Medieval enamels

Fricke, H.C., O Neil, J.R. and Lynnerup, N. 1995 Oxygen isotope composition of human tooth enamel from medieval Greenland linking climate and society. Geology 23 869-872. 

Fig. 8. Fluorine scans obtained by PIGE Fluorine-containing soil water enters the tooth mainly through the nerve canal into the pulpa. The cementum also readily takes up fluorine which slowly diffuses into the dentine, while the enamel crown forms a barrier. Fluorine enters a long bone as well from the periosteal surface as from the marrow cavity. The thickness of the bone wall does not influence the shape of the diffusion front itself, but limits the time window where age determination is possible, as the profile becomes flat much faster. (Human molar, Seeberg BE, Switzerland, 3750 bc, and human tibia, grave 132, Buren a. A. BE, Switzerland, medieval).

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. 

England (1) reviewed the literature of the chemistry of medieval glass and enamel, including excerpts from the writings of Theophilus, the medieval scholar. Copper is mentioned as an important colorant. 

Brill (6) summarized the information on the chemical basis of medieval glass colors as follows red/orange opaque enamels, cuprite (Cu20) with lead additions beneficial for opacity white opaque enamels, either tin oxide opa-... 

The present study suggests that the coloring agents in the enameled copper cross examined, judged to be medieval from stylistic considerations, may be primarily compounds of copper. However, there was also a strong back-... 

On the basis of XRF studies, the colors of a typical medieval Limoges enamel cross are attributable to copper compounds added to the glass composition,... 

On the basis of XRF studies, the enamels of a medieval reliquary are recognizably different, a fact suggesting that the object was made in a different workshop tradition, although its the stylistic features are typical of enameled medieval objects. 

Williams, W. S. Hopke, P. Maguire, H., Composition of Medieval Limoges Enamel, 1984 Symposium on Archaeometry Smithsonian Institution Washington, DC, 1984 Abstract, p 157. 

Fig- 7.7 Climatic changes over the last 1,400 years revealed in Greenland ice cores document periods of warmer and colder conditions than today. The Medieval Warm Period witnessed the expansion of the Vikings across the North Atlantic while the Little Ice Age documents a time of cooler conditions and declining harvests. The carbon isotope evidence from human tooth enamel shows a shift from terrestrial to marine diet during this period (data from Dansgaard et al. 1975 Arneborg et al. 1999)... 

Figure 8 Archaeological glass, medieval, with enamel-like surface layer, an overview...

Degradation processes in medieval stained glass windows have been studied using FT-IR spectroscopy and the pigments applied to early specimens have been characterized using the FT-Raman technique. Similar methods have been used to study early enamels and cloisonne specimens. 

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