Ightham Mote, Ightham, Kent: Portable XRF Analysis of the Window Glass
Author(s): David Dungworth, Brice Girbal
The analysis of historic window glass has been undertaken with the purpose of determining the age the glass. Previous research has established how changes in raw materials and window glass manufacturing technologies are manifested in the composition of the glass and that this can be used as the basis for a glass dating technique. This report contains the analysis of 1,939 panes of window glass from Ightham Mote, Kent. All of the analyses were carried out in situ and non-destructively using a portable X-Ray Fluorescence (pXRF) spectrometer. The report contains a discussion of the problems encountered in attempting to obtain reliable data on light elements with pXRF, especially the effect surface corrosion. These problems have prompted a greater reliance on heavy elements, such as rubidium and strontium, whose detection is less affected by surface corrosion. The pXRF data has been analysed to show that 10% of the analysed panes are made of forest glass, that is glass manufactured before the last third of the 16th century. These panes may represent original 14th-century glazing or the alterations and addition to the windows commissioned by Sir Richard Clements in the early 16th century. Chemical analysis indicates that 34% of the analysed panes are made from high-lime, low-alkali (HLLA) glass and so likely to have been manufactured towards the end of the 16th century or during the 17th century. Only 3% of the analysed panes were made using seaweed ash and so datable to the 18th century or first three decades of the 19th century. The remaining 53% of the analysed panes were made using synthetic soda and so datable to the years after c1835. The distribution of the forest and HLLA glass suggests that many of these panes have been re-set and that some may even have been moved from window to window, room to room and possibly building to building.
- Report Number:
- 96/2011
- Series:
- Research Department Reports
- Pages:
- 120
- Keywords:
- Glass Post Medieval
