Modification of Scots pine (Pinus sylvestris L.) sapwood using aqueous formulations of Na₂SiO₃ via vacuum-pressure technique and subsequent treatment with cashew nut-shell liquid (CNSL) is reported. Morphology, elemental distribution within wood matrix, and structural properties of wood-composites were investigated by FE-SEM/EDS, FTIR analysis. Microstructure and density of modified wood blocks were further assessed by X-ray computed tomography. The flammability of Na₂SiO₃-CNSL-wood composites was evaluated simultaneously performing thermogravimerical (TG) and FTIR gas analysis; the results showed that maximum weight loss for the modified wood was obtained at up to 70 °C lower temperatures compared to the untreated wood, whilst substantially reducing terminal weight losses. The coefficient of friction significantly increased after the CNSL treatment compared to that of untreated wood, but addition of Na₂SiO₃ to CNSL eliminated most of the friction increase. Enhanced tribological properties along with industrial wood-impregnation method suggest that wood modification using Na₂SiO₃ in combination with CNSL has a potential for the exploration of a broader range of wood material properties in agreement with sustainable material management.