The role of surface analysis in the strategies for conservation of metallic artefacts from the Mediterranean Basin

Abstract

Conservation and valorization of cultural heritage is a fundamental element and an essential mission of the Mediterranean countries where most of the ancient and fascinating witnesses of human art and creativity are conserved. A large component of this cultural heritage consists of material cultural assets that are often exposed to harmful long‐term effects of environmental pollution, inappropriate handling, and intrinsic chemical–physical instability. Many risks can be mitigated, provided that there is a proper knowledge of the materials involved and of their degradation processes and adequate means to counteract these processes or to restore the materials. The employment of surface analysis can be extremely useful for the development of both tailored conservation procedures and methodologies as a function of the different degradation mechanisms that affect the artefacts, as well as for the monitoring of the conservation state and the identification of the manufacturing techniques. Several metallic artefacts coming from different archaeological sites of the Mediterranean Basin have been examined: weapons found during the excavation of the Ayanis fortress of the Urartu civilization (Lake Van, Anatolia, Turkey) and silver and bronze artefacts found at Tharros (Italy), a Phoenician–Carthaginian and then Roman city located along the Sardinian coast. They have been studied by means of the combined use of selected area X‐ray photoelectron spectroscopy, X‐ray diffraction, optical microscopy, and scanning electron microscopy + energy dispersive spectrometry. The surface analysis techniques are able to give important contributions in the identification of chloride ions that may dramatically affect the chemical–physical stability of the copper‐based artefacts, thus allowing developing proper conservation strategies, as well as in the identification of the presence of mercury on gilded artefacts, thus giving information on the manufacturing technique. Copyright © 2014 John Wiley & Sons, Ltd.

Reproducing bronze archaeological patinas through intentional burial: A comparison between short- and long-term interactions with soil

“…Due to the proximity to the sea, archaeological finds, especially metal objects, show very bad conservation conditions [ 36 , 37 ]. As evidenced by chemical analysis conducted on the Tharros’ soil in the framework of the European Project EFESTUS (INCOME contract n° ICA3-CT-2002-10030) [ 38 ], large amounts of chlorine and smaller amounts of phosphorus are present in the soil.…”

The Fontanamare Discovery (Sardinia Coast, Italy), a Case of Underwater Corrosion of Bronze Coins

“…In this paper, nine bronze coins from the Fontanamare wreck, selected on the basis of the nature of patinas, were investigated for the first time, using a multi-analytical approach combining optical microscopy (OM), micro-Raman (µ-Raman) spectroscopy, and X-ray diffractometry (XRD) to analyze the nature of the patina. Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM and EDS) was used to study the microstructure of corrosion products and the nature of alloys by analyzing the surface and cross-section [4].…”

Study on a silver box unearthed from the Tang Dynasty (AD 618–907) tomb at Xiaolizhuang Site, Henan Province, China

“…Numerous studies of ancient silver artifacts were reported in scientific literatures. The main areas of research are the investigation of provenance [3][4][5], chemical composition and microstructure [6][7][8][9][10] and manufacturing processes [1,[11][12][13]. In ancient China, the sophistication and the technical skills in metalworking of gold and silver artifacts reached its peak in the Tang Dynasty.…”

“…Apart from the written source, numerous silver artifacts were excavated from tombs of the Tang Dynasty over the years. Some limited studies with focusing on the surface design [19][20][21][22][23][24][25] and chemical composition [6] were performed, however, the surface features and manufacturing marks that essential for understanding the metalworking techniques [13] were often overlooked. Tan's team has done a great job on studying the silver artifacts from the Wei family tomb of the Tang Dynasty [26].…”