Anglo-Saxon Glass - Window Glass

Window Glass

With the introduction of Christianity in the early 7th century and the building of ecclesiastical structures the amount of window glass also increased. Window glass, some of which was also coloured, has been identified at more than 17 sites, of which 12 are ecclesiastical. Hundreds of window glass fragments have been found at Jarrow, Wearmouth, Brandon, Whithorn and Winchester. This evidence supports the historical records, such as Bede’s account of Benedict Biscop’s importation of glaziers from Gaul to glaze the windows in the monastery at Wearmouth in AD 675.

Most Anglo-Saxon window glass is thin, durable, bubbly and when colourless has a pale bluish-green tint. Many of the ecclesiastical sites have also produced strongly coloured glass from the 7th century onwards. Analysis of window glass from Beverley, Uley, Winchester, Whithorn, Wearmouth and Jarrow, has revealed that the majority was again a soda-lime-silica glass but it has also revealed that the composition is different from that of vessel glass, with lower quantities of iron, manganese and titanium suggesting a different source of raw material, possibly from The Levant. The analysis also revealed more about the transition from using soda as a flux, to potash.

Window glass in antiquity could be produced in three ways; cylinder blown, crown manufacture or cast. In Anglo-Saxon England there is evidence for all three types of methods being used. The vast majority of glass windows were produced by the cylinder blown method, although possibly on a smaller scale than the classic methods mentioned by Theophilus. Some Anglo-Saxon window glass was produced by the crown method and at Repton thick pieces of window glass with swirling layered surfaces were possibly made using the cast method.