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L’etude de l’alteration des marqueteries metalliques du mobilier Boulle a ete menee en 2010 au C2RMF, prealablement a la restauration de trois meubles du musee du Louvre. Elle a permis de preciser les types d’alteration des elements en laiton et en etain en fonction de leur composition, de leur corrosion, des contraintes mecaniques et des restaurations anterieures. Le ternissement du laiton est le resultat des processus d’oxydation (cuprite) et de dezincification (zincite, couche de cuivre metallique), avec souvent presence d’atacamite. Le ternissement de l’etain correspond a la presence de cassiterite (SnO2). L’etain Boulle est un alliage specifique etain-plomb-mercure utilise pour l’obtention d’un effet miroir. L’ajout du mercure rend l’etain plus dur mais plus fragile ; le phenomene de craquelure qui en resulte est egalement decrit dans cet article.

Bertholon Régis. Soustractions et conservation. De l’intérêt de la conservation-restauration dans l’étude archéologique des objets. In: Histoire de l'art, N°32, 1995. De la restauration à l’histoire de l'art. pp. 85-91.

A new application of electrolysis for the dechlorination of copper alloys has been developed. Electrolytic treatment with weak polarization in sodium sesquicarbonate permits the extraction of the chlorides and the preservation of the stable alteration products. It is more effective and less time-consuming than chemical methods. The method has been applied successfully to archaeological objects from both marine and land sites.

Publisher Summary This chapter highlights that archaeological metal objects have a dual status; they are both the valuable remains of cultures from the past and the samples of corroded materials. As a part of our cultural heritage, they constitute our main information source regarding ancient metallurgy and the corrosion behavior of metals buried for centuries. Most often, they cannot be studied right after their excavation because of their dramatic alteration during burial. Conservation aims to take care of these pieces of our heritage to allow both archaeological studies and public display. Therefore, conservation and restoration treatments have to reveal the artefacts' characters, such as shape, decoration and surface details, fabrication, use, etc. Of great importance for these purposes is to locate the original surface before corrosion. The chapter presents an overall view of some issues related to conservation and location of the original surface of archaeological metal artefacts. It also highlights some concepts to build a framework of research on these issues.

Une nouvelle application de l'electrolyse a la dechloruration des alliages cuivreux a ete mise au point. Le traitement electrolytique a faible polarisation dans le sesquicarbonate de sodium permet l'extraction des chlorures et la conservation des produits d'alteration stables. Son efficacite est superieure a celle des methodes chimiques et sa duree est moins importante. La methode a ete appliquee avec succes a des objets archeologiques provenant de milieux marins et terrestres

Bertholon Régis, Lacoudre Noël. Le traitement par électrolyse des outils en fer découverts à Jerash . In: Syria. Tome 66 fascicule 1-4, 1989. pp. 169-175.

This paper presents the outcomes of the CANS project (Conservation of cAns in collectioNS), an interdisciplinary research aiming at proposing conservation strategies for full cans, still retaining their original contents, in museums and collections. The paper includes the results of the condition report, measuring the state of conservation of 150 cans from 5 Swiss collections, the correlation between state of conservation, content and age of the can and the extensive characterization of the cans’ materials for a better understanding of the corrosion mechanisms.

The description and identification of corrosion products formed on archaeological iron artefacts need various approaches at different observation scales. For this study, samples from five sites were prepared using two techniques. The first consists in cutting cross-sections perpendicular to corrosion layers. This allows local observations and analysis of the corrosion layer stratigraphy at different levels. The second consists in performing manual grinding or abrading of the corrosion layers starting from the current surface of the excavated artefact to the metal core. It allows the description of the successive layers and is well adapted for the analysis on a larger scale. In addition to these two observation scales, the identification of the iron oxides formed needs the coupling of several complementary techniques. Elementary compositions were determined by scanning electron microscopy–energy-dispersive x-ray (SEM–EDX) analysis and electron probe microanalysis (EPMA). Structural identification was performed by x-ray micro-diffraction under synchrotron radiation (µXRD) and micro-Raman spectroscopy. These analyses were performed on the same samples with both x-ray diffraction and Raman spectroscopy in order to ensure a reliable characterization. In some cases there are some ambiguities or overlapping between signatures of different phases by µXRD (such as maghaemite–magnetite) or Raman spectroscopy (such as goethite–magnetite) which can be overcome by the association of the two methods. The final aim is to set up an analytical methodology that will be optimal for the study of ancient iron corrosion products. It is the first step in the study of long-term mechanisms of iron in soil. Copyright © 2004 John Wiley & Sons, Ltd.