Stained glass has been in use in churches since the 12th century and the techniques have changed little since then.  Pieces of glass, stained various colours by the addition of metallic oxides are pieced together in a pattern and held together with soldered lead strips.  The glass is then made waterproof within the lead framework with mastic.  The glass can be further decorated by painting on designs which are then sealed on to the glass during a firing process.  Certain colours would be too dark if used through the glass, such as red, so white glass will be dipped in the coloured glass, blown and then rolled flat.  The cooled glass can then by further decorated by grinding patterns to removed portions of the coloured film. 

The craft of making stained glass continued to to 17th and 18th centuries when it showed signs of dying out.  During the Victorian religious revival and the consequent church building boom, the skills were relearned and the stained glass maker's art reached new heights of skill and beauty.   The craft remains in use today and modern artists frequently work in the material.

Selby Abbey has glass dating back to the 13th century and forward into the 20th century.  As part of the current major restoration programme, windows are being repaired and three skilled craftsmen are using medieval, Victorian and modern material, sometimes in the same window.  Some of Selby Abbey's beautiful examples of stained glass are shown below.

This window, high in the clerestory, has been repaired as part of the current restoration.  The diamond shaped pieces include some from the early church, some Victorian glass and some modern glass.

A detail from the Jesse or East window, showing King David, the Psalmist.  This window, though much restored, dates back to 1330.

From the same window, Jesse himself.