The effect of silane modification on selected properties of gap fillers for wooden artefacts exposed outdoors

Wooden artefacts exposed outdoors often need proper gap fillers to fill holes and fissures in their structure, ensuring their integrity and preserving them for future generations. This research investigates the effect of modification with silanes (Methyltrimethoxysilane (MTMOS) and (3-Glycidyloxypropyl)trimethoxysilane (GOPTMOS)) on the properties of gap fillers based on wood powder or glass microballoons as a filler and Paraloid B-72, Klucel G or glutin glue as a binder. The dimensional stability of filling masses during drying and exposure to high moisture and water immersion was evaluated, along with their wettability, thermal stability and mechanical properties. Infrared spectroscopy was used to analyse the chemical interactions between constituents of prepared gap fillers. Additionally, parameters important from the conservator's perspective were evaluated, including workability and ease of surface finishing. The overall results indicate that the effect of silane does not provide consistent results. It depends on the type and concentration of a silane, and the type and amount of a filler and a binder. MTMOS generally gave better results than GOPMOS, and the best properties were reported for composites based on glass microballoons and Paraloid. Silane modification improved the water and moisture resistance of most gap fillers, particularly those based on microballoons with Paraloid B-72, and wood powder with Klucel G or glutin glue, without significantly compromising their mechanical and thermal properties, workability and finishability. All these show their potential as additives for filling materials intended for the conservation of wooden artefacts exposed outdoors.