Overlay stained glass looks like a leaded stained glass window but is built differently. Instead of many pieces of coloured glass held in lead came, it is a single sheet of glass with lead lines and colour applied to it. It is a modern product, and its history is not well documented. What follows is based on documented patents and on how the product is made now. It is not a complete history, and the first use of a technique often came earlier than its patent.
The problem it addressed
Traditional leaded stained glass is beautiful and durable, but it is heavy and flexible along the lead lines, so a large window needs support bars. It is labour-intensive and costly. It is unsuitable for curved surfaces and places with vibration. Safety rules also call for toughened or laminated glass in doors and low windows where people could be injured, and the patents below cite building codes that required a single pane of tempered or plate glass. A sheet of toughened glass cannot be scored, broken and leaded in the traditional way, and so a conventional leaded panel could not be made from it.
Early simulations
People had tried for a long time to imitate stained glass on clear glass. Patent literature of the late 1970s lists the earlier attempts: colouring clear glass with paints, varnishes, coloured gelatin, acetate, cellophane or tissue paper, and imitating the lead lines with adhesive-backed lead strips or lead emulsions brushed or squeezed on to the glass. These were widely used for decoration, but the same literature says they could not match the permanence of real stained glass.
Patents from 1978 to 1982
An American patent application filed on 20 November 1978 describes a simulated stained and leaded glass pane. Extruded lead strips are adhered to the front of a glass or plastic pane to form closed design segments, and coloured polyester sheet is bonded to the glass behind those segments. A division of that application became US patent 4,335,170, issued on 15 June 1982. A continuation of it, US patent 4,438,165, puts lead strips on both faces, lined up with each other, with coloured film and silk-screen painting behind. The patents list the drawbacks of authentic leaded glass given above, including the weight, the cost, the difficulty of fitting curved surfaces and the building codes.
This is the same idea, in an early form, as the overlay made today: lead lines and colour applied to a single sheet of safe glass, so as to look like a leaded window.
In the UK
Overlay reached the British market in the early 1990s and was becoming popular from 1991, and decorative bevels bonded to safety glass followed in 1992. Bevelled glass had until then meant traditional hand-leaded bevels, and the arrival of bevels bonded to a single sheet of safety glass opened up bevelled doors and panels to the same construction. The two products grew up side by side, and both answered the same need: the look of leaded and bevelled glass in a form that met safety glazing requirements.
Later developments
In the 1990s inventors tried casting clear resin onto a single sheet of glass in a mould to reproduce the relief of textured, leaded or bevelled glass. A patent application of December 1991 describes a decorative window of this kind, and its background lists earlier attempts with films, adhesive segments, lead strips, bonded bevels and printed designs. The aim was the same: to reproduce the effect of expensive handwork on a single pane.
Overlay stained glass today
The modern product follows the same construction. It starts with a single sheet of toughened safety glass. Lead lines are applied to the front in the pattern of a leaded design, and colour is applied as a durable colour film to the back, worked in mirror image from the reverse of the panel. The result can be supplied single or double glazed, and shapes, holes and edges are finished before toughening. Because every pane is made from a pattern, panels can be reproduced closely, which is useful where a traditional window has been broken and cannot be restored.
It is different from true stained glass, and honest descriptions say so: the colour is a film, not glass coloured in the furnace, and the lead is applied to the surface, not used as came. Its advantages are practical: it meets safety requirements, it is stronger and lighter than a leaded panel, it resists vibration and flex, it is easy to clean, and it can be fitted in doors and low windows where toughened glass is required. For these reasons it has been used widely in front doors and internal screens. Examples, including pieces that copy traditional designs, can be seen in the gallery, and the differences between overlay, leaded and traditional stained glass are explained on glass types.
Related reading
- Medieval stained glass and the origins of leaded lights
- How window glass was made, including toughened glass
- Learn: the craft of stained glass
On this site, see the glass type page for Overlay Stained Glass.
More glass history
- A Short History of Stained Glass
- Medieval Stained Glass and the Origins of Leaded Lights
- How Window Glass Was Made: Crown, Cylinder, Plate and Float
- Stained Glass from the Gothic Revival to the Twentieth Century
- Opalescent Glass, Tiffany and the Copper Foil Method
- The History of Brilliant Cut and Bevelled Glass
- The History of Acid Etched Glass
- The History of Sandblasted and Deep Carved Glass
- The History of Fused and Kiln Formed Glass
- Where Overlay Stained Glass Came From
Terms are explained in the Glass Glossary. The tools and methods used today are covered in Glass Tools and Equipment, and the types of glass themselves under Glass Types.
Sources and further reading
- US patent 4,335,170: simulated stained and leaded glass windows Patent record, issued 1982.
- US patent 4,438,165: simulated stained and leaded glass windows Continuation in part.
- US patent 5,944,862: methods related to making decorative glass windows Background on earlier simulation methods.
- British Glass: toughening, old techniques and new technologies
See also How Lead Came and Overlay Lead Are Made for how overlay lead is made.
See also Overlay Colour Films, UV Protection and Durability.