The Story of the Westland Cauldrons in Europe
Authors: Bollingberg Haldis Johanne , Hansen Ulla Lund 
Published: December 2016

When examining the importance of the distribution of trace elements in metal objects, for example that a Scandinavian analytical project on 500 metal artefacts from the Roman Iron Age has shown that the relationship between selected trace elements are characteristic of the different groups of artefacts - they might even be typical of different Eggers types within the same group. For instance, a ladle/strainer set from the Late Roman Iron Age (LRI), E 161, may have a significantly higher lead/antimony ratio than the older types, E 162. The verification of this principle has, firstly, shown that the scrap metal content of an artefact alloy affects the interpretation of chemical analyses much less than has hitherto been supposed. Secondly, it has shown that elemental alloy composition for the artefacts are more closely related to the raw materials. For example, the ores used have a characteristic content that is a consequence of their geochemistry. While there are always small amounts of silver, antimony and bismuth in galena, the amounts are a function of the location and geological formation of the ore. These facts are well recognized in lead isotope research where the ratio between the lead isotopes is used.

The results from the interdisciplinary analytical projects mentioned above are the basis for a continuing examination of relevant artefacts from Nordic and European collections. Initially it was not expected that permission to collect foreign collections would be granted but, in the event, personal contact and a careful sampling protocol opened the doors to international cooperation. Comparative projects are currently proceeding with the Vatican Museum, the Musée Royaux d’Art et d’Histoire, Brussels and Römisch-Germanisches Zentralmuseum, Mainz and Goethe University, Frankfurt a. Main among others. Glass and metal samples from the excavation of Corway Kloster have been analysed by OES in cooperation with German Universities, with fi nancial support from Volkswagenstiftung over many years. Finally, it is important that all kind of treatment of the artefacts during the study is described in detail and following the artefacts for later scientific work.

Elemental analyses are a fingerprint of the alloy content. It has been possible to distinguish the various cauldron alloys from the Roman and the Migration Period. The composition of the alloy characterizes the Westland cauldron compared to other artefacts from the Roman period. The similarity between the alloy in the Scandinavian and some French and Belgian Westland cauldrons is documented, which could point to a common provenance. The alloy composition changes according to form and age. The trace element pattern and the lead isotope relations point to an origin in the Maas valley. The use of scrap metal in the alloy seems avoided for the body of the cauldrons - probably because of the complicated production of the thin walls and bottoms of the cauldrons. In conclusion, one can say that detailed studies of the alloys the ancient smiths have used are providing new knowledge of the expertise and cultural achievements of former ages. One can also assert that the chemical and metallurgical constitution of archaeological treasures is as important as their stylistic description in revealing important aspects of our cultural history.