The core idea of this project has been in development for a very long time – by now, it must be over 10 years. While writing my PhD about European Bronze Age swords I came across the article of McKerrell – Tylecote 1972 and became curious about the amount of arsenic that actually remains in bronze after several (prehistoric) recycling processes. I tried to find further literature focusing on this but apart from the article of Lechtman 1996, the unpublished PhD-thesis and some hard-to-get articles of Paul Budd, as well as the article of Northover 1989, not much seemed to have been done until around 2005.
In the meantime I focused on other topics: I finished my PhD, documented Bronze Age weapons and tools in the Baltic States, then moved to Carinthia and started to work at the local Landesmuseum. Amongst other things, research projects of the Austrian FWF, CHARISMA and Marie Skłodowska-Curie actions subsequently permitted me to study and analyse e. g. European Bronze Age body armour at the Laboratorio di Metallurgia e Materiali in Genoa.
However, I remained intrigued by the loss of arsenic during prehistoric smelting and melting. Every time I saw diagrams in archaeological publications linking the amounts of As, Sb, Ni and Ag together in order to locate geographically a copper mine, I had the Ellingham diagram of the formation of common metal oxides in mind, noting that arsenic (as well as Sb) is far from being as stable as these publications sometimes would lead one to believe.
A literature study at the end of 2014 indicated that even up until that point, no further experiments had been published. However, recent studies carried out by M. Pollard, P. Bray and A. Cuenod demonstrate the importance of arsenic as a marker for the intensity and / or number of recycling activities in the Bronze Age, and how it may indicate direct or indirect connections between the owner of the final object and the mine(s) where the copper was originally produced. In addition, thermodynamic studies on CuAs are now close to being published (B. Sabatini).
Starting with a project to investigate the construction of out-of-equilibrium phase diagrams of Cu-As, to evaluate mechanical properties and characteristics of arsenical bronzes and finally, to quantify and evaluate the loss of arsenic as it occurred during prehistoric manufacturing processes, will certainly be a challenge – scientifically as well as for health reasons, since arsenic is not really famous for its positive effects on one’s health.
Ultimately though, I am thrilled that from July 2015 on I can finally start to work with arsenical bronze after all these years – and especially to have the opportunity to carry out this project at the IRAMAT-CRP2A at Bordeaux in cooperation with the LMM at Genova!