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Sodium Alginate as a Green Consolidant for Waterlogged Wood—A Preliminary Study
Traditional consolidants commonly used for waterlogged wood conservation often present long-term drawbacks, prompting research into new and reliable alternatives. Reducing reliance on fossil-based chemicals that are harmful to people, the environment, and the climate is a growing trend, and sustainable materials are now being explored as alternative consolidants for conserving waterlogged archaeological wood. Among these bio-based products, sodium alginate, a natural polysaccharide, has shown promising potential. This study aimed to evaluate its effectiveness in stabilising dimensions of severely degraded archaeological elm wood during drying. Various treatments were tested, and dimensional stabilisation (ASE), weight percent gain (WPG), and volumetric shrinkage (Vs) were assessed. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to evaluate alginate penetration and interactions with residual wood components. Results indicated that the effectiveness of sodium alginate depends on the treatment method, with the soaking approach and slow drying providing the highest WPG and the best stabilisation without altering the natural wood colour. Although the best achieved anti-shrink efficiency of 40% is insufficient from the conservation perspective, sodium alginate has proven to be a promising consolidant for the conservation of waterlogged wood. Further studies will focus on enhancing its penetration and interactions with residual wood components.
Reactivity of Waterlogged Archeological Elm Wood with Organosilicon Compounds Applied as Wood Consolidants: 2D 1H–13C Solution-State NMR Studies
Some organosilicon compounds, including alkoxysilanes and siloxanes, proved effective in stabilizing the dimensions of waterlogged archaeological wood during drying, which is essential in the conservation process of ancient artifacts. However, it was difficult to determine a strong correlation between the wood stabilizing effect and the properties of organosilicon compounds, such as molecular weight and size, weight percent gain, and the presence of other potentially reactive groups. Therefore, to better understand the mechanism behind the stabilization effectiveness, the reactivity of organosilicons with wood polymers was studied using a 2D 1H–13C solution-state NMR technique. The results showed an extensive modification of lignin through its demethoxylation and decarbonylation and also the absence of the native cellulose anomeric peak in siloxane-treated wood. The most substantial reactivity between wood polymers and organosilicon was observed with the (3-mercaptopropyl)trimethoxysilane treatment, showing complete removal of lignin side chains, the lowest syringyl/guaiacyl ratio, depolymerization of cellulose and xylan, and reactivity with the C6 primary hydroxyls in cellulose. This may explain the outstanding stabilizing effectiveness of this silane and supports the conclusion that extensive chemical interactions are essential in this process. It also indicates the vital role of a mercapto group in wood stabilization by organosilicons. This 2D NMR technique sheds new light on the chemical mechanisms involved in organosilicon consolidation of wood and reveals what chemical characteristics are essential in developing future conservation treatments.