Conservation and Archaeological Science for the Protection and Understanding of Ancient Craftsmanship in Cultural Heritage

Methodologies for the investigation of corroded iron objects: examples from prehistoric sites in South-eastern Arabia and Western Iran

“…This may be due to either the limited production of such steels during the early Iron Age or, more likely, by the analogy with low-carbon RSs, due to the analyti-cal challenges of recognizing thin (or absent) networks of hypereutectoid cementite (Figure 6(b)). Although optical microscopy can be used for identifying RSs of close-to-eutectoid composition, backscattered electron imaging allows for better recognition due to a greater contrast between residual cementite (or pearlite) and the corroded iron oxide matrix, as shown in former studies (Notis 2002;Golfomitsou et al 2017) and confirmed by the present investigation.…”

“…This observation was made as early as the 1960s (Knox 1963) and several subsequent works have utilized this characteristic of iron corrosion to identify RSs in archaeological ferrous specimens (e.g. Agrawal et al 1990;Golfomitsou et al 2017;Notis 2002;Tholander 1971;Scott 1976Scott , 1989. However, probably because of the complex and highly variable nature of the corrosion process, the majority of these studies aim only at general characterization of RS (Knox 1963;Scott 1976;Golfomitsou et al 2017), focus on analytical techniques (Notis 2002), or in attempt to explain preservation of RSs propose complex theories not backed by robust scientific evidence (Scott 1989, 13).…”

“…Agrawal et al 1990;Golfomitsou et al 2017;Notis 2002;Tholander 1971;Scott 1976Scott , 1989. However, probably because of the complex and highly variable nature of the corrosion process, the majority of these studies aim only at general characterization of RS (Knox 1963;Scott 1976;Golfomitsou et al 2017), focus on analytical techniques (Notis 2002), or in attempt to explain preservation of RSs propose complex theories not backed by robust scientific evidence (Scott 1989, 13). The present study, therefore, aims to contribute to the debates on this subject, discussing mechanisms of formation of RSs based on the observations obtained from the investigation of corroded ferrous objects originating from different burial environments.…”

“…Despite the impossibility of fully reconstructing the metallographic structure of this corroded sample (as only 10-20% of RSs are preserved), it is possible to successfully assess the carbon content of a variety of components that are important from the practical perspective, such as cutting edges, justifying the use of invasive study (cf. Golfomitsou et al 2017). However, the objective assessment of carbon content in samples of a small size (and hence more vulnerable to corrosion), and which originate from a highly aggressive burial environment (such as in South-eastern Arabia), represents a significant challenge, due to the lower proportion of preserved remnant areas (5-10% in the samples that are less than 7 mm in thickness).…”