Glass and Techniques
Initially, a distinction must be made between leaded and stained glass. The term ‘stained glass’ is often used when referring to all work done with coloured glass, whether it is actually stained or not. Stained glass is produced by a special enamel stain being applied to the glass, after which it is fired. Leaded glass is the use of glass (pot metal) which has already received its colouring during manufacture by the addition of metallic oxides and which need not be stained, painted, fired, etched, or treated in any other way. Therefore when making a leaded window the glass is purchased in its finished state, ready for use. The art of the craftsman is to choose the glass most suitable for the subject and to cut it into its correct shape for the required design.
– Process of Preparing a Stained Glass Window
After the design has been chosen, a full scale drawing of the window is made, representing the exact dimensions of the various parts. Care must be taken to ensure that the lead is placed where its appearance will heighten the effect of the glass by forming bold outlines to separate figures from the background, for example. A second drawing is traced from the first and this is called a ‘cutting drawing’. This is used to show the shape and size of each piece of glass to be used. The artist then marks on this second drawing the colours and tints of the glass to be used. Colour is possibly the most important feature and great skill is required when choosing colours and matching shades.
The next process is carried out by the glass cutter. The chosen sheets of coloured glass are cut into the required shapes, onto which the necessary lines and shading are painted, usually with a monochrome brown enamel. During this process, the pieces are placed together and temporarily fixed onto a glass easel. The parts to be stained yellow are covered with a preparation of silver which, when fired, produces a yellow effect. The pieces are then put into kilns on tiers of iron shelves. They are exposed to heat which is so powerful that it fuses the outlines and shading into the glass, making them a part of it. The ‘firing’ must be stopped at exactly the right moment, otherwise the brilliancy of the glass could be ruined. It must be allowed to cool down very gradually after being removed to the kiln, or it is likely to crack.
After this first firing in some cases it may be necessary to paint some of the pieces a second time. They then have to go through the process of firing again before they are ready for the glazier. The ‘cutting’ drawing is then placed on a large board and the pieces of glass laid on it in their proper position. The leading of the window now begins. Bands of lead with a groove down each side (known as cames) are used and bent and soldered together following the drawing. The pieces of glass slot into the grooves in the lead, uniting all the parts into a complete finished window.
The function of the lead came is to provide structural support for the glass and on occasion it becomes an integral part of the design. The black leading can emphasize and enhance the separation of the colours. The variation in the design of the lead came (see image below) can be decorative as well as functional, giving a cohesiveness to the varying thicknesses and textures of glass that the artist may bring together in one design.
Some of the more popular varieties of decorative glass include:
This is a handmade glass, and possibly the richest glass used. It is remarkable for the richness of its colours and variety and brilliance of its textures. The air bubbles in antique glass, which were at first the result of imperfect manufacture, are now appreciated as inherent qualities and give it its gem-like richness. It is manufactured in many different ways. The most common are:
(a) Pot Glass – this is glass of a single colour. It is known as ‘pot’ because it is made from one pot of a single colour. The pot is the vat in which the molten glass is kept in liquid form. The beauty of pot glass is its radiant depth of colour.
(b) Streaky Antique – this type of glass consists of, as its name implies, a basic colour which streaks of one or more colours running through it. These streaks are irregular, due to the fact that they are formed when two or more pots of glass are mixed together during manufacture. English streaky glass is transparent and so particularly suited to domestic windows.
(c) Flashed Glass – this consists of a thin layer of glass which is fused with another, thicker, base layer, usually the base being white or clear. This type of glass is particularly suited to stained glass artists who can etch onto the coloured layer revealing the base layer, producing some interesting effects. It is also useful because it allows several colours to be combined on one piece of glass.
Traditionally, this glass was manufactured in the United States by John La Farge and used by L.C Tiffany, but it is now made in Germany, Belgium and South Vietnam. Opalescent glass can be made of a singe colour, a few colours mixed together, or with a streaky, cloudy effect. It may or may not have a surface texture. Because it is opaque, it has the interesting quality that it can be seen by transmitted light e.g. the sun and reflected light. Transparent glass can only really be seen when illuminated from behind (a leaded window viewed from outside with no transmission of light through it appears flat and colourless).
Commercial or clear glass can be just as useful as textured or patterned glass. Too much patterned glass would detract from the actual design created by the lead. Clear glass can be used as a balance with patterned and textured glass or on its own as in the ‘trellis’ lead design (see image below).