Water Absorption Capacity and Coating Adhesion on Thermally Modified and Not-Modified Spruce Wood (Blue Stained or Free of Blue Stained)

This study aimed to investigate the water absorption capacity of thermally modi fi ed and non-modi fi ed spruce and blue-stained spruce wood. The wettability of wood depends on various factors, including its type, density, porosity, and surface treatment. Wood can swell and become distorted when exposed to water or humidity, impacting its structural integrity. Hence, it is crucial to consider the water and water vapour uptake in the wood when choosing materials for applications that are likely to be exposed to moisture. Various moisture absorption tests were conducted to assess water absorption capacity, including short-term and long-term water absorption and water vapour absorption. The results showed a signi fi cant difference in the long-term exposure to water, which was related to the density of the wood. The study examined the in fl uence of thermal treatment on the physical properties of wood and observed signi fi cant variations in mass change due to coating, indicating differences in adhesion among different wood types. Vacuum-treated blue-stained Norway spruce demonstrated higher adhesion (5% – 15%) compared to air-treated samples. Furthermore, cohesion tests revealed lower cohesion force in blue-stained Norway spruce (approximately 20% – 30%) compared to Norway spruce. The study also used indus-try-standard tests to investigate the adhesion and cohesion of nano-coatings on wood surfaces. The results provided valuable information on the properties of coatings applied to wood, which is vital in protecting and decorating wood while also providing preventive protection against wood pests, weathering, and mechanical in fl uences. Wood modi fi cation in vacuum involves subjecting the wood to a low-pressure environment to remove air and moisture, allowing for deeper and more uniform penetration of treatment chemicals. In contrast, wood modi fi cation in air relies on the natural circulation of air to facilitate the absorption of chemical treatments, without the need for a vacuum chamber.