Comprehensive tests need to be performed to obtain the most accurate data possible on the durability of wood. The most reliable performance tests are field tests. However, since this is very time-consuming, we frequently rely on laboratory tests. To increase the reliability of the laboratory tests, samples are preconditioned with natural or artificially accelerated weathering methods that simulate naturally occurring factors. This research aims to introduce accelerated weathering, defined in the standard EN 16755 (CEN 2017), to simulate the leaching of biologically active substances from wood. It is performed in several weekly cycles that include the effects of wetting, drying and temperature. Accelerated weathering was compared to natural weathering. Mass loss due to weathering was determined on non-weathered and weathered samples. Their extractives and polyphenols contents were determined gravimetrically and spectrophotometrically, respectively. In addition, their durability to Trametes versicolor, Rhodonia placenta, and Gloeophyllum trabeum was also performed. For most species, mass loss was comparable after 6 cycles of accelerated weathering and after 6 months of natural weathering. The same was true for mass loss after 12 cycles and 12 months. However, after 12 months of natural weathering, the levels of extractives or polyphenols were equal to those after 6 cycles of accelerated weathering. The same was true for resistance to the tested fungi. Therefore, to monitor changes in fungal resistance due to weathering, 6 cycles of accelerated weathering rather than 12 months of natural weathering can be used to obtain comparable results. Research results have also shown that we can better describe changes in wood by monitoring extractive content than by monitoring mass losses.

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