Durability of European oak (Quercus petraea and Quercus robur) against white rot fungi (Coriolus versicolor):: relations with phenol extractives

Knowledge on wood natural durability is required in order to be able to decide if we can use a certain type of wood outdoors. For instance, when used outside, oak wood is subjected to the leaching of its water-soluble substances. In this case the resistance of European oak wood is considered to be durable according to the European Standard EN 350-2. However, so far we do not exactly know the real impact of the leaching phenomenon on the resistance of oak wood and the importance of chemical contents. Nevertheless, our study has indicated that some individuals may contain highly durable wood characteristics even after the leaching process (i.e. 33% of very durable wood was still very durable after the leaching test). Chemical analysis has demonstrated that the presence of phenolic compounds are positively correlated with durability. This means that higher proportions of phenol confer higher resistance on wood. After the leaching test, which involves a washout of water soluble compounds, 70% of the trees demonstrate a decline in durability (after the leaching test 75% of the very durable wood dropped to a durable class; whereas, 25% of the wood in the same class still kept their very durable status). This experiment clearly shows the influence of the leaching phenomena and its important role on durability in oak wood. The results show also that 18% of the oak samples could be considered as very durable even after leaching.