Stained Glass: What It Is, How It’s Made, and Why It Matters
What stained glass actually means
Stained glass usually means colored glass, either as a raw material or as the finished artwork made from it. It’s most known for flat panels used in windows, especially in churches or old buildings. But today, stained glass artists also build 3D pieces and sculptures out of it. People now often use the term to describe all sorts of decorative glasswork. That includes things like home leadlight panels or Tiffany-style lamps.
Stained glass gets its color from metallic salts added when the glass is first made. After that, artists might decorate it more. They often cut the glass into small shapes and fit them together into a larger design. The pieces are joined with thin lead strips called cames. These sit in a firm frame that holds everything in place. Artists sometimes paint details on the glass and use a special yellow stain made from silver to bring out more depth or contrast. The term stained glass can also cover enamelled glass, where the color is painted on the surface and then melted into the glass using a kiln.
How stained glass works as a craft
Making stained glass is both art and engineering. First, the artist has to design something that looks good and actually works in the space it’s made for. Then they have to build it so it lasts. A stained glass window needs to fit the opening just right. It also has to handle wind and rain. If the window is big, it has to support its own weight too.
A lot of stained glass windows from the late Middle Ages are still around today. That says a lot about the skill that went into making them. In Western Europe, stained glass windows, along with illuminated manuscripts, are one of the few medieval art forms that survived mostly intact. The point of a stained glass window wasn’t really to let people look outside or even let in light. It was more about shaping how the light entered. That’s why some people call them “lit-up wall art.” They’re meant to change the way light feels inside a space.
What stained glass designs usually show
The design in a stained glass piece can be abstract or it can show people, scenes, or symbols. Sometimes it tells a story. The stories might come from the Bible, from history, or from literature. You’ll also see saints, coats of arms, and other symbols. The theme usually fits the building. In churches, you might see scenes from the life of Jesus. In a government building, you could find shields for each region. In a college hall, there might be figures for different fields like art or science. And in a house, it might just be flowers, animals, or a landscape.
How stained glass is made
Back in the late Middle Ages, glassmakers set up workshops near places with easy access to silica. That’s the key material for making glass. But silica melts at really high temperatures, which not every workshop could pull off. To lower the heat needed, they mixed in things like potash, soda, or lead. They also added lime to make the glass more stable and harder.
To color the glass, they mixed in metal oxides or metal powder while the glass was still molten. Different metals make different colors. Copper gives you green or bluish green. Cobalt turns it deep blue. Gold makes a rich red or violet. These days, red glass is often made with copper instead of gold. Copper is cheaper and makes a brighter, more orange-red color.
If the color gets mixed into the glass while it’s still cooking in the furnace pot, the result is called pot metal glass. That’s different from flashed glass, which is made by layering clear glass over colored glass or vice versa.
History of Stained Glass: Where It Started and How It Evolved
Origins of Colored Glass
Colored glass has been around since ancient times. The Egyptians and Romans were both skilled at making small colored glass items. Phoenicia was also a big player in glassmaking, especially in cities like Sidon, Tyre, and Antioch. Two well-known Roman glass pieces are in the British Museum. One is the Lycurgus Cup, which looks like a dull yellow but glows red-purple when light passes through it. The other is the Portland Vase, a dark blue piece with white carved detail layered over it.
In the 4th and 5th centuries, early Christian churches used thin slices of alabaster in wood frames for their windows. These gave off a stained-glass-like effect, even though they weren’t technically stained glass.
There’s early proof of real stained-glass windows in Britain as far back as the 7th century. One of the oldest known mentions comes from 675 AD. That’s when Benedict Biscop brought over craftsmen from France to glaze the windows of St Peter’s Monastery in Monkwearmouth. Archaeologists have found hundreds of colored glass fragments and lead strips from that period at Monkwearmouth and Jarrow.
Glassmaking in the Middle East and the Islamic World
Glass production in Syria carried on into the Islamic era, with Raqqa, Aleppo, and Damascus leading the way. The focus there was more on crystal-clear or gilded glass than on colored pieces.
Stained glass in Southwest Asia dates back even further. One of the oldest glassmaking recipes comes from ancient Nineveh, in the 7th century BC. Later, in the 8th century, the alchemist Jābir ibn Hayyān wrote Kitab al-Durra al-Maknuna, which detailed how to make colored glass and fake gemstones. He described glassmaking practices from ancient Babylon and Egypt. These methods were used to decorate mosques, palaces, and other public buildings across the Islamic world. Islamic stained glass often avoids images of people or animals. Instead, it focuses on geometric patterns, floral designs, and calligraphy.
In Persia, now Iran, stained glass flourished during the Safavid period from 1501 to 1736 and continued into the Zand dynasty through the late 1700s. In Persian architecture, stained-glass windows are called Orosi, sometimes spelled Orsi or Arasi. These windows were designed not just for decoration but also to filter harsh sunlight in hot climates.
The Middle Ages: The Peak of Stained Glass Art
Stained glass reached its high point as an art form in the Middle Ages. At that time, most people couldn’t read, so stained glass windows became a way to tell Bible stories using pictures. The windows were pretty. And they helped teach people who couldn’t understand written scripture.
Between about 950 and 1240, during the Romanesque and Early Gothic periods, windows didn’t yet have tracery. That meant they needed strong iron frames to hold the glass in place. You can still see these early examples at places like Chartres Cathedral in France and the east end of Canterbury Cathedral in England.
As Gothic architecture advanced and became more detailed, the windows got bigger and let in more light. But as they grew, they had to be split into smaller parts using vertical supports and stone patterns called tracery. This change led to even more intricate designs, especially during the Flamboyant style in Europe. In England, this same trend showed up in what’s known as the Perpendicular style. In France, it appeared in the Rayonnant style. Either way, the windows just kept getting bigger and more complex.
Gothic cathedrals and the rise of complex designs
When stained glass was used in tall Gothic cathedrals and churches, the art evolved fast. The designs got bolder. Circular windows, known as rose windows, started in France. They began as simple holes cut into thin stone. Later, they turned into wheel-like shapes, like the one on the west front of Chartres Cathedral. Over time, the patterns became far more complex. The builders used hundreds of design points to draft the tracery. You can see this at Sainte-Chapelle in Paris and in the "Bishop's Eye" window at Lincoln Cathedral.
Chartres became the top center for stained glass production. The glass made there stood out for its quality and detail.
Renaissance stained glass in Florence
One of the first big stained-glass projects during the Renaissance was in Florence Cathedral. Lorenzo Ghiberti came up with the plan. It included three round windows for the dome and three for the front of the building. These were designed between 1405 and 1445 by some of the best artists of the time. Ghiberti himself worked on it, along with Donatello, Uccello, and Andrea del Castagno. The larger round windows each showed one scene from the life of Christ or the Virgin Mary, framed by wide floral borders. Two smaller windows on the front, also by Ghiberti, showed the martyrs Saint Stephen and Saint Lawrence. One of the dome windows is now missing. The one by Donatello has lost most of its painted detail.
Later styles and movements across Europe
Stained glass kept going in Europe, even as styles changed from Gothic to Classical. Germany, Belgium, and the Netherlands all have examples of this change, even though Protestantism was spreading. In France, a lot of stained glass came from the Limoges workshops. In Italy, Murano became known for combining stained glass with lead crystal in the same piece.
The French Revolution led to the damage or destruction of many windows across France. Still, the country holds more Renaissance stained glass than anywhere else. This is especially true in Normandy and Champagne, where glass workshops thrived in several cities up to the early 1600s. Linard Gonthier, a well-known stained glass painter, worked in Troyes until 1642. Just in the Aube region, there are over a thousand 16th-century windows still standing today.
Destruction and loss in England
During the Reformation in England, thousands of stained glass windows from medieval and Renaissance times were destroyed. Many were replaced with plain, clear glass. This happened under Henry VIII, during the Dissolution of the Monasteries. Thomas Cromwell also issued orders to remove what he called "abused images", meaning anything used for religious devotion. Almost all the stained glass from that time was either smashed or lost. Only a few pieces survived intact. Some of the best examples left are in the private chapel at Hengrave Hall in Suffolk.
This period of destruction wiped out the knowledge of how to make stained glass in the old way. The craft wasn't brought back in England until the early 1800s.
Surviving Works in the Netherlands
In the Netherlands, there’s a rare set of stained glass windows still intact at the Grote Sint-Jan Church in Gouda. Some of these windows reach up to 18 meters high, which is about 59 feet. They date from 1555 through the early 1600s. The earliest ones were made by Dirck Crabeth and his brother Wouter. Many of their original design drawings, or cartoons, have also survived, which is rare.
Stained Glass in Latin America
Stained glass first showed up in Latin America in the 1600s and 1700s. Portuguese and Spanish settlers brought it over. But it wasn’t until the 1900s that things really took off. European artists started setting up their own workshops across Latin America. This change brought new techniques and a move away from traditional styles. You can see examples of this in Chile, at the Basílica Nuestra Señora de Lourdes and the Templo Vótivo de Maipú. These pieces show how artists began creating more original, modern work.
The Gothic Revival in England
In England, stained glass came back into focus during the early 1800s thanks to the Catholic revival. This movement brought renewed interest in medieval church design. Gothic architecture made a comeback, especially under thinkers like John Ruskin, who called it “the true Catholic style.” Architect Augustus Welby Pugin helped lead the charge. As new churches popped up in growing cities and older ones were restored, demand for stained glass surged.
Some of the earliest stained glass makers in 19th-century England included William Warrington and John Hardman from Birmingham. Hardman’s nephew, John Hardman Powell, pushed the craft further and even showed work at the 1876 Philadelphia Exhibition, which had a big influence on stained glass in the United States. Other English makers at the time were William Wailes, Ward and Hughes, Clayton and Bell, Heaton, Butler and Bayne, and Charles Eamer Kempe. In Scotland, Daniel Cottier started designing stained glass and even opened workshops in Australia and the U.S.
Stained Glass Revival in France
France kept a more steady stained glass tradition than England during this time. In the early 1800s, French stained glass makers were using big panes of glass that they painted and then fired. These designs were often copied from oil paintings by well-known artists. In 1824, the Sèvres porcelain factory began making stained glass to meet growing demand. After the French Revolution, many churches had been damaged or stripped of art. During the 19th century, architect Viollet-le-Duc led large-scale restorations of these buildings. Many ancient stained glass windows in France were repaired or remade during this time.
From 1839 onward, artists began creating glass that closely copied medieval styles, both in design and in the type of glass used. Henri Gèrente and André Lusson were leading figures in this movement. Some French glassmakers leaned more toward a Classical look. These windows often stood out with a bright cerulean blue in the backgrounds instead of the deeper blue seen in Chartres glass. They also made use of pinks and mauves that weren’t common in older work.
Stained Glass Revival in Germany and Beyond
In Germany, many older buildings were restored in the mid to late 1800s. Some, like Cologne Cathedral, were even completed for the first time, but in a medieval style. With that came a strong need for stained glass. A lot of the designs from this period were based directly on engravings by artists like Albrecht Dürer. Even original designs often copied that same look. Unlike older glass that used lead lines for detail, much of the German glass from this time had large painted sections.
Ludwig I of Bavaria started the Royal Bavarian Glass Painting Studio in 1827. One major company that came later was Mayer of Munich, which began making glass in 1860 and is still in business today as Franz Mayer of Munich, Inc. Their work didn’t stay local. They sold stained glass all over Europe, as well as in the U.S. and Australia. Studios also started popping up in Italy and Belgium during this same stretch of time.
Stained Glass in the 19th and Early 20th Century: Key Artists and Movements
Austria-Hungary: Carl Geyling and His Legacy
In the Austrian Empire and later in Austria-Hungary, Carl Geyling stood out as one of the most important stained glass artists of his time. He opened his own studio in 1841. After him, his son took over and kept the business running under the name Carl Geyling’s Erben, which still operates today. The studio completed a wide range of stained glass windows for major churches across Vienna and other cities. Their work was so well regarded that they earned an imperial and royal warrant of appointment from Emperor Franz Joseph I of Austria.
England’s Arts and Crafts Revival
In England, some of the most original stained glass work came from the Pre-Raphaelites, especially William Morris and Edward Burne-Jones. Both were major figures in the Arts and Crafts Movement, which gave stained glass a serious comeback in the English-speaking world.
One of the most important names in that movement was Christopher Whall. He lived from 1849 to 1924 and was known for insisting that designers should be hands-on in building the windows themselves. He even wrote a well-known guide called Stained Glass Work, published in 1905 in both London and New York. His best-known work is the set of windows he made between 1898 and 1910 for the Lady Chapel at Gloucester Cathedral.
Whall also taught at the Royal College of Art and the Central School of Arts and Crafts in London. Many stained glass artists came out of his classrooms, including Karl Parsons, Mary Lowndes, Henry Payne, Caroline Townshend, Veronica Whall (his daughter), and Paul Woodroffe.
His work also had a big impact on Douglas Strachan, a Scottish artist who took the Arts and Crafts style and gave it an expressive edge. His designs were bold and symbolic but always precise. In Ireland, Whall’s student Alfred Child taught at Dublin’s Metropolitan School of Art, and his students helped build a whole new national stained glass style. Artists like Wilhelmina Geddes, Michael Healy, and Harry Clarke became leading figures in that Irish movement.
Art Nouveau and Belle Époque in Glass
In France and Eastern Europe, stained glass followed the Art Nouveau or Belle Époque style. You can spot this style by the flowing lines in the leadwork and the soft, swirling designs. In France, Francis Chigot in Limoges was a major name in this style. In Britain, the same type of refined, formal design showed up in the leadlight work of Charles Rennie Mackintosh.
Early American Studios and Innovations
In the United States, the first major stained glass studio was J&R Lamb Studios. They started in New York City in 1857 and were a leading source for church stained glass for years.
Two of the biggest names in American stained glass were John La Farge and Louis Comfort Tiffany. La Farge invented opalescent glass and got a U.S. patent for it on February 24, 1880. Tiffany, who worked on similar methods, got his own patents that same year in November. Tiffany also helped develop a different way to put the glass pieces together using copper foil instead of lead. That method became one of his trademarks, especially in his famous lamps. Sanford Bray from Boston actually patented the copper foil technique in 1886.
But not everyone liked the look or the technique of opalescent glass. Architects like Ralph Adams Cram pushed back against it. They helped bring traditional stained glass back into focus in the early 1900s.
One of the most influential names in that return to tradition was Charles J. Connick. He opened his Boston studio in 1913. His work was heavily inspired by medieval stained glass he studied in Europe and by the teachings of Christopher Whall. Connick went on to design hundreds of windows across the U.S., including major works at Princeton University Chapel (1927 to 1929) and Heinz Memorial Chapel in Pittsburgh (1937 to 1938).
Other American artists who leaned into medieval-style stained glass included Nicola D’Ascenzo in Philadelphia, Wilbur Burnham in Boston, and Reynolds, Francis & Rohnstock. In New York, Henry Wynd Young and J. Gordon Guthrie were also key figures.
Studios and Artist Collectives in the 20th Century
Many stained glass firms that thrived in the 19th century shut down in the early 20th. Gothic revival faded and gave way to new styles. But some artists started sharing studio spaces and building creative communities.
One of these places was the Glass House in London, run by Mary Lowndes and Alfred J. Drury. Another was An Túr Gloine in Dublin, managed by Sarah Purser. That group included artists like Harry Clarke, who helped shape the look of modern Irish stained glass.
Stained Glass Revival After World War II
In the mid-20th century, stained glass made a comeback. The push came from the need to replace thousands of church windows across Europe that had been blown out during World War II. German artists led this wave of restoration. A lot of the stained glass made during that time was plain and dull. Many designs weren’t even made by hand but mass-produced in factories.
Some artists didn’t just want to restore the old. They wanted to take the tradition and make it modern. They tried new things with glass while keeping some of the older techniques. One of the big innovations from that time was the use of thick slab glass. This style is called dalle de verre. The glass is set into concrete or epoxy resin instead of lead. Jean Gaudin came up with the idea, and Pierre Fourmaintraux brought it over to the UK. One of the best-known artists to use this method was Dom Charles Norris, a Benedictine monk from Buckfast Abbey. He made a lot of work using this heavy, bold technique.
Another new method was called gemmail. French artist Jean Crotti started it in 1936 and refined it through the 1950s. This technique overlaps pieces of glass instead of joining them with lead. That creates more subtle color changes and more freedom in blending. Some famous paintings from the late 1800s and early 1900s, including works by Picasso, were recreated using gemmail. A major artist who worked with this method was German painter Walter Womacka.
Modern Artists Who Changed the Medium
In the early 20th century, some artists began to see stained glass as a serious medium for abstract art. Theo van Doesburg and Piet Mondrian were among the first to try this. Then, in the 1960s and 70s, Expressionist painter Marc Chagall created stained glass windows full of rich color and loaded with symbolism.
Several artists became well known for pushing stained glass forward during the 20th century. That includes John Hayward, Douglas Strachan, Ervin Bossanyi, Louis Davis, Wilhelmina Geddes, Karl Parsons, John Piper, and Patrick Reyntiens. Others include Johannes Schreiter, Brian Clarke, Paul Woodroffe, and Jean René Bazaine, who worked at Saint Séverin. Sergio de Castro created work at Couvrechef-La Folie in Caen, in Hamburg-Dulsberg, and in Romont, Switzerland. The Loire Studio, led by Gabriel Loire in Chartres, was also key. One major example from England is the west windows of Manchester Cathedral, designed by Tony Hollaway. These windows are known for their symbolic depth and detail.
Germany’s Role in Modern Stained Glass
Germany didn’t stop at war recovery. Artists kept evolving stained glass into something new. During the years between the wars, Johan Thorn Prikker and Josef Albers explored the medium in bold ways. After the war, others followed, including Georg Meistermann, Joachim Klos, Johannes Schreiter, and Ludwig Schaffrath.
This group of German artists broke away from figures and storytelling. Instead, they went for abstract shapes, strong geometry, and expressive line work. They stopped painting on the glass and started using color and structure to carry the design. They used lead strips for form, not function. Some critics say this marked the first real stained glass movement since the Middle Ages.
Ludwig Schaffrath’s work is a clear example of this change. He filled entire walls with colored and textured glass, using it as a full architectural element. In the 1970s, this approach caught the eye of young British artists. Brian Clarke, for example, was heavily inspired by the bold scale and abstraction coming out of Germany.
Stained Glass in the UK: A Longstanding Craft and Community
In the United Kingdom, the main professional group for stained glass artists is the British Society of Master Glass Painters. It’s been around since 1921. They’ve been publishing The Journal of Stained Glass every year since 1924. It's still the only group in the country that focuses fully on stained glass as both an art and a craft.
From the beginning, their mission has stayed pretty steady. They push for high standards in both painting and staining techniques. They also serve as a hub for artists to trade ideas, share new techniques, and support each other’s work. A big part of what they do is help protect Britain’s stained glass history, which is huge.
Their website, www.bsmgp.org.uk, lists talks, workshops, and tours all about stained glass. You’ll also find portfolios of recent work by members, details on training programs, and guidance on how to care for old windows. They’ve got a searchable index of The Journal of Stained Glass, which is a solid resource if you’re doing any research on the topic.
After World War I, a lot of families in the UK started putting up stained-glass window memorials for loved ones who had died. Most of these came from wealthier families, and you can still find them in churches all over the country.
Stained Glass in the United States: Tradition and Innovation
In the US, stained glass also has a strong foothold. There's a trade group called the Stained Glass Association of America. It’s been around for over a hundred years. Their goal is to keep the craft alive. They offer training, write up standards, and give working artists the tools to build their skills.
They also take a stand when it comes to defending stained glass as an art form, especially when rules or regulations threaten to box it in. Kathy Bernard is the group’s current president.
Some universities in the US teach the old-school methods. One example is Florida State University’s Master Craftsman Program. They recently finished a 30-foot stained-glass window that looks out over Bobby Bowden Field at Doak Campbell Stadium. Robert Bischoff, the program’s director, designed the piece along with his wife Jo Ann.
There’s also a massive stained-glass project at Utah Valley University in Orem, Utah. It’s called Roots of Knowledge and stretches 200 feet. People have compared it to the windows in big European cathedrals like Cologne Cathedral in Germany, Sainte-Chapelle in France, and York Minster in England.
Plenty of stained glass artists in the US today are also doing new things with the medium. Instead of making pictures or scenes, some are building their windows around grid patterns and abstract forms.
Other Types of Stained Glass
Cylinder or Mouth-Blown Glass (Also Called Muff Glass)
To make cylinder glass, a glassmaker uses a blowpipe to gather a ball of molten glass straight from the furnace. That hot glob is shaped by hand, then air is blown into it to form a bubble. They use metal tools, soaked wooden molds, and gravity to stretch and form the glass into a long, tube-like cylinder. It doesn’t happen all at once. The glass is reheated during the process so it stays workable.
Once the shape is close to what they need, they remove the bottom of the cylinder. Then they let it cool down. After that, one side of the cylinder is sliced open. The whole piece is put back into a hot oven where it quickly heats up again and flattens into a sheet. From there, it’s moved to an annealer. That’s a special oven where the glass cools slowly and evenly. This final step keeps the glass stable and strong.
This kind of glass, called hand-blown or mouth-blown cylinder glass, is also known as muff glass. It was one of the main types used in making traditional stained glass windows, along with crown glass.
Crown Glass
Crown glass is also made by hand. It starts the same way, by blowing air into a ball of molten glass to make a bubble. But instead of forming a cylinder, the glassmaker spins the bubble. They either do this by hand or use a spinning table, kind of like a fast potter’s wheel. The spinning flattens the glass into a wide, thin disk.
That sheet of glass can then be trimmed down into smaller panes. It might be clear, or it could be colored if it’s going to be used for stained-glass windows. The spinning process creates soft, curved wave patterns across the glass. These ripples are a telltale sign of crown glass.
The center of the disk, called the bull’s-eye, stays thicker because it doesn't spin out as much. That part also holds the pontil mark. It’s a small lump left by the rod that supported the glass while it was spinning. Because of that thicker middle and the irregular surface, the bull’s-eye section isn’t as clear. But it’s still been used in windows for homes and churches.
Crown glass is still made today, though it’s not mass produced like other types.
Rolled Glass
Rolled glass, sometimes called table glass, is made in a more mechanical way. Molten glass is poured out onto a smooth metal or graphite table. Then a heavy metal roller spreads it into a flat sheet, like rolling dough. This can be done by hand or with machines.
There’s also double-rolled glass. That goes through two rollers at once, kind of like an old-fashioned laundry wringer. This gives it a consistent thickness, usually around one-eighth of an inch, or 3 millimeters. After that, the sheet goes into an annealer so it can cool slowly and evenly.
This method started showing up around the 1830s. It’s still very common today. People often call this type "cathedral glass", but that name can be misleading. It has nothing to do with the medieval stained glass used in actual cathedrals, which was hand-blown, not rolled.
Flashed Glass
To handle regular wind pressure, architectural glass needs to be at least one-eighth of an inch thick, or about 3 millimeters. But when making red glass, the amount of colorant needed is so strong that, at this thickness, it barely lets any light through. It ends up looking black instead of red.
To fix this, glassmakers use a method called "flashing." They bond a very thin layer of deep red glass onto a thicker base of clear or lightly tinted glass. This creates what's known as flashed glass.
Here’s how it works. A light-colored molten glass gather is dipped into a pot of molten red glass. Then it’s blown into a sheet using either the cylinder or crown method. Once this technique was figured out for red glass, other colors started being made the same way.
Flashed glass has a big creative advantage. You can etch or grind away the thin top layer to reveal the clear or tinted glass underneath. This lets artists create detailed patterns or imagery without having to break up the design with extra lead lines. That gives them more freedom in how they design a piece.
Artists started using this method centuries ago. In the 1500s, detailed heraldic windows made heavy use of flashed colors to show complex coats of arms and creatures. Back then, they would scrape off the surface by hand. Later, people began using hydrofluoric acid to remove the top layer. That worked well but was extremely dangerous. By the 1800s, sandblasting became the safer method.
Islamic Stained Glass and Its Influence
Starting in the 8th century, Islamic culture had a huge impact on the art of stained glass. Glass was part of the architecture, bringing both beauty and function to mosques, homes, and public buildings. The demand for decorative glass in thousands of mosques, along with advances in science like optics and chemistry, helped push the craft into something bigger. What used to be a small trade turned into an industry that used new tools, new techniques, and a large workforce across the Islamic world.
Mass production of glass vessels began around this time. Islamic glassmakers used two main techniques: blowing molten glass into shapes, or cutting objects out of solid crystal. Syria, and to some extent Egypt, took the lead in glassmaking. Syrian makers in particular improved on older techniques, added their own styles, and helped expand the range of colors and patterns that could be used in glasswork.
Stained glass in Syria goes way back. Because the area was shaped by many cultures like Roman, Byzantine, and Islamic, it has a long history with glass art. Syrian glass is known for its precise geometric shapes and floral patterns, showing off the high level of skill and care used in each piece.
Modern Production and Innovation
Today, there are many glass factories around the world that still produce high-quality stained glass. Some of the most well-known are in Germany, the United States, England, France, Poland, Russia, and Syria. These factories still make hand-blown glass using the cylinder, disc, and crown methods. Others focus on rolled glass, like cathedral or opalescent styles.
Modern stained glass artists have access to centuries of knowledge. They study earlier masters and build on those traditions in their own ways. Starting in the late 1800s and into the 1900s, artists began developing new types of glass and experimenting with new ways of working with it. Tiffany glass and stained glass panels came out of that period, changing how stained glass looked and how it could be used.
Pot Metal and Flashed Glass
To add color to stained glass, the most common method is making colored glass from the start. Clear glass is melted down, and metal oxides are mixed into it while it's hot. The result is colored glass all the way through, known as pot metal glass. This method makes solid, richly colored sheets.
Another method, called flashed glass, is different. It uses a thin layer of colored glass fused to a clear base, or sometimes a different colored base. This was useful for expensive colors like red, which were often made using gold compounds. That kind of red glass was too dark and costly to use at full thickness, so flashing helped get the color without the weight or cost.
Glass Paint
There are also ways to add color and detail after the glass is made. Artists can apply lines, shading, and texture directly onto the surface of colored glass. These effects are fixed in place by lightly firing the glass in a furnace or kiln. One method, used across large areas, is silver stain. It created better yellow tones than anything else available during the Middle Ages.
Other techniques focus more on detail. The most common is black line painting, used to outline and define shapes. This method uses a mix called glass paint, also known as vitreous paint or grisaille. It’s made from powdered glass, iron, or rust filings for color, a binding material like gum arabic, and a liquid such as oil, water, or vinegar to make it brushable. Once applied to the glass, the piece is fired to burn away the binders and fuse the remaining materials to the surface. This leaves a thin, baked-on layer of black that becomes part of the glass.
Silver Stain
Silver stain came into use just after 1300. This is where the name “stained glass” actually comes from. It uses silver compounds, especially silver nitrate, mixed with binders and brushed onto the surface of the glass. After firing, it creates colors ranging from deep orange to pale yellow. When used on blue glass, it can even create greens.
The stain actually sinks into the surface of the glass slightly, making it more stable and long-lasting. The final color depends on how the glass is fired and cooled, though the chemistry is still not fully understood. By the 1400s, silver stain had become a cheaper option than full pot metal glass and was often used on its own, along with black paint, to add color to clear panels.
Silver stain and black glass paint didn’t mix well on the same side of a panel, so they were usually kept apart. The stain was applied to the outside face, and the paint on the inside. Each needed a different firing temperature, so they were likely fired separately. Interestingly, having the stain on the outer side seems to have helped protect the glass from the elements over time, though paint may have done the same.
Sanguine or Cousin’s Rose
Around 1500, another fired paint method showed up. It’s called sanguine, carnation, Cousin’s rose, or Rouge Jean Cousin, named after its supposed inventor. This technique uses an iron-based pigment that turns red when fired. Artists used it to highlight small areas, especially parts of faces and skin.
Later on, in the 1700s and 1800s, copper-based stains became popular. They worked in a similar way to silver stain but produced red tones instead. These copper stains added more flexibility for adding color to small parts of a design without switching out entire pieces of glass.
Cold Painting
Cold painting skips the firing altogether. It involves painting directly onto the glass surface using regular paints. This method was used despite warnings, including from the 12th-century writer Theophilus Presbyter, that it wasn’t very reliable. He claimed it worked, but time has proven otherwise. Most cold-painted details from medieval windows haven’t lasted. The paint flakes or fades because it was never fused to the glass.
Scratching Techniques
In addition to painting, artists also used scratching, or sgraffito, to create designs. This method involved layering glass paint over pot metal glass that was already colored. Before firing it in the kiln, they would scratch parts of the paint away to reveal the base color beneath. That’s how they formed images or carved out letters for inscriptions.
This was the go-to technique for inscriptions in early medieval stained glass. The result was white or light-colored text standing out against a dark, painted background. Later on, things changed. Instead of scratching away dark paint, artists started painting black letters directly onto clear glass.
Pot Glass Colors
These are the actual base colors of the glass itself, not added with paints or stains. They come from mixing metal oxides into the molten glass while it’s still in the pot.
Transparent Glass
Most soda-lime glass looks clear when it’s thin, but it’s not truly colorless. Tiny amounts of iron oxide in the mix give it a slight greenish tint. You don’t really see it unless the glass is thick or studied closely. When a clearer finish is needed, especially for plain window glass, additives are used to cancel out that green cast.
One of the most common additives is manganese dioxide. It reacts to form sodium permanganate, which can give the glass a faint purple or mauve tone. That soft tint is something you might notice in older homes in New England. Selenium can also be used for this purpose and gives similar results.
Green Glass
Very light green is just the natural color of basic transparent glass. But deeper greens come from adding more specific ingredients. Iron(II) oxide, for example, gives a bluish-green color. If you mix it with chromium, you get a richer green, like the kind seen in wine bottles.
To make even darker green glass, just increase the chromium. This kind of dark green works well for flashed glass. If you’re after a brighter, emerald shade, you need a mix of chromium, tin oxide, and arsenic. This gives the glass a vivid, jewel-like green that stands out more than the muted bottle greens.
Blue Glass
Back in the medieval period, glassmakers used cobalt to get that deep blue color you see in places like Chartres Cathedral. It only took a tiny bit, around 0.025 to 0.1 percent in soda-lime glass, to reach that bold blue tone.
There are other ways to make blue glass, too. If you add sulphur to boron-rich borosilicate glass, it turns blue. Copper oxide, when used at about 2 to 3 percent, gives it a turquoise look. Nickel can also create blue shades, though it depends on how much you add. A small change in concentration can change the color from blue to violet or even black.
Red Glass
To get rich red glass, glassmakers used metallic gold. It only takes about 0.001 percent. That’s what creates ruby glass, sometimes called "ruby gold." If the amount of gold is even lower, the result is a softer red that’s sold as cranberry glass. The way the gold particles spread out in the glass is what creates the color. This type of red glass is usually made from lead glass with added tin.
You can also use pure copper to make red glass, but the result is a dark, opaque red. This kind of glass is usually flashed, which means it’s layered. That makes it useful for decorative work like engraving and sanding, which was common in the late 1800s and early 1900s.
Selenium is another additive that helps create red and pink glass. When it’s combined with cadmium sulphide, it forms a strong, glowing red called Selenium Ruby.
Yellow Glass
One of the oldest ways to make yellow glass is by applying silver stain to the surface of the sheet. That method creates a yellow tone without mixing anything into the glass itself.
Another way is by adding sulphur along with carbon and iron salts. This combo creates iron polysulphides, which gives glass a color that ranges from pale yellow to almost black. If calcium is added to the mix, the result is a deeper yellow.
Titanium can also be used, but usually not on its own. It creates a yellowish-brown shade and is more often used to boost or brighten other colors.
Cadmium mixed with sulphur gives off a strong yellow. This is mostly seen in ceramic glazes. But cadmium is toxic, so its use comes with risks.
Uranium, in small amounts (between 0.1 to 2 percent), gives glass a yellow or green glow that can even fluoresce under UV light. Uranium glass usually isn’t radioactive enough to be harmful, but grinding or sanding it can make it dangerous to breathe in. In very high-lead glass, uranium can even turn the glass deep red.
Purple Glass
Manganese is the go-to for making purple or amethyst-colored glass. It’s been used since ancient Egypt and is one of the oldest known glass colorants.
Nickel can also create purples, along with blues and blacks, depending on how much is added. When mixed into lead crystal, nickel gives the glass a purplish tint.
White Glass
To make opaque white glass, tin dioxide is used along with small amounts of antimony and arsenic oxides. This type of white glass first came out of Venice, where it was used to imitate porcelain.
Later on, white glass became popular in the work of Louis Comfort Tiffany. He used it to make opalescent, streaky, and mottled designs that played with color and light in unique ways.
Design
The first step in making a stained glass window is getting a precise template of the window opening. This template might come from the building's architect or owner. The glass has to fit exactly into that space, so accuracy matters.
The subject of the window depends on where it’s going, what it’s meant to show, or what the client wants. A small sketch of the design, called a Vidimus, is made to show the client. Sometimes a scaled-down 3D model, called a maquette, is also created. The artist has to consider the structure of the window, the kind and size of glass they can use, the story or theme, and how they want to work.
If the design is a traditional narrative, it tells a story across different panels. A figurative design might show a row of saints or notable figures. Texts from scripture, mottos, or names of donors or people being honored might also be included. In more traditional layouts, the artist usually fills the background with borders, flowers, or architectural canopies.
A full-sized drawing, called a cartoon, is made for each section of the window. These sections are known as "lights." A small church window might have two lights and a few small decorative sections above. Bigger windows can have four or five. Cathedral windows, especially the large east or west ones, can have seven lights arranged in tiers, plus very detailed upper tracery.
In medieval times, the cartoon was drawn right on a whitewashed worktable. That drawing was then used as the pattern for cutting, painting, and assembling the glass. The full cartoon is then broken down into a patchwork map. Each little shape becomes a guide for cutting glass. The lines where the lead will go are also marked, since those lines are part of the final visual effect.
Selecting and Painting the Glass
Each piece of glass is chosen based on its color, then cut to fit its part in the design. To make the fit exact, the edges are trimmed using a special tool that can nibble off small bits. This is called grozing.
Details like faces, hands, and hair are painted onto the inner side of the glass. The paint is made from ground-up glass, lead or copper filings, gum arabic, and a liquid like wine or vinegar. In the past, urine was also used. This type of painting got more detailed over time, especially in the early 20th century, when it reached a peak in craftsmanship.
Starting around 1300, artists used silver stain made from silver nitrate. It gave a yellow tone that could range from light lemon to deep orange. This stain was usually applied to the outside of the glass, then fired in a kiln to make it permanent. It worked well for adding brightness to halos, borders, and decorative arches. It could also turn blue glass into green. By the mid-1400s, another stain called Cousin’s rose was added to bring warmth to skin tones.
In the 1500s, more stains were introduced. These were enamel-based, made with ground-up colored glass. At first, they were used for small designs like coats of arms. But by the 1600s, stained glass designs had changed. Instead of relying on cutting colored glass into sections, entire scenes were painted directly onto square glass panels. These painted panels were fired, then assembled like tiles.
Another decorative method involved painting one side of two thin glass sheets. The sheets were then placed back to back inside the lead. This allowed for techniques like Angel gilding and Églomisé, which could create reflective or gold effects visible from both sides. The painted sides stayed protected inside, so they wouldn’t get damaged or worn over time.
Assembly and Mounting
After all the pieces are cut and painted, they’re slotted into lead cames. These cames are H-shaped in cross-section, so the glass pieces fit snugly between the sides. Every joint is soldered together. To keep the glass stable and seal out weather, a soft, greasy cement is pressed between the glass and the lead. This stops any rattling and keeps the window tight. In modern work, artists sometimes use copper foil instead of lead.
When the finished window is installed, iron support bars are placed across it to hold its weight. The stained glass is then tied to these bars using thin strips of lead or, more recently, copper wire. Some of the oldest and largest Gothic windows use heavy metal frames called ferramenta to divide and support the design. This same method was later used in the Baroque period for large painted glass windows.
