While renovating the vineyard in the upper Vipava Valley, we removed 40-year-old black locust (Robinia pseudoacacia) posts. The wood which was used for comparison purposes was obtained from a nearby forest. We visually inspected and assessed the posts for rot decay using the SIST EN 252 standard. We took sections from the posts and brought them to the laboratory, where they were cut into appropriately sized samples. In addition, natural durability, water exclusion efficacy, and the contact angle between water and wood were determined, and FTIR and XRF spectra were recorded. The cross-sections were analysed using digital microscopy, and the degradation rate was evaluated on the cross-sections. The experiments led us to conclude that after 40 years of use, the wood is still of better quality than recent Robinia wood. The reason for the better characteristics of old compared to new wood is primarily the former’s slower growth, which indirectly influences the higher density, the higher proportion of extractives, and ultimately the better mechanical and biological resistance of the wood.
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