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Methods of fabrication
Published in R. F. Tylecote, The Prehistory of Metallurgy in the British Isles, 2017
Depletion gilding and silvering can be used where the matrix contains enough noble metal to provide a coating when the base metal is removed by oxidation and leaching. But recent work on Peruvian copperbase alloys has clarified the mechanism of electrochemical replacement gilding.184 Very thin gold layers (1μm) were obtained by immersion in a warm aqueous solution containing an 85%Au-15%Ag alloy. The solution contains NaCl, KN03, and alum and it is clear that local cells are set up, with the small areas of Cu-alloy acting as the anode and the majority as the cathode where there is deposited a thin layer of Au-Ag alloy. The active constituent is probably AuCl3. It would seem that this is the mechanism by which tin is plated onto brass pins. Naturally the tin must be cathodic to the brass.
Metals, Minds and Mobility: Integrating Scientific Data with Archaeological Theory
Published in Ambix, 2019
The dialogue among the chapters within each part, however, is not always convincing. The first part opens with Tobias L. Kienlin’s theoretical chapter on knowledge transmission. While emphasising the importance of a link between archaeological science and historical theory to interpret the technological development of prehistoric Europe, he voices scepticism about the most recent world-systems theory as an interpretative framework. This theory is based on the distinction between a centre that gives rise to technological and cultural innovation as well as elite objects, and a culturally receptive periphery that provides raw materials in exchange for objects. Kienlin challenges the idea of the prehistoric Eastern Mediterranean as a centre and continental Europe as an under-developed hinterland, claiming that the theory does not sufficiently engage with how new materials and technologies from the East were reinterpreted by European societies. This critical view does not sit well with the claims of the third chapter, by Catalin Lazar et al. It deals with the circulation of metals at the dawn of metallurgy in Romania, highlighting differences between the majority of sites where only few metal artefacts have been found, and the case of Pietrele, where hundreds of metal artefacts were recorded. The authors hypothesise that the difference is due to the emergence of elites who controlled the new material and its distribution. This model of circulation around an elite centre is not well supported by data, and is in direct contrast with Kienlin’s theoretical deliberations. The fourth chapter, by Alicia Perea, hardly engages with the theme of transmission; it discusses how complex metal production is embodied in the ritual framework of ancient societies, using two very different contexts as case studies: the lost-wax technology combined with surface depletion gilding used by the Quimbaya group in Colombia to produce statues embodying ancestors, and a complex procedure to fragment gold bracelets used in the Atlantic Late Bronze Age. The fifth chapter, by Bianka Nessel et al., deals with the tin-bronze metallurgy in Mesopotamia, Anatolia, and parts of Europe, focusing on the use of tin isotopes to approach the well-known problem of provenancing tin. Although the overlapping results make it hard to identify the source of tin for individual objects, and therefore to discuss the transmission of technologies, the general overview shows social factors in the distribution of tin in Mesopotamia and Europe.