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Wood that is used in outdoor applications is frequently exposed to weathering and is thus prone to fungal degradation. Ways to prevent fungal degradation include keeping the wood dry. The majority of hydrophobic and wood modification systems have been tested only on freshly treated wood. Little information is available on how various woodbased materials perform after a certain period of weathering. To elucidate this question, 17 wood samples were tested from the following species: oak (Quercus), sweet chestnut (Castanea sativa), European larch (Larix decidua), Scots pine heartwood and sapwood (Pinus sylvestris), Norway spruce (Picea abies), and beech (Fagus sylvatica). Moisture performance of the wood samples was improved with thermal modification, wax, oil, and biocide treatment. Specimens were exposed to various degradation-aging factors (blue stain fungi, decay fungi, artificial weathering, and natural weathering). Various moisture performance tests were applied before and after aging: short-term water uptake (tensiometer), long-term water uptake, water vapor tests, drying tests, etc. The water exclusion efficacy of wood was decreased after aging. Aging factors were found to act synergistically and to have a more prominent influence on less durable wood compared to durable or preservative-treated wood. Wax-treated wood performed best, regardless of which moisture performance test was applied. [ABSTRACT FROM AUTHOR]

The use of wood in outdoor, above-ground applications is increasing in Europe. To further increase wood usage, more information related to service life and maintenance costs must be provided. Water exclusion efficacy (WEE) is one of the most important factors influencing service life and strongly correlates to wood moisture dynamics, surface properties, and hydrophobicity (WEE as a whole). WEE can be improved with modifications and hydrophobic treatments. The aim of this study was to elucidate which wood surface properties affect WEE and to note changes over time caused by artificial or natural aging. Wood samples of oak (Quercus), sweet chestnut (Castanea sativa), European larch (Larix decidua), Scots pine heartwood and sapwood (Pinus sylvestris), Norway spruce (Picea abies), and beech (Fagus sylvatica) were used to investigate this phenomenon. The moisture performance of the wood samples was improved with thermal modification, wax, oil, and biocide treatment. In total, 17 materials were prepared. After treatment, four different aging procedures were applied. Before and after aging, Fourier transform infrared spectra, colour, and contact angle were determined. The analysis of untreated wood based materials indicated that durability and hydrophobicity are related. Of all the treatments, wax performed the best and retained high hydrophobicity even after the most severe aging method (outdoor exposure). [ABSTRACT FROM AUTHOR]

Sweet chestnut ( Castanea sativa ) heartwood is one of the most durable European commercial wood species. Various aspects that could potentially influence the durability were studied in the present research: presence of extractives, ring width and weathering. The properties of wood that had been in outdoor use for 35 years were also examined. The results indicate that ring width and weathering (outdoor use) did not influence the durability. None of the fungi used were able to degrade sweet chestnut heartwood in a modified EN 113 experiment. After extraction with methanol or water, specimens lost between 11% and 15% of total mass by leaching of extractives. However, extraction only slightly decreased the durability of the leached wood. This indicates that other components (in addition to water and methanol soluble extractives) could be responsible for durability. Furthermore, analysis of 35-year-old wood showed that not all relevant properties of the old sweet chestnut wood deteriorated within the mentioned time frame. This proves that old sweet chestnut hardwood can potentially be reused for a variety of applications. [ABSTRACT FROM AUTHOR]