Evidence of stained glass windows can be found as early as the 7th century in England, the earliest of which dates from 675 AD when Benedict Biscop imported French labour to glaze the windows of a monastery he was building in Monkwearmouth. Much of the technical and artistic development behind the stained glass window movement in North Western Europe arose during the Middle-Ages, with the desire to glorify Gods, Saints and Generals in lavishly decorated cathedrals to educate a largely illiterate populace on religious teachings and glorious victories. Not to mention the need to keep congregations sheltered from the elements.
It’s like a jigsaw puzzle. People either love them or hate them, I loved jigsaws as a kid which is probably why I ended up in stained glass windows
Shelter was and is a key design consideration for stained glass window makers. They must be able to withstand the wind and rain but also, especially in larger works, must support their own considerable weight of glass and lead. Today the use of coloured glass can be found almost everywhere, in contemporary design, architecture, wine glasses and lampshades.
Stained glass has a number of aliases and production techniques, functioning as an umbrella term for a myriad of glass practices, depending on the place and time of manufacturing. Glass panels can be painted with enamels or reactively stained using metal salts and minerals and then fired in a kiln to preserve the coloured translucent effect.
Humans Invent tracked down Jonathon Hunt, one of the UK’s prominent stained glass window and leaded light experts based in South East London at Clockwork Studios, about the rennovation and restoration techniques needed to keep these impressive pieces of art in tip top condition.
Hi Jonathon, could you tell us about your background and personal history of working with stained glass?
I first started making what is known as terrariums, which are greenhouses. They originated from the Darwin voyages to the tropics where they needed a way of transporting plants and species back to England.
Leaded lights and stained glass comes under the same banner
I started on a 3 dimensional basis, making these terrariums. Then I went on to manufacture leaded light windows for a glazing company and from there I moved on to stained glass windows, which I’ve been doing now for 30 years.
Can you run us through what stained glass actually is?
Stained glass is a generic term. Leaded lights and stained glass comes under the same banner, but staining itself is a particular yellow stain which you use. It is not like enamel – which is how you paint on glass – but staining. The yellow stain actually reacts with the glass and literally stains it.
Enamels and paints will need to be touched up and replaced but the staining will remain. Again, that is just one type but purists will say that is the genuine form of stained glass.
Is stained glass window work in decline? Or is it as strong as ever?
The thing is, as a society we have hundreds of thousands, if not millions of terraced houses that have stained glass windows in their front doors. So you are looking at a period from Victorian times right up to the end of the 50s, then the 60s came along and it was all modern after that.
Can you run us through the processes of making and restoring a stained glass window?
I’ll take you through a typical restoration process for a stained glass window. Firstly you ascertain what needs to be done and go through the journey with the customer.
Then essentially you take the window out of the frame, either a wooden frame or, with churches and stone buildings, the windows are set and glazed within the stone, so you would have to chip away the mortar. Once the window is removed we can then board or temporarily glaze the window space and we take the window back to the workshop to take a rubbing.
Once the rubbing is done I remove the glass and recycle the old lead. From the rubbing, which is your basic template, just like a jigsaw puzzle, you place the panes of glass in the right order and map the trace lines of the heart, which will be your template for putting the window back together again.
Before piecing the work back together you obviously have to clean and replace any dirty or damaged glass, which is a usual occurrence when it comes to restoration, along with wear and tear on the leads and the cement.
The yellow stain actually reacts with the glass and literally stains it
Stained glass needs to be carefully cleaned using ionized water and a shammy leather. There is a difference between leaded lights and stained glass. Stained glass is where the colours are actually painted on and then fired in the oven, which is a very delicate process. When cleaning you need to keep as many of the original painted features as possible.
Hunt says stained glass is really like a jigsaw puzzle.
Once the glass is cleaned it is placed in a jig, with a border lead which is generally 12mm thick. Then you place and attach the glass onto your template with a lead ‘came’ which is what holds the lead together, along with soldering joins on the glass and lead. The soldering flux then needs to be washed off, which can stain the lead. Some people use tallow which is a mixture of rendered animal fat and resin. Personally I use a plumber’s flux which is non toxic and doesn’t stain.
Next comes the mucky part: the cementing of the piece which, depending on the complications of the pattern takes a long time. The cement itself is based on the dust of old cement, black vegetable die, linseed oil and white spirit. Whiting (calcium carbonate powder) is then used to dry the cement, which is left for a day and then you have a finished panel which you refit.
Alot of people say “Oh, stained glass that’s really arty etc” but then I say stained glass is really like a jigsaw puzzle and then they get it. People either love them or hate them, I loved jigsaws as a kid which is probably why I ended up in stained glass windows.
If a stained glass window needs completely replacing do you fire that in the studio yourself?
I actually sub that work out. I have done it and can do it but it takes an awful long time and its best to do it if you are making them day in day out. It’s an incredibly long process.
What is the biggest project you’ve ever taken on?
The John Piper window at St. Peter's Church Firle Place.
I did one last year which was an 11-year-old girl’s bathroom. I had to design a bespoke window from scratch of Lancelot and Guinevere based around old Arthurian myths and legends. I used the classic illustrators of those stories as inspiration. It actually came together very nicely.
Have the techniques changed much over the ages?
I’ll tell you what, this work has been going on for a thousand years if not longer. The old methods and techniques really haven’t changed. It is just like a craft such as carpentry or stone masonry. Obviously now there are machines like sand blasters that can speed processes up such as shaping glass which would have taken months or years of forming with pliers before such technology.
