Thirteenth-Century Lincoln Cathedral Stained Glass: Physico-Chemical Analyses of the the "Dean's Eye" Rose and South Lancet Window SG32
Creators: name: Author, Unknown
Publisher: name: University of Lincoln
Year: 2024

description: Currently, there is no comprehensive study and therefore understanding of procurement and glazing practices in 13th century AD England. The aim of this research is to determine the chemical composition, dating and the chaÃ®ne opÃ©ratoire of 281 fragments coming from original 13th century AD north Deanâ€™s Eye rose window and panel 4 of the south lancet window SG32 of the Lincoln Cathedral, England. It is to understand the extent of the original 13th century AD stained-glass fragments, its provenance and the history of the restoration. Furthermore, due to the lack of knowledge of the English 13th century AD glazing practices, the aim is to have a comprehensive understanding of the wider context these windows were made in and where the glass was procured from, in comparison with the glazing practices of coeval, antecedent and succeeding stained-glass windows in Britain and Europe. The bibliographic review, formalist method, archival research and physico-chemical analyses of the glass fragments and statistical analyses were the basis of this archaeometric study. The fragments were analysed by Handheld Digital Microscope (HDM), Optical Microscope (OM), Scanning Electron Microscope â€“ Energy Dispersive X-Ray System (SEM-EDS), Laser Ablation â€“ Inductively Coupled Plasma â€“ Mass Spectrometry (LAICP-MS), Micro-Raman Spectroscopy (Âµ-RS) and Contact Angle Goniometer (CAG). The OM revealed a new type G (with two sub-types G1 and G2) of red striated glass. The visual appearance and the chemical composition show an evolution of previous striated types (AD). The existence of striated glass in purple and yellow colour, and additionally, visible different refractive indices and presence of non-prominant striations (called stripes) of white glass, prove that glass mixing was not reserved only for red coloured glasses. The classification of the data has been done by expanding on the existing flowchart of the glass compositions by reviewing the published data and gaining new information about the dinstiction through PCA (Principal Component Analysis) and LDA (Linear Discriminant Analysis). Notably, the flowchart has to be used with flexibility as the bordering values need to be understood in relation to the rest of the chemical composition. The majority (181 out of 281 fragments) was proven to be original and have a typical medieval potassium composition dated to 13th century AD. Different glass-making workshops were hired to glaze Lincoln Cathedral, as fragments produced from both Central and North French glass-making workshops were found in the same panel. This might be due to the high demand of glass necessary to glaze the Cathedral, which could be the reason why the trace element data of the Lincoln Cathedral potassium glass do not match with other contemporary French cathedrals (done in the same laboratory) as shown by PCA. Only in a few instances, a direct association with the French cathedralsâ€™ fragments can be made. Possibly nine mixed-alkali (bordering with potassium composition) glass fragments are also original as this composition has been found in Lincoln Cathedralâ€™s panel 6 of SG32 lancet window, which is also dated to the 13th century AD. Newer insertions are evidenced with a terminus post quem of 14th century AD by potassium glass (red-flashed glass), including 15th century AD yellow flashed glass and 16th century AD sandwiched blue and purple flashed glass, 17th century AD HLLA and mixed-alkali glass, 19th century AD lead-based glass and 19th-20th century AD synthetic soda glass. The new flowchart revealed that some of the bordering HLLA glass can be classified as kelp (mixed-alkali) glass due to high strontium values (&gt;2000 ppm). The Lincoln Cathedral stained-glass has systematically been taken care of by the glaziers, restorers and conservators throughout the 800 years of its existence â€“ a care that successfully preserved the stained-glass in such a manner that it can provide outstanding information about the English history as it remains to be one of the extraordinary pieces of European Gothic Art.