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Water repellents, as environmentally-friendly treatments, are gaining popularity as non-biocidal solutions for wood protection. Drying oils, in addition to waxes and organosilicon compounds, are one of the most important water repellents for wood. Tung oil has so far been proven to be one of the best performing oils for wood protection. However, tung oil, similarly as other oils, does not penetrate deeply into wood, due to its high viscosity. In order to improve the penetration of oil into wood, a vacuum-pressure procedure has to be applied. The species used in this study are important in Central Europe: sweet chestnut heartwood ( Castanea sativa ), European larch heartwood ( Larix decidua ), Scots pine heartwood and sapwood ( Pinus sylvestris ) and Norway spruce ( Picea abies ). Oil uptake depends on the applied impregnation method and on the wood species used. Retention of tung oil was higher after an impregnation process than with the immersion procedure. Magnetic resonance imaging (MRI) was applied to elucidate the influence of wood species on oil penetration and distribution in wood after treatment. High spatial resolution MR imaging is highly sensitive to changes of liquids in wood and is therefore also very appropriate for monitoring oil penetration. Furthermore, with a good signal to noise ratio of MR images, the method can also discern among specimens with different patterns of oil distribution, as well as between areas of early-wood and late-wood. [ABSTRACT FROM AUTHOR]

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]