1778–85; it includes a Nativity scene inspired by Correggio, whose fluid, soft forms are a world away from the firm black outlines of medieval glass. Windows of this kind can have a charm of their own, but they are anathema to many students of the subject: E. Liddell Armitage, in his book Stained Glass (1959), describes the use of enamel as ‘an artistic poison…which killed practically every aesthetic faculty the craftsman of the period might inherently have possessed’. With the Gothic Revival in the 19th century there came a return to medieval principles, and William Morris and his associates (notably Burne-Jones) were among the foremost designers in this spirit. In the 20th century many noteworthy artists have designed stained-glass windows, in both figurative and abstract veins—among them Chagall, Matisse, Piper, and Patrick Reyntiens (1925– ), a leading specialist in the field who as well as creating his own glass has manufactured that designed by Piper.

The distinctive beauty of stained glass has been well described by Gerald Randall in Church Furnishing and Decoration in England and Wales (1980): ‘However intrinsically interesting wall and ceiling paintings may be, there is no doubt that the contribution of glass to our churches is more important. Glass has the advantage of transmuting light instead of merely reflecting it, and at its best has a sparkle and vitality that no opaque surface can match. Its effect changes with the light, from one day to another and from one hour to the next, and there are moments when the whole interior of a church seems to take fire from it.’

stained glass, initially a Christian art-form but subjected to changing attitudes and technical developments, is part of Britain's artistic heritage. Although the cathedral at York was glazed in the 7th cent., the use of pieces of coloured glass held together by lead strips (derived from mosaic and enamelling) did not appear in England until the 12th cent., notably at Canterbury. As Romanesque church architecture, where windows weakened structure, yielded to Gothic's soaring delicacy, partnership between mason and glazier enabled greater illumination, with supporting tracery part of the design. Medieval stained glass was essentially didactic, though the clergy were not unaware of the spiritual impact of luminescence and ever-changing light: the Scriptures were expounded, saints glorified, Jesse trees recollected Christ's ancestry, and great rose windows imagined the Apocalypse or the Last Judgement. Workshops were highly organized, while glaziers, artists in their own right and influenced by French and then Flemish models, kept stocks of cartoons (working drawings) which could be adapted for different glazing structures and then passed down from father to son. With important regional centres at Oxford, Coventry, and York, English glaziers were most prolific in the 14th cent., when glass-painting made extensive use of yellow stain and windows abounded with details of donors. The great east window at York (1405–8) typifies the high quality of the period, but purity of art-form began to decline as cathedral-building yielded to college chapels (King's, Cambridge) and parish churches (Fairford), and Renaissance influences encouraged naturalism and realism. The Reformation reacted iconoclastically to all religious imagery, with the loss of much stained glass, though heraldic windows for private houses and some churches were still produced. Destruction was most rampant during the Civil War, when cathedrals were sacked and men like Dowsing and Culmer gloried in their work. Simultaneous widespread warfare in Europe created a dearth of coloured glass, hence the virtual demise of the art. The Gothic Revival of the later 19th cent. led to renewed interest in both technique and history—Winston, Chance (who recreated ‘antique’ glass), Burne-Jones, Morris—before art nouveau designers such as Tiffany used it decoratively for lampshades and light fitments. The bulk of significant 20th-cent. work came after the Second World War, when the use of steel frames and reinforced concrete enabled huge walls of glass, experimentation in technique and colour, and a return to its incorporation as an integral element in architectural design.

A. S. Hargreaves

stained glass. Glass that has been given translucent colour in any of various ways, used particularly for creating pictorial designs in church windows. In its most characteristic development and its highest achievements it is essentially an art of Western Christendom, practised most splendidly in the west and north of Europe as an adjunct to Gothic architecture. Its early history is obscure, and the first surviving complete windows—in Augsburg Cathedral and datable c.1050–1150—show an art already nearly perfect in technique. Medieval windows are generally made up of hundreds of small pieces of glass of varied colours and shapes held together by strips of lead—somewhat like a jigsaw puzzle with dark outlines around the pieces. Windows of any size were made up of several panels so treated, and these were set in a framework of iron (‘armature’) that served not only as a support against wind pressure, but also to accentuate the main lines of the design of the window. The period from roughly 1150 to 1250 was the greatest age of stained glass: colours were strong and simple; designs were bold and fresh; and the feelings conveyed were lofty and awe-inspiring. From the 15th century, stained glass tended towards a greater pictorialism, imitating the effects of oil painting, and this trend reached its height in the 18th century, when some artists painted on glass more or less as they would on canvas. With the Gothic Revival in the 19th century there came a return to medieval principles, and William Morris and his associates (notably Burne-Jones) were among the foremost designers in this spirit. In the 20th century many noteworthy artists have designed stained-glass windows, in both figurative and abstract veins—among them Chagall, Matisse, and Piper.

stained glass Coloured glass used for decorative, often pictorial effect in windows. In its purest form, stained glass is made by adding metal-oxide colouring agents during the manufacture of glass. Shapes cut from the resulting sheets are then arranged to form patterns or images. These shapes are joined and supported by flexible strips of lead that form dark, emphatic contours. Details are painted onto the glass surfaces in liquid enamel and fused on by heat.

stained glass • n. colored glass used to form decorative or pictorial designs, notably for church windows, both by painting and esp. by setting contrasting pieces in a lead framework like a mosaic.