History of stained glass

The following article by Amy McCarthy was published in Making Magazine in February 2011

Introduction to Stained Glass

Stained glass has been enthralling and inspiring people for a thousand years. The production of glass goes back to Egyptian times; however, it was not until glass blowing superseded moulded glass that it was effectively used in windows and stained glass was first seen in Northern Europe in the 11th Century. Stained glass was integral to religious teaching through out the Middle Ages; few people could read, so the scenes depicted in stained glass illuminated the sermon of the priest with the characters of the bible, whilst the magical qualities of light shining through glass added to the spiritual experience. In the intervening centuries stained glass moved from ecclesiastical to secular architecture and by the late 19th Century stained glass production was at its height; factory production reduced glass prices and was available in a myriad of colours, so even modest dwellings had stained glass panels. The rise of UPVC has led to the decline of this craft since WWII, however, glass artists are still working and rising to the challenges of the modern world, creating a new contemporary style of glass art and increasingly my work is incorporated into double glazed units.

The colour of glass is created by adding pigments and chemicals to the molton glass. Glass making is a highly skilled craft but basically the molton glass is rolled flat and cooled. The term stained glass comes from the black enamel paint and silver stain which can be painted onto the glass and then fired in the kiln to bond with the glass; contemporary techniques include etching and sandblasting.

The process of making a traditional stained glass window has changed little since 11th Century and here I use a recent diamond shaped front door panel commission to illustrate this process. Having prepared a range of designs around the clients design brief the chosen design is then translated to an accurately measured full size template. The next step is to cut the glass. Using a diamond wheel glass cutter I cut each piece of glass to the exact shape and ensure it sits inside the cartoon outline. Cutting the glass accurately is imperative; if pieces need to be made smaller I nibble at the edges of the glass with gronzing plyers.  Next I made a frame for the diamond shape from wooden batons fixed to a chip board base.

Lead came comes in various thicknesses and in an H section, so it has chanels each side of a central lead strip. The lead for 2 of the side edges of the panel is laid first and these are usually thicker strips of lead to give the window strength and create a border. Then the glass is slotted in, following the template and held in place with horse shoe nails hammered into the wooden board. Lead is a fantastically malleable material and bends easily around the glass. A special lead knife is used to precisely cut the lead to meet with the next piece of lead, and slowly the jigsaw builds up by adding glass and continuing to add the strips of lead.  Once all the pieces are in place and surrounded by the lead border tallow is applied to all the lead joins and a tin/lead mix solder is melted onto the joins using a soldering iron to knit the lead together. This process is done to both sides of the window and turning the panel over when only one side is soldered is a tense moment in any glass studio!

Next cement is forced into the spaces between glass and lead, to strengthen the panel and make it water tight. Once this cement has hardened it is incredibly strong and all the traces of it need to be cleaned off the lead and glass using whiting (abrasive powder) and lots of elbow grease. To finish a patina acid is washed over the window to darken the solder joins and polish is applied. With a bit of care this panel will last a lifetime!