Evaluation of sol-gel hybrid nanocomposites for dry medieval wood

Viking Age archaeological wooden objects from the Oseberg find have undergone extensive chemical de- terioration due to the original conservation treatment, based on alum salts (KAl(SO 4 ) 2 ·12H 2 O), done in the early 1900s. Today, the artefacts are highly acidic (pH ≤ 2), fragile and the wood has almost com- pletely lost its structural integrity. This study is part of a wider research project on conservation methods for these finds, currently underway. Multi-functional organic/inorganic hybrid systems, engineered to deacidify and consolidate alum- treated wood in a single step, have been studied. These products, made of a polysiloxanes’ network and nanostructured Ca(OH) 2 , have given promising results in terms of penetration, deacidification, consolida- tion and maintenance of the wood properties. This work provides a comparison between two hybrid systems having in common a backbone of poly(dimethylsiloxane) hydroxy–terminated (PDMS-OH) and alkaline nanoparticles (NPs) (as deacidify- ing agent), along with tetraethyl orthosilicate (TEOS), methyltriethoxysilane (MTES) applied to fresh and archaeological wood, respectively. Colour, pH, dimensions, SEM-EDS and ultrasonic velocity measurements, in addition to hardness tests, were collected on the treated mock-ups to investigate the outcomes of the two systems in terms of con- servation efficacy. FTIR-ATR and DVS have also been carried out for systems characterization. From the analysis performed, the most promising hybrid system seems to be the one prepared with MTES as struc- tural polymer. In addition, it has been highlighted the requirement of a method for sol application other than immersion when objects are already treated with resins.