Artificial Weathering Resistance and Biological Durability of Surface-Charred Beech Wood Combined with Linseed Oil Coating

Specimens of European beech wood (Fagus sylvatica L.) charred at 250 °C (4 min), 300 °C (2 min), and 350 °C (1 min) in combination with linseed oil coating were studied. The influence of the surface charring process and artificial weathering on surface discoloration, water absorption, and decay resistance were analyzed. Discoloration analysis showed a decrease in all parameters L*, a*, and b* due to the charring process. Coating with linseed oil caused a decrease in the L* parameter. An influence on parameters a* and b* was also demonstrated. As a result of the artificial weathering, the L* parameter increased in almost all groups. The group charred at 350 °C showed a decrease in L*. The parameters a* and b* were also affected. The effect of oil coating on discoloration during artificial weathering was negligible. The average water absorption of uncoated charred specimens decreased more than 50%. Damage due to artificial weathering disrupted the effect of the charring process. The effect of oil coating decreased depending on the length of partial immersion. Surface charring and oil impregnation slightly reduced the loss of beech wood mass caused by T. versicolor and P. placenta but could not fully protect the wood.