The conservation of metallic archaeological and historic artefacts is a major challenge whether they are ancient bronzes or relics of our more recent industrial past. Based on the work of Working Party 21 Corrosion of Archaeological and Historical Artefacts within the European Federation of Corrosion (EFC), this important book summarises key recent research on analytical techniques, understanding corrosion processes and preventing the corrosion of cultural heritage metallic artefacts. After an introductory part on some of the key issues in this area, part two reviews the range of analytical techniques for measuring and analysing corrosion processes, including time resolved spectroelectrochemistry, voltammetry and laser induced breakdown spectroscopy. Part three reviews different types of corrosion processes for a range of artefacts, whilst part four discusses on-site monitoring techniques. The final part of the book summaries a range of conservation techniques and strategies to conserve cultural heritage metallic artefacts. Corrosion and conservation of cultural heritage metallic artefacts is an important reference for all those involved in archaeology and conservation, including governments, museums as well as those undertaking research in archaeology and corrosion science.

This chapter deals with the description of suitable and innovative solutions devoted to preserve metallic artefacts in their original contexts, underwater cultural heritage sites of archaeological and historical interest, as well as with the analysis of the degradation processes of ferrous and non-ferrous artefacts induced by contact with an aggressive environment such as sea water. The chapter also provides an overview of the most common conservation strategies applied to recovered artefacts.

The conservation of metallic archaeological and historic artefacts is a major challenge whether they are ancient bronzes or relics of our more recent industrial past. Based on the work of Working Party 21 Corrosion of Archaeological and Historical Artefacts within the European Federation of Corrosion (EFC), this important book summarises key recent research on analytical techniques, understanding corrosion processes and preventing the corrosion of cultural heritage metallic artefacts.After an introductory part on some of the key issues in this area, part two reviews the range of analytical techniques for measuring and analysing corrosion processes, including time resolved spectroelectrochemistry, voltammetry and laser induced breakdown spectroscopy. Part three reviews different types of corrosion processes for a range of artefacts, whilst part four discusses on-site monitoring techniques. The final part of the book summaries a range of conservation techniques and strategies to conserve cultural heritage metallic artefacts.Corrosion and conservation of cultural heritage metallic artefacts is an important reference for all those involved in archaeology and conservation, including governments, museums as well as those undertaking research in archaeology and corrosion science. - Summarises key research on analytical techniques for measuring and analysing corrosion processes - Provides detailed understanding of corrosion processes and corrosion prevention - Discusses on-site monitoring techniques

In the present chapter laser-induced breakdown spectroscopy (LIBS) is introduced as a powerful spectrochemical analytical technique that can be exploited to characterize corroded artifacts. Scientific and technological aspects of LIBS are briefly presented. LIBS does not need sample preparation, it is nondestructive and it can be used for in-situ measurements. Examples of LIBS applications that can help archaeologists in conservation and restoration of metallic artifacts are given. We demonstrated the use of LIBS in analysis of corroded metal threads, depth profiling of copper-based decorative artefact, analysis of corroded Punic coins, and LIBS and XRF analysis of Roman silver denarii.

This chapter discusses the importance of using standards in conservation methodology and practice for cultural heritage (CH) metals. The past general trend in the field is the use of metal industry standards. The chapter surveys the relevant scientific publications, and concludes that conservation researchers use a variety of these standards adopted by different organisations. As a result, it can be difficult to compare scientific data for CH metal studies carried out by different laboratories. The chapter discusses the necessity to draft new standards for metals specific for CH by examining how three independent researchers had different findings when testing the same coating. The role of CEN/TC 346 ‘Conservation of Cultural Heritage’ is also discussed.

The use of silver in ancient civilisations of Mesopotamia, Egypt, Ionia, Greece, Rome and China is presented. Principles of silver corrosion in different environments containing humidity, oxygen, carbonates, sulphur, chlorides, peroxides, ozone and UV, and the morphology of the corrosion layers are described. Cleaning, anti-tarnishing and protection methods are explained. Inhibitor hexadecanethiol (HDT) and a composite coating of Paraloid B-72 containing 2% nano-alumina pigment are tested on silver specimens with tarnished and corroded surfaces and found to be protective when exposed in sulphides and chloride environments in the laboratory, satisfying aesthetic and reversibility criteria.

‘Artistic/intentional’ patina is a surface layer intentionally produced by an artist or a specialized professional on a metallic artwork with aesthetic or practical purposes. From the science of surfaces point of view the ‘artistic’ patina could be considered as an interface between the metallic substrate and the external environment and therefore affecting, depending on its physical and chemical peculiarities, the corrosion process. In order to understand how the ‘artistic’ patina behaves inside the exposure environment, an experimental activity was carried out: the study of the data collected with the application of different analytical techniques contributed to a more pertinent knowledge of the characteristics of metallic works of art which, in turn, leads to a restoration process respecting their real nature.

The authors consider the case of iron atmospheric corrosion to illustrate the possibility of developing a conservation diagnosis for a given material in a given environment. In the particular case of iron atmospheric corrosion, samples from the site of the Amiens Cathedral in the North of France have been characterised in order to identify the different phases constituting the corrosion product layers. The layers consist of a matrix of iron oxy-hydroxide goethite embedded with several ferrihydrite marblings. Other phases such as as lepidocrocite, maghemite and akaganeite are present in minor quantities. A degradation index is first defined from the phase proportions and from the intrinsic electrochemical properties of those phases. Further, the electrochemical reactivity of scratched rust powders has been studied to define a second degradation index. From these two degradation indices a first step towards a corrosion diagnosis method is proposed.

This chapter reviews the applicability and specific uses of corrosion inhibitors in metal conservation practice. Corrosion inhibitors are one of the different methods used by conservation-restoration professionals to preserve metallic cultural heritage. In the first part, specific requirements and needs for corrosion inhibitors in conservation treatments are reviewed, as well as the different methods for the assessment of their efficiency. The second part of the chapter reviews the different inhibitors used by type of metals: copper and its alloys, iron and its alloys, and other metals (including silver, lead and zinc), from traditional ones to state-of-the-art treatments.

This chapter introduces the techniques used when investigating corrosion layers formed on cultural heritage artefacts. Various multiscale analysis methods, from macroscopic to nanoscopic scales, are presented. Information on the morphology, the elementary composition and the crystalline structure that each method allows for determining the constituents of the corrosion layers is examined, as well as their limits in terms of set-up, spatial and detection resolution. This chapter discusses the characteristics of the scientific tools that can be used to understand corrosion phenomena, by taking into account the major parameters responsible for alteration mechanisms.