Chemical Analyses of Ancient Ceramics: What for?

Abstract

Several examples of the use of chemical methods to solve questions such as the effects of soil contamination, the use, the provenance, and the manufacturing of clay-based ceramics are presented. As illustrated by the element phosphorus, it is possible for chemical components to migrate into and out of a broken pot during the burial stage. The analysis of food residues, such as crusts on or organic substances in the ceramic piece shows that the medieval population in England ate mainly cabbage, whereas the Indians of Manitoba (Canada) relied on a diet of fish and animal fats during the 10th–16th centuries. The chemical analysis of the unusually large bricks produced by Cistercian monks in Switzerland during the 13th century gives evidence of the existence of other manufacturing places, such as Fraubrunnen and Frienisberg, in addition to the main factory located at the monastery of St. Urban. Some 18th to 19th century Swiss fayences from the Matzendorf and Kilchberg-Schooren production sites are not easy to attribute to a specific center based on stylistic arguments alone, but they can be clearly differentiated in their chemical composition. Furthermore, scientific evidence suggests that artisans moved from Kilchberg-Schooren to Matzendorf, and vice versa. As exemplified by the so-called 'glossy clay layer', surprising results show that not only the mineralogical and chemical composition of the clay layer, but also the CaO content of the ceramic body, has a significant influence on the gloss – a fact that was well known to ancient Roman potters.