A stained glass windows begin life as a hand drawn scaled design, which is then hand-painted in watercolours, to capture the intensity of the glass colours. A stained glass design can also be born from a photograph, often a portrait or image proposed by my clients.
O nce the design has been approved, it is then scaled up to full size using a plotter. We then carefully apply the cut-lines to the design that correspond to changes in the glass mosaic and the structural requirements of this technique, paying careful attention that we enhance the window’s overall beauty. The cut-lines are just over a millimeter thick, and represent where the lead will be used. and the design often incorporates the different types of lead that are available on the market.
U sing the highest quality coloured glass available on the market, and sometimes even two different coloured glasses that will be stacked to obtain the required colours, the glass then hand cut, with utmost precision. To do this is we use diamond wheels to grind the glass until it fits perfectly into the cut-lines.
P ainting the glass is undoubtedly the most difficult phase in the creation of a stained-glass window. The pieces are painted with Grisalia, a technique which mixes a dark pigment, made from oxides and finely ground glass, with a special medium sometimes containing, essential oils, Arabic gum, or water depending upon the painting techniques being used.
The painting is built up in layers, each layer being baked in a kiln at 650°C. This firing bonds the Grisalia to the glass. Some designs call for coloured transparent glazes to be applied and these are fired at slightly lower temperatures.
We carefully layout the fired glass pieces on a light table to check the quality and shading of every individual piece, and the overall design.
T he lead strips have an ‘H’-shaped cross section. The lead is very malleable and is curved around the glass mosaic. The pieces are are then soldered together to hold the glassin position, ready for the cementing stage.
T he window is then cemented with a special lead cement made in the studio from chalk, linseed oil, a binding agent and a black pigment that will help darken the lead for polishing. The cement fills the spaces between the lead and the glass and hardens rendering the window weatherproof, for around 100 years. The window is then cleaned and brushed and the lead hand polished to perfection. The finished window is then ready, and when 100 years has passed the lead can be easily replaced and the window re-cemented, extending its life still further.