Methyltrimethoxysilane as a stabilising agent for archaeological waterlogged wood differing in the degree of degradation

Experiments using archaeological wooden remains of a medieval "Poznan" bridge from the Lednica Lake, Wielkopolska Region, Poland, were performed to evaluate the stabilisation effect of methyltrimethoxysilane on waterlogged oak wood varied in the degree of degradation. Moreover, two types of treatment were compared: the soaking method and the oscillating pressure method, preceded by the ethanol dehydration procedure. The results suggest that the silane in question can effectively penetrate wood cell walls, causing their bulking and thus enhancing wood dimensional stability. Exceptionally satisfying results were obtained for severely decayed sapwood (loss of wood substance about 80%), for which an overall anti-shrink efficiency oscillated around 100%, regardless of the applied treatment method. In the case of almost non-degraded heartwood, resistant to impregnation, the obtained anti-shrink efficiency of over 60% could also be considered as quite satisfactory. Comparable values of weight percent gain and anti-shrink efficiency for silane-treated specimens clearly show that there is no significant difference in the efficacy of the soaking and the oscillating pressure method applied. The obtained results show that the methyltrimethoxysilane treatment preceded by wood dehydration could be a reliable method for stabilisation of small archaeological waterlogged wooden artefacts, providing their good dimensional stability of wood differing in the degree of degradation. (C) 2018 Elsevier Masson SAS. All rights reserved.