Oak-wood is considered as one of the most durable Slovenian domestic wood species. There were several reports about natural durability of products made of oak. In the past research on oak-wood durability, the most important factor influencing wood durability was assigned to extractives. It was proved that the extractives had a large influence on natural durability, nevertheless, just this parametre did not suffice to elucidate the differencesregarding the behaviour of samples. To find out if oak-wood durability can also be affected by ring-widths or density, oak-wood specimens were prepared from boards with different ring-widths, and exposed to 5 different fungal species, according to the EN 113 standard procedure. In parallel, extractives, nitrogen, lignin content, chemical properties (FTIR), and colour of the specimens were determined as well. From gravimetrically determined mass losses, and microscopy analysis of decayed specimens, it can be resolved that oak wood specimens with the narrowest rings are more susceptible to fungal decay than specimens made of average or wide ring-widths. Durability of oak-wood with average rings width of 0.77 mm is comparable to durability of beech-wood. Furthermore, our results indicate that influence of extractives on wood durability is important as well.
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