Chloride ions are an important actor in the corrosion of iron-based archaeological artifact. To stop this degradation, excavated objects are subjected to dechlorination treatment. However, there is no guarantee that this will remove all chloride from the object, as some can be found deep inside the object. To assess the ability of dechlorination treatment to remove chloride, we propose to use both neutron and X-ray tomography. Indeed, these tomographic techniques have sensitivities to different elements and are thus complementary. Neutron tomography in particular is highly sensitive to the presence of chloride. This study demonstrate that this methodology allows to detect local and global changes caused by the dechlorination treatment, an useful tool to assess the effectiveness of a treatment and potentially improve it.

International audienceThemed issue: Synchrotron radiation and neutrons in art and archaeology 2014 PAPER Claire Gervais et al. Degradation mechanisms of reinforcing iron rebars in monuments: the role of multiscale porosity in the formation of corrosion products investigated by X-ray tomography Monuments in stone often contain metallic reinforcements, the stability and degradation state of which determines the entire integrity of the edifice. Understanding their long-term corrosion process is thus an essential step towards a safe and efficient conservation strategy. In this study, we show that combining laboratory and synchrotron tomography at different scales is efficient for getting an overall three-dimensional picture of the iron corrosion products found in iron rebars from Orí eans cathedral. We demonstrate that beside chemical characterization of the corrosion products, the study of the shape of the corrosion products, their spatial distribution within the stone binder and their relationship with the porosity of the binder can bring significant insights into the corrosion process, and particularly help in understanding the multiple roles that porosity plays in corrosion

This research project examines the effects of X-rays on cellulose and some moulds frequently found on paper. The aim was to identify applications for X-ray irradiation that can be used as a disinfection method for archival material. The question was if X-rays are suitable as an alternative to gamma radiation and if they are less harmful. For this purpose, the minimum X-ray dose required to reduce the microbial count to a harmless level was determined. The material-altering effect was examined on samples treated with X-rays and gamma radiation. Spectrophotometric measurements showed that there is no noticeable colour change with either type of radiation. The determination of the molecular weight distribution, in turn, showed that the molar mass of the cellulose is considerably reduced with both treatment methods. Using mechanical tests, however, it could be demonstrated that this has no significant influence on the tensile strength. The examination of the oxidation behaviour also showed no significant difference between the differently treated samples. The studies demonstrated that both methods have an almost identical effect on cellulose. Thus, X-ray treatment is primarily a supplement to the known disinfection methods and is particularly suitable for objects that would not withstand treatment with alcohol.