Organosilicon compounds with various active groups as consolidants for the preservation of waterlogged archaeological wood

Abstract

Abstract Waterlogged wood conservation focuses primarily on its dimensional stabilisation to prevent irreversible deformations that occur upon drying. It also aims to solve the concerns regarding wood degradation as well as its physico-mechanical properties, all of which are inextricably connected with wood hygroscopicity. Therefore, the reduction of wood hygroscopicity can provide a solution to some of the conservation problems. Due to the hydrophobising properties and the ability to cell wall bulking, a set of organosilicons with various active groups were selected to evaluate their stabilisation effect on highly degraded medieval waterlogged elm wood. Exceptionally satisfying results were obtained for (3-Mercaptopropyl)trimethoxysilane, 1,3-Bis(diethylamino)-3-propoxypropanol)-1,1,3,3-tetramethyldisiloxane and Methyltrimethoxysilane, for which the volumetric anti-shrink efficiency was around 98%, 90% and 81%, respectively. Additionally, the applied treatment resulted in a decrease of wood moisture content from 6.7% for untreated wood to 2.4–3.6% for wood treated with the above-mentioned compounds. Neither the alkoxysilanes with a long alkyl chain, nor those terminated with a highly hydrophilic pyridine ring were found effective for waterlogged wood stabilisation. It can be concluded that the organosilicon compounds with alkoxy groups and a relatively short alkyl chain or containing and additional chemical group enable to form stable bonds with wood components proved to be the most effective wood stabilisers.