Stained glass, Medieval

Clusters of metal atoms can form colloidal suspensions. Colloidal clusters of copper, silver, and gold in glass are responsible for some of the vivid colors of stained glass in medieval cathedrals. Even aqueous suspensions of metal clusters are known (Fig. 8.45). 

The adhesive was developed for application to seal food containers with alumina foils and to seal glass plates. In this case, the vinyl polymerization step can be carried out by UV light radiation through the already mounted glass plates with a photoactive radical initiator to cure the viscous adhesive material. Another application of this material is the development of diffusion barrier containing protective coatings on medieval stained glasses (31). 

Schreiner, M., G. Woisetschlager, I. Schmitz, and M. Wadsak (1999), Characterization of surface layers formed under natural conditions on medieval stained glass and ancient copper alloys using SEM, SIMS and AFM, ]. Anal. Atomic Spectrom. 14(3), 395 03. 

Gillies, K.J.S and Cox, A. (1988a). Decay of medieval stained glass at York, Canterbury and Carlisle. Part 1. Composition of the glass and its weathering crusts. Glastechnische Berichte 61 75-84. 

The final group consists of 32 pieces of medieval glass from various sources which were part of the collection of The Cloisters Museum and were donated to the Corning Museum of Glass. Since the provenances of these specimens are not well established, the data for them cannot be used to characterize particular structures or glass workshops. These samples show the extensive variation in composition which does exist in medieval stained glass from different sources. Some, however, can be grouped upon the basis of similar composition. 

Vassas, C. D., Chemical, Thermal-Analysis, and Physical Study of Glasses of Medieval Stained-Glass Windows, Int. Congr. Glass, Artistic Hist. Commun., 9th, 1971 (1972) 241-266 (French). 

THE glorious medieval stained-glass windows of European cathedrals have been the subject of several chemical analyses to support conservation projects, to identify workshops and their practices, and to attempt the association of colors with specific metal ions in various oxidation states. However, little information of this sort has been generated from the beautifully decorated, enameled, and gilded copper ecclesiastical objects used in medieval cathedrals that are recognized under the generic name of Limoges enamels. 

Major, Minor, and Trace Element Analysis of Medieval Stained Glass by Flame Atomic Absorption Spectrometry... 

The purpose of this chapter is to outline the development of a reliable procedure that can be used to determine the elements that are the most significant constituents of medieval stained glass. The scope, accuracy, and precision of the method are evaluated in terms of standard glasses the archaeological significance of the analyses, in terms of the criteria... 

Interferences. Each element under consideration was investigated for the effect of interference on the determination of all other elements. The effects of titanium, tin, and antimony, not analyzed in this study but known to be present in medieval stained glass, albeit at levels less than 1%, were also investigated. Silicon was not considered because it is removed by volatilization at the dissolution stage. 

Two additional hydrofluoric acid methods have been reported (1,2), and are similar to that described above. The method of Hughes et al. has also been the subject of two comparative studies relevant to the analysis of ceramics (2,31). Techniques that retain silicon have been discussed (1,2) and involve either fusion with lithium metaborate [or sodium carbonate (2)] or high pressure dissolution in a PTFE bomb. An alternative high pressure method, developed by Price and Whiteside (32), was evaluated in the course of this investigation but was found to be unreliable for stained glass of medieval composition in many experiments dissolution was incomplete. Attempts to modify the procedure by varying the prescribed dissolution parameters produced insufficiently consistent results although superior conditions were established (Table I). 

The importance of interferences in AAS has been stressed (2). We have observed only chemical interferences for stained glass of medieval composition. The interference due to ionization of sodium, potassium. 

Standard Classes. The accuracy of the AAS method has been assessed by analysis of the 10 synthetic glasses prepared for the European Science Foundation (ESF) and of Corning Standard D, which also served to determine the precision of the results. These standards were selected in preference to glasses with better-evaluated specifications because their compositions are representative of medieval stained glass. 

Table IV. Analyses of Medieval Stained Glass Fragments, Excavated from Scottish Sites...

Although the salient features of medieval stained-glass-making techniques and composition many... 

The AAS method has several limitations. For the trace elements, particularly the colorants cobalt and nickel, the dilution factor required for analyses of 12 elements by continuous nebulization places these elements close to the detection limits for flame AAS. More accurate data on these and other trace elements are necessary before conclusions can be drawn on the source minerals used to impart color. Phosphorus, a ubiquitous minor component of medieval stained glass, has not been determined by AAS in the course of this work, but has the potential to provide key information on sources of plant ash. A full understanding of the colorant role of the transition metal elements is not possible on the basis of analysis alone UV-visible spectroscopy, electron spin resonance spectrometry, and Mossbauer spectroscopy, for example, are necessary adjuncts to achieve this aim. The results of the application of these techniques and the extension of the AAS method to trace element determination by pulse nebulization and furnace atomization will be addressed in future reports. 

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