The use of Hand-Held XRF for investigating the composition and corrosion of Roman copper-alloyed artefacts

Abstract

The study of archaeological artefacts using deployed in situ analytical instruments presents some obvious advantages. Including, obtaining an immediate feedback that can be used to redefine in real-time fieldwork strategies. Ideally analytical field instruments should also have characteristics that limit damage to the studied artefact.Here, we present a case study on the use of a Hand Held XRF (HH XRF) device employed to define the composition of copper-alloyed artefacts retrieved from the Roman military site of Fectio in the vicinity of Vechten (The Netherlands). The goals of the study were to establish artefact preservation status, to investigate artefact elemental composition, and to compare the composition of artefact corrosion layer and uncorroded core. The results showed that the objects were in an overall good preservation state. Decuprification and dezincification represented the probable main corrosion processes resulting in the formation of smooth corrosion layers or patinas. The major elemental composition of the artefacts' uncorroded cores showed a wide-range variability most likely associated with recycling practices of scrap metal during the 3 rd century CE.

Portable XRF on Prehistoric Bronze Artefacts: Limitations and Use for the Detection of Bronze Age Metal Workshops

“…The curve depicting element distribution for the neck collar from Luttmissen, in Lower Saxony2, for example, showed a rapid drop of the copper values, as well as a simultaneous and disproportionate increase in tin content with the transition to the corrosion layer (figure 1). Similar phenomena have already been documented in other studies of ancient bronzes, mostly within conservation studies, while comparable results have been achieved in studies of artificially-created patinas (Fernandes et al 2013, 5, Oudbashi et al 2013, 3, Šatović et al 2013, Constantinides et al 2002. Copper dissolution, which starts with selective dissolution from the copper solid solution α-phase (see Robbiola et al 1998Robbiola et al , 2108, is commonly known as 'decuprification'.…”

“…In the first case, the results of these analyses can determine the morphology of corrosion crusts (see also results by Constantinides et al 2002, Fernandes et al 2013, Mircea et al 2012, Wadsak et al 2000. When considered alongside other factors (e.g.…”

“…As comparative studies have shown, bronzes with 'noble patina' (type I patina) and a high lead content might be better suited for such investigations (e.g. Fernandes et al 2013Fernandes et al , Šatović et al 2013. Table 2.…”

“…The metals contained in the immediate area around the deposited bronzes can accumulate in the corrosion, in particular manganese and cobalt, as well as phosphorus and silicon, which appear frequently in modern soil due to the effects of modern agricultural work. Thus, it can create a concentration of secondary metals, including iron (Fernandes et al 2013, 4, Pernicka 1995 and aluminum (Mircea et al 2012, 183). Robbiola and colleagues (1998), as well as Chase (1994), have suggested that ion migration is responsible for the observed effects within the corrosion layer.…”

“…Several studies have concentrated on the analysis of corrosive structures on copper alloy objects (e.g. Bernard & Joiret 2009, Chase 1994, Constantinides, Adrianes, & Adams 2002, Mircea, Sandu, Vasilache, & Sandu 2012, Oudbashi, Emami, Ahmadi, & Davami 2013, Robbiola, Blengino, & Fiaud 1998, Wadsak et al 2000, while only a small number have discussed the analysis of corroded artefacts using handheld XRF devices (Fernandes, van Os, & Huisman 2013, Šatović, Desnica, & Fazinić 2013. Unfortunately, these studies are typically published within the domain of conservation studies and seldom find their way to archaeologists.…”