Editing Stained glass (section)

===Glass paint===
[[File:Magi Herod MNMA Cl23532.jpg|thumb|[[Grisaille]] stained glass (15th century)]]
Another group of techniques give additional colouring, including lines and shading, by treating the surfaces of the coloured sheets, and often fixing these effects by a light firing in a furnace or kiln. These methods may be used over broad areas, especially with silver stain, which gave better yellows than other methods in the Middle Ages. Alternatively they may be used for painting linear effects, or polychrome areas of detail. The most common method of adding the black linear painting necessary to define stained glass images is the use of what is variously called "glass paint", "vitreous paint", or "[[grisaille]] paint". This was applied as a mixture of powdered glass, iron or rust filings to give a black colour, clay, and oil, vinegar or water for a brushable texture, with a binder such as [[gum arabic]]. This was painted on the pieces of coloured glass, and then fired to burn away the ingredients giving texture, leaving a layer of the glass and colouring, fused to the main glass piece.<ref>[https://boppardconservationproject.wordpress.com/2013/05/03/facts-about-glass-early-glass-painting/ "Facts about Glass: Early Glass Painting"], Boppard Conservation Project – Glasgow Museums; Historic England, 287-288</ref>