How Stained Glass is Made

Most often associated with the religious scenes depicted on church and cathedral windows, stained glass has been around for centuries.

What’s more, eminent stained glass art has ranged from the perfume bottles of Rene Lalique to the lampshades of Tiffany & Co. founder Louis Comfort Tiffany and right up to the extraordinary sculptures of modern glass artist Dale Chihuly.

Yet, while the art produced has moved with the times, how stained glass is made has mostly stayed the same since the middle ages. So, how do they make stained glass? How do you make stained glass windows and how is stained glass art made? We’ll shed light on it all.

In 77 AD, Roman writer Pliny the Elder noted the accidental discovery of stained glass by sailors. Whilst this account is unverified, stained glass was around from at least the 1st century AD, becoming commonplace by the 7th.

Since that time, the popularity of stained glass has mirrored that of dubious fashion choices, falling in and out of favour at various points of history. One thing that can be said to have remained consistent is how stained glass is made. This has changed little since the middle ages.

The few exceptions to this include the invention of opalescent glass, patented by John La Farge on 24 February 1880, and the innovation of copper foil as an alternative to lead in stained glass windows patented by Sanford Bray of Boston in 1886.

First, a clarification as to the meaning of stained glass. Stained glass is coloured glass – that is glass which has a defined colour created during the glass-making process. This is different from other types of glass with colour where clear glass has colour added to it, such as:

• Painted Glass
• Laminated glass
• Stained glass repro

We’ll expound on these shortly, but for now we are dealing with stained glass.

So, how do they make stained glass? It’s produced during the manufacturing process by adding certain chemicals to what would otherwise be clear glass.

For a detailed account of glass making itself, see our article covering how glass is made.

For our purposes, suffice to say that one of the first steps in making glass is melting a mix of sand, sodium carbonate and limestone at a temperature of around 1000°C. To make stained glass, certain metallic compounds are added to this molten mix, turning the mix from clear to a coloured mixture and ensuring any glass produced is now a defined colour.

Different compounds added during this molten stage produce different colours. For instance adding:

• Selenium compounds makes reds
• Cobalt oxides makes blues
• Cadmium sulphide makes yellows
• Iron and chromium-based chemicals makes greens and browns

In factories, manufacturers make several colours of stained glass using carefully measured batches of raw materials. Blown glass or glass made in other ways can also incorporate these chemical compounds.

Stained glass is often confused with painted glass. The latter is clear glass, the surface of which is painted or stained using specialist materials such as:

• Vitreous paints: Composed of fine glass particles which are suspended in a liquid binder.
• Silver stain: This was used extensively for medieval church windows and is actually the etymological source of the name “stained” glass. This paint uses silver compounds such as silver nitrate, producing shades ranging from yellow to brown.

Such paints now come in a variety of colours and can be transparent or opaque. The use of paints or stains is often combined with that of coloured glass. For example, the makers of the aforementioned church windows may have used silver stain to paint fine details such as faces. Once painted, the glass is fired in a furnace or kiln, fusing the paint and glass.

How Stained Glass is Made by Machine

Some glass described as stained glass is in fact painted glass made almost entirely by machine. There are now very advanced computer numerical control – or “CNC” – machines able to swiftly etch and paint intricate designs on clear glass according to a digital design.

How Stained Glass is Made versus Laminated Glass

Laminated or “safety” glass is produced by placing a layer of vinyl between two sheets of glass. The vinyl is there to hold the glass in place should it shatter, but using coloured vinyl adds a decorative function, making the glass appear coloured.

Common Uses for Stained Glass

So, that’s how stained glass is made, as well as how clear glass can be coloured, but let’s see it in action. For instance, how do they make stained glass into windows? And how is stained glass art made?

So, how do you make stained glass windows? Generally, stained glass windows are made by combining pieces of coloured glass to create a design. These are held together by either lead or copper frames.

Making stained glass windows begins with creating the artwork for the design, first in a smaller version and then a full-sized one known as a “cartoon”.

This cartoon is transformed into a functional outline of the intended images, usually following the lines of the lead that will eventually connect the glass pieces. This is called the cutline and is essentially a template.

Placing the cutline on a table, pieces of glass are placed on top and cut according to the patterns using diamond or steel wheel tools. A lead or copper strip is then placed around the edges of the design to hold the glass in place. The lead is then soldered together, and the window is complete.

In terms of “how is stained glass art made”, the process is not dissimilar to that described for making windows. However, the process does depend to some extent on what is being made. Stained glass art is not necessarily flat like a window, and many artists blow their own glass to create curves for sculptures and other objects.

Generally, glass art requires a variety of tools, including glass cutting wheels, special pliers, soldering equipment, grinders and safety gear to shape and cut glass. In binding the glass together, lead, copper foil and epoxy are all options.

As with “how are stained glass windows made”, glass art is based on a drawn or computer generated design. The glass is cut and shaped using that design as the template. Much of the technique involved is learning how to cut curves and shapes. Using either lead or copper, the creation is soldered together. Otherwise there are glueing techniques.

And there you have it. We’ve shed light on the question “how do they make stained glass”. From “how are stained glass windows made” to “how is stained glass art made”, we hope how stained glass is made is now crystal clear.