Changes in wood durability due to leaching of biologically active substances (extractives) resulting from weathering

Wood durability is vital for its long-term performance in outdoor applications, influenced by various factors. This study investigates the impact of leaching biologically active substances due to weathering on wood durability. The research covers multiple wood species and treated wood subjected to natural and accelerated weathering. Chemical analysis includes extraction, spectrophotometry (UV-Vis), chromatography (HPLC), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray fluorescence spectroscopy (XRF). Additionally, fungal and wetting ability tests were conducted. Results indicate significant extractive leaching during weathering. However, the part of the extractives with the highest biological activity, i.e. the phenolic compounds, were slightly less susceptible to leaching than other extractives. While FTIR analysis suggests minimal degradation of other wood compounds, accelerated weathering induced notable extractive loss. Weathering adversely affected inherent durability and wetting ability, leading to reduced relative resistance dose according to the Meyer-Veltrup model. Black locust exhibited the least reduction, while pine heartwood showed the highest decrease in resistance dose. Paste tests revealed fungicidal components' contribution to wood durability, indicating its multifaceted nature. This comprehensive study sheds light on the intricate dynamics between weathering, extractive leaching, and wood durability, offering insights crucial for optimizing wood treatment and preservation methods in outdoor environments.