Journal Of Glass Studies
Two examples of technical and physical evidence of early-medieval stained-glass workshop practices are examined. The examples comprise a group of 13 panels of French grisaille from various buildings, which date from the 1250s to the 1270s, and panels representing three standing bishops from the band windows in the Norman abbey church of Evron, which date from the second decade of the 14th century. All of the panels are now housed in the Glencairn Museum in Bryn Athyn, Pennsylvania. The first group seems to provide an example of “ghost images”—corrosive imprints resulting from vaporized deposits transferred from one piece of glass to another when they were fired in the kiln—suggesting that the panels were stacked in the kiln. The second group reveals a number of painted marks that would facilitate sorting and assembling pieces of repetitively designed architecture for leading an individual panel. Such “ghost images” and sorting marks appear to document a desire to facilitate the assembling and arranging of repeated, modular pieces of fired ornamental glass in order to save time and money in the production of stained-glass windows.
Michael Watt Cothren.
"Production Practices In Medieval Stained Glass Workshops: Some Evidence In The Glencairn Museum".
Journal Of Glass Studies.