Bio-oils as coatings for mitigating deterioration of wood from artificial weathering

Abstract Wood weathering is an abiotic deterioration process influenced by environmental factors, including but not limited to UV radiation, oxidation, and moisture, which significantly impacts wood’s structural integrity, dimensional stability, surface quality, and aesthetic. This study investigates the performance of bio-based oils, including seed oils, pyrolysis bio-oils, and pine tars, as a sustainable renewable solution to mitigate damage to wood caused by weathering. Enhancing the performance of pyrolysis oils and pine tars as wood coatings through the addition of linseed oil was also investigated. Wood samples treated with various organic coatings were subjected to artificial weathering for 8 weeks and incrementally tested for changes in mass, hydrophobicity, color, and surface chemistry. Bio-oil coatings were analyzed by gas chromatography/mass spectrometry (GC/MS) to evaluate their composition and draw conclusions on how it impacted their performance as coatings. Linseed oil showed the strongest surface retention and the longest lasting water repellency. All pyrolysis oil treated surfaces became hydrophilic by week 2, both pine tar treated surfaces became hydrophilic by week 4, and treatments containing added linseed oil retained measurable water repellency until week 6. Linseed oil alone retained measurable water repellency longer than any other treatment. After 8 weeks, total oven dry mass loss was 3.81% for the uncoated control, 3.90% for linseed oil, and 4.75–5.22% for the pyrolysis oil treatments. Linseed oil also resulted in the lowest total color change among the coatings tested (ΔE = 13.1 ± 2.3), while pyrolysis oils alone showed substantially greater color change. Results from this study provided insights into optimizing bio-based coatings for sustainable wood preservation.