Evaluation of Conservation Treatments for Archaeological Waterlogged Wooden Artefacts

In favourable conditions of low temperature and low oxygen concentration, waterlogged wooden artefacts, such as shipwrecks, can survive underwater in relative good condition. Nevertheless, as a result of the action of water and anaerobic bacteria on the cellulose and hemicellulose of the cell walls, the waterlogged wood is very fragile and its consolidation is necessary. These conservation treatments are very often expensive and technically difficult, as they involve the replacement of the waterlogging water with the consolidants, filling the cell walls and all cavities in order to prevent stresses during the drying. Since the effectiveness of the treatment strongly depends on its distribution, the penetration depth and the degree of cavities-filling have been evaluated by micro x-ray tomography (µ-CT). Both laboratory and Synchrotron Radiation-based µ-CT experiments have been performed on different samples coming from findings excavated in the San Rossore archaeological site (Italy), in order to study in detail how the different application parameters can influence the manner in which the conservation products fill the cavities of the wooden structure (i.e. complete or partial volume filling, complete or partial impregnation of the wooden artefact).