Heritage and Landscape

Survey of Exeter Cathedral Stained Glass using portable X-ray fluorescence (pXRF)

Glassworking in England from the 14th to the 20th Century is a detailed examination of the English glass industry with an emphasis on the archaeological evidence. Author David Dungworth is an archaeological scientist with over 25 years’ experience of studying early metal and glass industries, and below discusses a recent survey of some of the stained glass windows at Exeter cathedral.


As set out in my recently published book, the use of portable X-ray fluorescence (pXRF) allows the chemical analysis of in situ window glass. The chemical composition of the glass reflects when it was made and so can help identify original glazing as well as later replacements. Earlier in 2019 I undertook a survey of some of the windows at Exeter cathedral. Over 500 panes or quarries were analysed using pXRF. This showed that while some windows are essentially medieval (with later repairs), some windows are composed almost entirely of 19th century (or later) glass. The later glass was carefully produced to imitate the earlier medieval glass and is almost indistinguishable on visual grounds.


Photograph of a panel from EII


Same panel colour-coded to show date of manufacture










The first panel shown here (from window EII) is made up of almost entirely of medieval glass: two shades of green are used to represent two compositional groups, both of which were made in the medieval period. There are two (18th-century?) repairs: one a kelp (or seaweed) glass (red) and one a flint glass (white). Additional glass has also been added to a border at the base (buff colour, 19th or 20th century) to make the panel fit the space. This panel appears to have originally been designed for a different window opening but has been moved into this window at a later date.


Photograph of a panel from S3


Same panel colour-coded to show date of manufacture










The second panel shown here (from window S3) appears to contain no glass produced before the 19th century, despite the fact that the glass has been selected, cut and decorated to match adjacent panels that do contain at least some medieval glass. It is likely that this window was subjected to extensive repairs in the 19th century (or later) which included the manufacture of new panels. Nevertheless, the glaziers went to considerable lengths to make sure the new glass matched the original glass; including stipple painting to give the impression of pitted corrosion.

For more information on Glassworking in England from the 14th to the 20th Century, please visit our website.

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