Application of methyltrimethoxysilane to increase dimensional stability of waterlogged wood

Conservation of historic wooden monuments, especially regarding waterlogged archaeological wood, is a complex, long-term, multi-stage and also a quite difficult process. The main problem is poor dimensional stability of such artefacts due to a high degree of wood tissue degradation and its significant saturation with water. Exposing wood to a natural drying process causes its shrinkage, cracking and irreversible deformation due to collapse. Therefore, the first stage of maintenance of waterlogged wooden objects is to replace the water filling cell lumina and cell walls with an appropriate consolidation agent that will protect wood against shrinkage, collapse and loss of shape. Silanes have so far been used mainly as additives for wood preservatives and coatings, increasing wood hydrophobicity or decreasing its hygroscopicity. Some silanes show resistance to biotic degradation. As confirmed in scientific reports, their ability to improve dimensional stability of contemporary wood makes them a potential agent for stabilisation of archaeological wood. The aim of the research was to determine the influence of methyltrimethoxysilane (MTMOS) treatment on the dimensional stability of waterlogged elm wood excavated from the Lednica Lake in the Wielkopolska Region. Freshly taken from the lake and still completely saturated with water, elm wood samples were treated with ethanol solution of 50% MTMOS by the vacuum-pressure impregnation method. Pre- and post-treatment dimensions of wood samples were measured and anti-shrink efficiency (ASE) was calculated. ASE values of elm wood treated with MTMOS varied from 69.4% to 94.5%, depending on the state of wood degradation. In case of reference wood samples treated with polyethylene glycol, ASE ranged between 96.1% and 100%. Taking into account the improvement of wood dimensional stability obtained, the aesthetic end result of the treatment and its properties of hydrophobicity and antifungal activity, the silane MTMOS can be considered as a potential agent for conservation of waterlogged wood and seems to be worth further study.