The stained glass process

The process of designing and making stained-glass windows is incredibly labour-intensive, and the labour is almost entirely manual. There are very few mechanical aids, which makes it something of an anomaly in this all-electronic, high-technology age. It is a process that has changed very little over many centuries.

It starts with design, and here too my preferences are quite low-tech. I do not use any computer-based tools at the design stage, but much prefer the tactile feeling of pencil and paper, and good old traditional watercolour paints. Many things need to be taken into account at the design stage - the building in which the window will live, the purpose of the window, the way the light will strike it, and of course the client's own ideas and wishes.

Working on a design

A completed design

I believe it is very important to design and build windows that are structurally sound, and this too must be considered right from the start. The most beautiful window will be a liability if it is not also structurally sound.

Once the design is set, the next stage is to draw a full-size cartoon, which will be used as a pattern for cutting out the glass. If there is to be painting on the glass, a glass easel is then made up from the cartoon. This is a sheet of clear glass with the design transferred to it from the cartoon. It is supported in a vertical position, and as the glass pieces are cut they are stuck onto it using blue-tack. The cutting itself is done on a light table, using the cartoon as a guide. Piece by piece, the window is assembled on the easel, in preparation for painting. If there is not to be painting, the glass easel is normally not necessary.

Drawing the full-size cartoon

Transferring the design from the cartoon to the glass easel

The completed easel

Cutting out the glass over the cartoon, on the light table

Mounting the cut glass on the easel

If there is to be painting on the glass, this will be the next step in the process. There can be several layers of paint, working from the lightest colours to the darkest. Each layer must be fired in the kiln. Many paints will change colour during the firing process, so it takes a good deal of experience to get the right density of paint before firing it.

Painting on the glass

Painted glass laid out in the kiln ready for firing

Once all painting is completed and fired, the window can be assembled. This is normally done on a board (particle board or MDF), over the cartoon which again serves as a template. Nails are tapped into the board to hold things in place - horseshoe nails are particularly good for this, as they have good sharp points and one side is completely flat.

Assembling, or "leading", the window over the cartoon

Assembly complete - soldering the joints in the lead

The final step in the process is to cement the window to seal it against weather, and fix the glass pieces in place - it also makes the window much stronger. It involves mixing up the putty-like cement mixture, then working it into the very small space that is left where the glass sits in the channel in the lead. It is a very important step, but also a messy and fairly unpleasant one. It is quite physically demanding to work the cement into the recesses under the lead where it has to go. It must be done thoroughly, or the window will not be weatherproof.

Working the cement in under the lead

A final going-over with whiting to clean things up

That completes the process of making the window, but of course there is still the installation. Depending on where the window is to be installed, this can also be a complex and physically-demanding task, and may involve scaffolding, a cherry-picker, and/or a lot of clambering up and down ladders.