Editing Stained glass (section)

===Selecting and painting the glass===

Each piece of glass is selected for the desired colour and cut to match a section of the template. An exact fit is ensured by "grozing" the edges with a tool which can nibble off small pieces. Details of faces, hair and hands can be painted onto the inner surface of the glass using a special glass paint which contains finely ground lead or copper filings, ground glass, gum arabic and a medium such as wine, vinegar or (traditionally) urine. The art of painting details became increasingly elaborate and reached its height in the early 20th century.

From 1300 onwards, artists started using "silver stain" which was made with [[silver nitrate]]. It gave a yellow effect ranging from pale lemon to deep orange. It was usually painted onto the outside of a piece of glass, then fired to make it permanent. This yellow was particularly useful for enhancing borders, canopies and haloes, and turning blue glass into green glass. By about 1450, a stain known as "Cousin's rose" was used to enhance flesh tones.

In the 16th century, a range of glass stains were introduced, most of them coloured by ground glass particles. They were a form of [[enamelled glass]]. Painting on glass with these stains was initially used for small heraldic designs and other details. By the 17th century a style of stained glass had evolved that was no longer dependent upon the skilful cutting of coloured glass into sections. Scenes were painted onto glass panels of square format, like tiles. The colours were then annealed to the glass before the pieces were assembled.

A method used for embellishment and gilding is the decoration of one side of each of two pieces of thin glass, which are then placed back to back within the lead [[came]]. This allows for the use of techniques such as [[Angel gilding]] and [[Eglomise|Églomisé]] to produce an effect visible from both sides but not exposing the decorated surface to the atmosphere or mechanical damage.