The Process of Making Stained Glass
A Thousand - Year Tradition of Light and Glass
Stained glass is one of the oldest surviving forms of decorative art — a craft dating back to the 7th century, refined during the Gothic period of the 12th and 13th centuries, and still practiced today in much the same way.
From the great rose windows of Chartres Cathedral to the domestic transoms of the 19th century, stained glass has served both sacred and secular purposes. Its enduring power lies in its union of color, light, and structure — designed to transform space and tell stories.
The making of stained glass remains largely a hand-crafted process, built on the same foundational steps practiced for over a millennium.
The Traditional Process of Stained Glass Making
1. Design & the Cartoon
Historically, artists created a cartoon — a full-scale drawing of the window’s design, used to guide all later steps. In medieval workshops, these designs were often inspired by religious iconography, geometric patterns, or floral motifs.
The cartoon is divided into individual shapes (or “pieces”), which will be cut from sheets of glass. A second layer of the cartoon, the cutline drawing, guides the actual cutting process.
2. Selection of Glass
Artisans select glass for its color, opacity, and how it interacts with light. Medieval glass was made by hand-blowing a molten blob into a cylinder, which was then flattened and cut. The resulting “antique” glass had rich irregularities and color gradients — highly valued today.
Modern art glass still mimics these properties. Types include:
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Cathedral glass: transparent, often richly colored
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Opalescent glass: used in the Tiffany tradition, with a marbled, opaque texture
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Flashed glass: clear glass coated with a thin layer of color, which can be selectively removed via etching or abrasion
3. Cutting the Glass
Using templates traced from the cartoon, the artisan cuts each piece by hand. Historically, glass was scored with a heated iron or diamond point; today, tungsten-carbide cutters are more common.
Each piece must fit precisely to form the final image. Tools like grozing pliers (used to nibble away small fragments) and running pliers (to snap a scored line) have been in use for centuries.
4. Leading or Foiling
Each piece of glass is fitted into lead cames — H-shaped channels made of soft lead. These are flexible enough to shape but strong enough to support the panel structurally. The method has remained virtually unchanged since the 12th century.
In the 19th century, the copper foil method was popularized by Louis Comfort Tiffany. Here, glass pieces are edged with adhesive copper tape and soldered together — allowing for finer detail and more intricate designs.
5. Soldering
Once assembled, the joints between pieces are soldered with a tin-lead alloy. This step permanently bonds the window into a rigid whole. Historically, this was done with hand-forged soldering irons heated over coals; today, electric irons are used.
6. Cementing and Waterproofing
In leaded panels, a waterproofing compound (traditionally linseed oil mixed with whiting) is brushed into the joints and allowed to cure. This cements the glass, strengthens the panel, and creates a weather-resistant seal.
7. Painting and Firing
Glass painting is one of the oldest decorative elements of the medium. Using vitreous paints made from powdered glass and iron oxide, artists add shading, texture, and narrative detail.
These paints are kiln-fired, permanently fusing them to the glass. In the Gothic era, this was the primary method of rendering faces, robes, and inscriptions on church windows.
Tools of the Trade
The stained glass artisan’s toolbox has changed little in 800 years. Many tools found in today’s studios — glass cutters, grozing pliers, lead knives, and soldering irons — mirror those seen in medieval manuscripts and workshops.
Kilns used for firing painted glass are more modern in construction but operate on the same principle: fusing pigment to glass through controlled heat.
Resources & Further Reading
The art of stained glass spans centuries and cultures, from medieval cathedral windows to contemporary architectural installations. Whether you're a curious collector, designer, student, or simply inspired by the craft, the resources below offer a deeper look into the history, techniques, and ongoing legacy of stained glass making around the world.
Explore further:
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Stained Glass Association of America
The national professional organization for stained glass artists, with resources on standards, history, and certified studios. -
The Corning Museum of Glass – History of Glass
A globally respected institution with archives, images, and scholarly writing on the evolution of glassmaking. -
Victoria and Albert Museum – Stained Glass Collection
A stunning digital collection of stained glass from medieval to modern, including windows, panels, and painted glass. -
The British Society of Master Glass Painters – Learning Resources
A UK-based guild offering technical guidance, historical articles, and design inspiration from master artists. -
The Metropolitan Museum of Art – Stained Glass Highlights
Browse stained glass pieces from their permanent collection, including Gothic, Renaissance, and Tiffany works. -
Getty Museum – Stained Glass: Puzzles of Color and Light
Craft That Connects Centuries
What makes stained glass unique among the decorative arts is its continuity. A piece made in the 14th century shares much in common — in tools, method, and intention — with one made today.
To understand how stained glass is made is to witness not just an art form, but a lineage. Each panel is a collaboration between artisan, glass, and light — shaped by hand, grounded in history, and designed to endure.