Acetylated wood (WAc) shows improved properties largely due to the reduced amount of water in its cell wall, but the exact mechanism of water reduction remains unclear. Acetylation reduces hydroxyl (OH) content by acetyl (Ac) substitution but may also limit water access to unmodified OH groups by steric hindrance. In the present work, the accessibility of OH groups in acetylated or propionylated Radiata pine (Pinus radiataD. Don) wood (WAcand WPr) was investigated by deuterium exchange, saponification in sodium hydroxide followed by high-performance liquid chromatography (HPLC) analysis and weight percentage gain determination of the modified samples. Acetylation reduced OH accessibility (OHA) to a greater extent than would be predicted, if OH substitution were the only responsible mechanism for accessibility reduction. The combination of deuterium exchange and saponification results provides strong evidence that steric hindrance plays a key role in reduction of water accessibility to unmodified OH groups in WAc. The supramolecular architecture of WPrsamples seems to be modified by the propionylation reaction, which leads to increased OHAat low levels of substitution. This suggests that molecular restructuring within the cell wall exposes new OH groups after propionylation. At higher levels of substitution, however, the WPrexhibited less OHAthan expected indicating steric hindrance from the propionyl groups.

The aim of this research is to determine if the polyesterification of sorbitol and citric acid in wood has a future potential as a wood modification process. Pine wood was impregnated with an aqueous solution containing citric acid and sorbitol and was thereafter cured at 103 or 140°C for 18 hours. The dimensional stability and leaching resistance were studied for both modification temperatures. The leachates from the modified wood samples were analysed by HPLC and the susceptibility to decay and staining fungi were studied. Impregnated samples cured at 140°C showed a permanent (leach-resistant) increased dimensional change, but samples treated at 103°C were not stable to leaching. Treated samples cured at 103 and 140°C showed significant resistance to white-rot (Trametes versicolor) and brown-rot decay (Postia placenta) after a leaching procedure. Furthermore, samples cured at 103 and 140°C (leached and unleached) were significantly less susceptible to blue-stain fungi than the untreated controls.

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Due to problems with most of the existing conservation treatments, new materials for the stabilization of waterlogged archaeological wood are highly desirable. The ideal consolidant should be environmentally friendly and safe to work with for conservators, while strengthening the objects without ruining the visual impression of the wood or filling it in ways that prevent re-treatment in the future. This paper tests chitosan since it is a multifunctional material that not only offers support but also hinders catalytic activity by potentially chelating reactive metal ions. Three solutions of % chitosan in . M acetic acid were chosen as a consolidant for samples from a -year-old piece of waterlogged Viking Age wood from Slagen prestegård. The penetration of chitosan was determined by freeze-drying the samples and analyzing them using high-performance liquid chromatography (HPLC). It was found that chitosan solution penetrated at least  cm into the wood along the grain over the span of  weeks. Depolymerizing the chitosan only improved uptake slightly. The chitosan left an open structure in the waterlogged archaeological wood. It offered some strength to severely degraded waterlogged wood, but further tests are needed to evaluate stability, shrinkage, and fixation.

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