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Medieval Europe + Byzantine
Course: Medieval Europe + Byzantine > Unit 10
Lesson 1: A beginner's guide to Gothic artHow stained glass is made
The six basic steps in the production of stained glass
1. Cartoon
An artist would initially make a sketch of the overall composition of a window. Then full-sized drawings for the whole window or for different sections (panels) of the window were made. These full-sized drawings are called cartoons. Generally, the shapes of the individual glass pieces, the details to be painted, and the colors of the glass were indicated on the cartoon. In the early Middle Ages these were drawn on whitewashed boards.
An artist would initially make a sketch of the overall composition of a window. Then full-sized drawings for the whole window or for different sections (panels) of the window were made. These full-sized drawings are called cartoons. Generally, the shapes of the individual glass pieces, the details to be painted, and the colors of the glass were indicated on the cartoon. In the early Middle Ages these were drawn on whitewashed boards.
2. Cutting
Different colors of glass were chosen for separate parts of the design, and the outline of each piece was then painted on the surface with white lime wash. Pieces were cut into rough shapes using a dividing iron, the heated tip of which was applied to the surface of the glass, causing it to break.
The pieces were further reduced to the desired size with a grozing iron—an iron bar with a slot at each end that was used to chip away at the edges of the glass until the exact shape was created.
3. Painting
After the glass pieces were cut and shaped, they were painted with a pigment formed by mixing iron oxide and ground copper with powdered glass.
After the glass pieces were cut and shaped, they were painted with a pigment formed by mixing iron oxide and ground copper with powdered glass.
Wine, urine, or vinegar was added to help apply the pigment to the glass. This vitreous paint ranged from brown to gray to black. Once painted, the separate pieces of glass were placed in a wood-fired oven called a kiln. The heat of the kiln causes the vitreous paint to fuse permanently to the surface of the glass.
What is vitreous paint? Glass painters used a special paint made of glass particles suspended in a liquid binder—vitreous means "consisting of glass"—to paint the side of glass that would face the interior of the building. During firing, the glass particles in the paint melted and merged with the glass surface to create a range of brown and black tones.
The image below illustrates the main steps in painting more detailed sections of a window, such as the face of a figure. These examples copy the face of Jared from the Ancestors of Christ windows and were made by the Stained Glass Studio at Canterbury Cathedral for this display.
Step A: For detailed pieces such as faces, guidelines are painted on the back then broad layers of thin vitreous paint are added to the front with a wide brush.
Step B: The guidelines on the back are rubbed away and thicker paint is added over the thin washes on the front with a liner brush to create detail.
Step C: Thin washes are painted on the back to reinforce shading and give the illusion of greater depth. Once finished, the piece is placed in a kiln in order for the paint to fuse to the glass.
4. lead
Pieces of glass are held together with narrow strips of lead to form a panel. These strips are referred to as “lead came.” Lead is used because it is flexible and provides the adaptability needed for fitting around the various shapes of the glass pieces.
Pieces of glass are held together with narrow strips of lead to form a panel. These strips are referred to as “lead came.” Lead is used because it is flexible and provides the adaptability needed for fitting around the various shapes of the glass pieces.
5. glazing
“Glazing” is the term for assembling a panel of stained glass that can then be set into a window. After separate pieces of glass are painted and fired, they are placed in position on the cartoon and joined together with lead came to form a panel. In the Middle Ages, a combination knife and hammer was used for this process. The knife edge was used to cut the pieces of came and the hammer end was used to secure nails to the work board to hold the edges in place during assembly.
“Glazing” is the term for assembling a panel of stained glass that can then be set into a window. After separate pieces of glass are painted and fired, they are placed in position on the cartoon and joined together with lead came to form a panel. In the Middle Ages, a combination knife and hammer was used for this process. The knife edge was used to cut the pieces of came and the hammer end was used to secure nails to the work board to hold the edges in place during assembly.
The sections of came are then joined together with solder, an alloy of lead and tin that melts easily at a low temperature and sets quickly.
6. cementing
The panel is then cemented to help secure the glass within the leads and to waterproof the window. A semi-liquid cement is applied with a brush and then is covered with a layer of chalk or sawdust to absorb excess liquid. The medieval recipe for this cement is not known, though the main ingredients were probably crushed chalk and linseed oil. The panel is then scrubbed down with a dry brush until the cement only remains under the lead.
The panel is then cemented to help secure the glass within the leads and to waterproof the window. A semi-liquid cement is applied with a brush and then is covered with a layer of chalk or sawdust to absorb excess liquid. The medieval recipe for this cement is not known, though the main ingredients were probably crushed chalk and linseed oil. The panel is then scrubbed down with a dry brush until the cement only remains under the lead.
Scrubbing the panel with a dry brush
All images courtesy Dean and Chapter of Canterbury
Want to join the conversation?
- How would one get the various colours in the glass? I know that a silver stain would make a yellow/gold piece of glass, but what about the other colours?(14 votes)
- Source: Wikipedia.en In the 400-1300 medieval era the main method of staining glass was through control of temperature and oxidation. The iron and manganese salts in glass made with wood ash can give yellowish to flesh colours to red and brown and also blue and green depending on heating and venting conditions and impurities.
Late in the period copper filings may have been added to produce red, green and blue glass. Most likely, blue glass during the period in question would either have been poduced by wood ash or by soda, which can also produce blue glass.(13 votes)
- What property do urine, wine, and vinegar share that makes them a good binder for the vitreous besides mild acidity? Which was the most common to use, and if you don't mind me asking, why urine?(10 votes)
- Urine taken directly from the bladder is almost sterile, once it passes through the urinary tract it gets mixed with the bacteria living inside it. So don't assume urine is clean.(4 votes)
- What was a white washed board?(5 votes)
- Remeber, this was a time when paper was rare and very expensive, so whitewashed boards were a good re-usable medium for making marks for writing or drafting.
A flat, wide piece of wood was covered with a thin layer of plaster, it to make it relatively smooth, then it would be painted over with a white "wash" (thin paint) to create a writing (or in this case drawing) surface. After the image on a board was no longer needed, such as when the piece of work depicted on it was complete, the board would again be whitewashed to create a new clean drawing surface.
These boards would be used repeatedly,(5 votes)
- We read here below that lead was and is used between the panes of glass due to its soft texture and ability to flexibly hold the glass. Isn't handling lead dangerous though? Shouldn't we have a warning on this web page?
"Pieces of glass are held together with narrow strips of lead to form a panel. These strips are referred to as “lead came.” Lead is used because it is flexible and provides the adaptability needed for fitting around the various shapes of the glass pieces."(1 vote)- Yes, lead can be hazardous. People back then didn't know any better. As a matter of fact, the Romans routinely added ground lead to their drinks to sweeten them (it kind of makes today's concern about artificial sweeteners more poignant).(6 votes)
- Can you made a video about making stained glass, or is there some good one on the internet? It's very interesting subject.(2 votes)
- well, if you had the resources, I bet you could easily make a glass video. But there is definitely a video on the internet that was made by professionals(1 vote)
- The people in which made these presentations are very amazing and what they do. But, for the glass,what exacly does dry brushinfg the glass really do to help with the presentaion of the glass? And when they were a glass maker, were they far wealthier then common glass makers or are they the samwe person.(1 vote)
- Thank you for your kind words. The dry brush removes the excess cement. I am not sure what your final question is.(2 votes)
- I am working to attempt to make my own grozing iron. Where can I find dimensions or perhaps a schematic to work from? Also, what sort of metal is a grozing iron and Dividing iron made from (I would assume iron)?(1 vote)
- What kind of paint is used to "stain" the glass. Surely it's not regular paint because then you wouldn't be able to see through it.(1 vote)
- What is "stained" is not "painted". Here's a list of some of the things mixed into clear glass to make it colored: https://geology.com/articles/color-in-glass.shtml(1 vote)
- did they need to make just the glass to make the stained glass back in?(1 vote)
- You seem to be asking about how the colored glass was colored, whether or not it started out clear or not. The lesson does not speak to this point, merely stating that different colors of glass were chosen. Here's some information. Be careful, though. Check the footnotes, because it's from Wikipedia.
https://en.wikipedia.org/wiki/Stained_glass#Colors(1 vote)
- if the when it do's then why(1 vote)