If you are thinking of commissioning a stained glass window it may be helpful to understand some of the terminology and techniques involved as these will affect both the character and cost of the finished work. The raw material, sheet glass, is manufactured by skilled craftsmen and supplied to stained glass artists from an ever-dwindling network of suppliers across the country.
Manufacturing has all but died out in the UK, the majority now being sourced from Europe, China and the USA. High quality mouth blown glass is costly and scarce with the variety far more limited than that available in the past. Helen is fortunate to have amassed a substantial collection of old sheet glass to draw on in her work.
Choice of glass:
Machine rolled glass
This can be clear or coloured glass mechanically ‘rolled’ (a little like making pastry!), with a variety of textures. This distorts the light making the glass useful to afford privacy, for example in a front door or bathroom window. Because it is machine made it is comparatively inexpensive and consistent although perhaps rather bland in quality.
Antique Glass
You may consider this as glass made in the old fashioned way, mouthblown and consequently less uniform. Antique glass often contains tiny bubbles (seeds) and or rippling lines (reams), making it much more delicate and delightful to the eye. It will still vary in quality with the very best, and consequently most expensive, until recently, blown in England, full of irregularities and character.
Flashed Glass
A more complex antique glass, molten glass is ‘gathered from the pot’ then dipped into a second colour, the resulting blown sheet thus having one colour covered with a thin veneer or ”flash” of the second colour. Because the flash can vary in thickness across the sheet it may impart a wonderful variation in hue. Acid etching or sandblasting can then be used to erode through the flash enabling all manner of figurative or decorative detail.
Streaky Glass
This is a flashed glass where through the skill of the glass blower, a second, even third or fourth colour may be spread in swathes across the sheet – the Rolls Royce in antique glass! Cheaper machine made alternatives are available which can be adequately pleasing in domestic windows.
Opalescent Glass
This is glass given a milky consistency. Developed in the United States famously by Louis Comfort Tiffany and John La Farge, it was commonly used in lampshades. High quality American imports come in a spectacular array of colour combinations and textures and whilst primarily intended for lamp work, used judiciously, it can create interesting effects when incorporated into traditional stained glass windows.
Stained Glass Techniques:
Glass Painting
Not to be confused with cold acrylic paints used on decorative wares, this is vitreous paint fired onto the glass and thus rendered permanent. Normally in shades of black or brown, it can be used for linework or ”tracing” of figurative detail, as a wash or ”matt” for areas of light and shade or more freely to give a host of decorative and textural effects. Any colour in a window will come from the glass itself with line and shade applied in paint.
Enamelling
Similar to painting on ceramics, coloured enamels can be mixed and fired onto the surface of the glass. Very popular in the eighteenth century when it was fashionable to copy old master paintings onto glass, it still has interesting contemporary possibilities although perhaps without the intensity achieved with coloured glass.
Silver Stain
Invented in the early fourteenth century, oxide or chloride of silver was found to stain glass in various shades of yellow, from a pale lemon through rich amber to a reddish brown. The story goes that a glass painter dropped his silver ring in the kiln and it left a silver stain on the glass. Relying on the chemistry of the glass, stain is notoriously fickle but can give glorious effects when used with skill or by happy accident!
Acid Etching
Hydrofluoric acid can be used to erode a ”flash” from the surface of glass. Used traditionally, for example in heraldry, figurative detail may be drawn within a single piece of glass, a golden lion on a red ground or, used more freely may impart a fabulous variety of texture and hue. In this example, two pieces of etched flashed glass are overlaid enabling four colours in the peacock’s crown. Acid is extremely corrosive and a dangerous pollutant so sandblasting can be used as a safer method of eroding through a flash.
Sandblasting
As well as its use to erode through a flash as already described, sandblasting may also be used in different ways to give a frosted effect, often patterned, to the surface of translucent glass.
‘Capturing Magic: How Stained Glass is Made’
This short film commissioned by the Stained Glass Museum in Ely, describes the processes through which a traditional stained glass window is created: