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The analyses to determine the state of preservation of waterlogged archaeological wood follow three different directions: anatomical analyses, physical evaluation and chemical characterisation. Physical parameters (densities and moisture content) are the ones most frequently found in the specialised literature. The measurement of moisture content is normally referred as maximum water content (MWC) in the case of archaeological wood in waterlogged conditions, because wood has been long-time preserved by the lack of oxygen in waterlogged conditions. Aim of the paper is the comparison of three pre-measurement treatments in the calculations of MWC: without any vacuum-pressure treatment, after 300 mbar vacuum pressure and after 50 mbar impregnation in water. The evaluations were performed on 240 samples of waterlogged archaeological wood coming from different excavation sites and including different wood species (both hardwoods and softwoods) in different state of preservation, from low to very high decay. The three tested methodologies to measure the maximum water content on waterlogged archaeological wood provided substantially equivalent results. Nevertheless, a deeper analysis of the results showed that the MWC values of 300 mbar impregnations were rather low compared to MWC standard measurements. Thus, this impregnation was a little bit harsher, causing most probably an anatomical damage on a portion of most degraded samples. The opposite result was obtained after the 50 mbar impregnation procedure. In this case, the MWC values were slightly higher. This means that this treatment seemed to be more effective in subtracting even the smallest air bubbles trapped inside waterlogged archaeological wood samples. Some suggestions on how to measure MWC on waterlogged archaeological wood are detailed at the end of conclusions. [ABSTRACT FROM AUTHOR]

Abstract: Artefacts made of wood coming from archaeological excavations provide insights into human cultural behaviour of the past. They show how man utilised natural resources and how the development of woodworking techniques and artistic endeavour were developed. Within archaeological contexts, waterlogged anaerobic conditions generally preserve the appearance of artefacts, although wood is subject to severe decay processes. The said conditions can transform the original material into a new one, thus demonstrating specific differences from those of the “fresh” wood of the same species. In order to assess these new properties correctly, an integrated diagnostic approach is needed, one which includes a multidisciplinary (micromorphological, physical and chemical) evaluation of the state of preservation. This paper reports several diagnostic results regarding wood artefacts coming from a series of archaeological excavations carried out in Italy. Different types of artefacts – ships, furniture, foundation piles, etc. – that date to different eras (Roman times, the Middle Ages, the Renaissance) have been included in this study. In addition, several species of wood at different levels of decay were analysed. Our study provides evidence of how a multidisciplinary approach, based on anatomical (micromorphological), physical and chemical analyses, avoids goes beyond the limits of each single type of analysis, thus contributing to a complete and reliable evaluation of the state of preservation of these archaeological artefacts. [Copyright &y& Elsevier]

Abstract: This paper deals with the diagnostic analysis performed on the different timber structures of the Nativity Church. The surveys were performed in agreement with the Italian standards UNI 11161:2007 and 11119:2004. The uniqueness of some structures made it necessary also the analysis and description of structural typologies. The results allow describing the different timbers utilised, the state of preservation, mechanical and biotic decays and finally to determine the present strength of each wooden element, obtained through the combination of the evaluation of the defectiveness and the measurement of the residual sections. The results of the diagnostic survey will influence the design of the structural restoration and of the maintenance operations. [Copyright &y& Elsevier]