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Laccase treatment of Norway spruce wood surface improves resistance and copper fixation of treated wood

Vaukner Gabrič M., Boncina T., Humar M., Pohleven F.

Drewno : prace naukowe, doniesienia, komunikaty

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2016

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vol. 59, nr 198

19--33

EN

The effects of laccase from the white-rot basidiomycete fungus Trametes versicolor on Norway spruce wood (Pices abies) surface were studied. Experiments were performed at room temperature and at pH 4.6, without the addition of mediators. Biological, chemical and physical properties of the treated wood surface were examined by a wood decay test, a scanning electron microscopy (SEM), a Fourier transform infrared (FTIR) spectroscopy and a copper leaching test. Laccase pre-treatment of Norway spruce wood surface was shown to reduce wood decay by brown-rot fungus, Gloeophyllum trabeum and white-rot fungus, Trametes versicolor. SEM images showed expanded wood cell walls, closed pits and a more even surface after laccase treatment. FTIR analysis indicated that laccase not only catalyse depolymerisation of lignin, but also affect other wood cell wall components, such as hemicellulose and cellulose. We showed that laccase treatment altered wood properties in a way that improved wood resistance to decay and prevented leaching of copper from impregnated wood.

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Protection through construction of a wooden monument in Radomlje (Slovenia)

Pamić R., Pohleven F.

Drewno : prace naukowe, doniesienia, komunikaty

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2015

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vol. 58, nr 195

135--148

EN

Biodegradation of the wood, photo-degradation of the coatings and major cracks appeared on a six-metre high oak monument built in 1960. Due to three displacements and exposure to increased moisture and pests, the monument lost its original appearance. Damage due to the fixation elements became so extensive that they threatened its load-bearing capacity. During the renovation work, the monument was subjected to original and specific constructional measures and its original appearance was restored. Restoration of the original details allowed water to flow off the monument easily, hence the wood could dry quickly. The weakened and worn parts of the wood were replaced or consolidated. Dilatation between the wood, metal and stone was stopped and further corrosion processes prevented. Restoration of the cracks prevented the entry and retention of water inside. Where this was not achievable, drainage was installed and aeration of the wood was enabled. By means of a central metal mandrel and a supporting system of adjustable bolts, the bearing capacity was improved and, in the event of possible displacements, centring of the monument was made possible. Removing the external fixation elements contributed to the monument’s aesthetics. These innovative construction solutions may represent a model case for the future restoration of similar cultural monuments.

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Degradation of some technological features in the wood of ornamental species caused by Inonotus rickii (Pat.) Reid

Annesi T., Calienno L., Picchio R., De Simone D., Lo Monaco A.

Drewno : prace naukowe, doniesienia, komunikaty

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2015

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vol. 58, nr 195

5--18

EN

Inonotus rickii (Pat.) Reid is a pathogenic wood-decaying fungus that causes severe decay in several ornamental urban trees in Europe. It has been known to occur on different hosts in Sicily (Italy) since 1985, and in Rome (Italy) since 2003. Some physical and mechanical wood features were studied according to the standards in order to propose an investigation methodology to set a deterioration ranking of urban trees. In this phase of the study, Celtis australis L., Acer negundo L., Acer campestre L., Robinia pseudoacacia L., Tilia × vulgaris Hayne, Ulmus minor Mill., Platanus × acerifolia (Aiton) Willd. and Quercus ilex L. were studied. The data were analyzed using ANOVA and M-ANOVA tests to check the differences among the specimens. A risk matrix was created in order to combine the features that showed statistical differences between the control specimens and the inoculated specimens, in order to establish, in vitro, a degradation ranking among the wood species. The wood species which showed no in vitro durability to I. rickii, were the same ones that displayed susceptibility in the living trees.