WET ARCHAEOLOGICAL WOOD: CHEMICAL STUDY OF DEGRADATION AND EVALUATION OF CONSOLIDATION TREATMENTS

The present work describes a thoroughly analytical study of the chemical changes produced in waterlogged woods collected from different different archaeological sites. This study is very important in order to develop appropriate measures for the conservation of historical wooden artifacts. The chemical changes produced in the waterlogged woods were studied by different pyrolytic techniques: direct exposure electron ionization-mass spectrometry (DE-MS), pyrolysis coupled with gas chromatography-mass spectrometry (Py-GC/MS) and Py-GC/MS in the presence of hexamethyldisilazane (HMDS) as a derivatising agent. The study concluded that the main structural changes occurring in waterlogged woods are the removal of carbohydrates. The lignin moiety remains largely unaltered, although some small changes could also be observed, such as depolymerisation, demethylation of methoxyl groups and some evidences of a slight oxidation of α-carbon of the lignin side-chain. In the last chapter, the author also describes the morphology of degraded archaeological waterlogged woods and the evolution of penetration of different wood impregnants by the use of X-ray synchrotron radiation microtomopraphy (SR-μCT), which gives useful insights into the use of different consolidation treatments.