Effects of Different Orientations and Treatments in an Outdoor Natural Aging of Japanese Cryptomeria and Scots Pine Wood

Wood is an excellent material in terms of sustainability; however, for durability reasons, it is critical to understand its aging over time, especially in outdoor spaces. Maximizing the lifespan of outdoor timber requires identifying the primary drivers of early-stage deterioration. This understanding ensures the selection of the most effective treatment and maintenance strategies. For this purpose, a natural aging exposure test was conducted on 32 samples of Cryptomeria wood and Scots pine, with 4 different solar orientations and 4 treatments, in a coastal area. To assess material behavior during the early stages of exposure without maintenance intervention, degradation was recorded over the initial 2 years of exposure. Those records were made based on visual analyses and classification tables for abiotic and biotic degradation, complemented by colorimetry to determine the specific effects of UV-induced photodegradation. The results obtained underline the importance of anti-tannin impregnation in the treatment process and demonstrate that treated pine wood shows greater color variations than treated Cryptomeria wood. This study reaffirms the indispensability of wood protection systems and suggests that reapplication must occur early in the service life to mitigate initial deterioration.