The importance of the aesthetic performance of wood is increasing and the colour is one of the most important parameters of aesthetics, hence the colour stability of twelve different wood-based ...materials was evaluated by several in-service and laboratory tests. The wood used for wooden façades and decking belongs to a group of severely exposed surfaces. Discolouration of wood in such applications is a long-known phenomenon, which is a result of different biotic and abiotic causes. The ongoing in-service trial started in October 2013, whilst a laboratory test mimicking seasonal exposure was performed in parallel. Samples were exposed to blue stain fungi (Aureobasidium pullulans and Dothichiza pithyophila) in a laboratory test according to the EN 152 procedure. Afterwards, the same samples were artificially weathered and re-exposed to the same blue stain fungi for the second time. The purpose of this experiment was to investigate the synergistic effect of weathering and staining. The broader aim of the study was to determine the correlation factors between artificial and natural weathering and to compare laboratory and field test data of fungal disfigurement of various bio-based materials. During the four years of exposure, the most prominent colour changes were determined on decking. Respective changes on the façade elements were significantly less prominent, being the lest evident on the south and east façade. The results showed that there are positive correlations between natural weathering and the combination of artificial weathering and blue staining. Hence, the artificial weathering of wood-based materials in the laboratory should consist of two steps, blue staining and artificial weathering, in order to simulate colour changes.
Wood-based materials are CO2-neutral, renewable, and considered to be environmentally friendly. The huge variety of wood species and wood-based composites allows a wide scope of creative and esthetic ...alternatives to materials with higher environmental impacts during production, use and disposal. Quality of wood is influenced by the genetic and environmental factors. One of the emerging uses of wood are building and construction applications. Modern building and construction practices would not be possible without use of wood or wood-based composites. The use of composites enables using wood of lower quality for the production of materials with engineered properties for specific target applications. Even more, the utilization of such reinforcing particles as carbon nanotubes and nanocellulose enables development of a new generation of composites with even better properties. The positive aspect of decomposability of waste wood can turn into the opposite when wood or wood-based materials are exposed to weathering, moisture oscillations, different discolorations, and degrading organisms. Protective measures are therefore unavoidable for many outdoor applications. Resistance of wood against different aging factors is always a combined effect of toxic or inhibiting ingredients on the one hand, and of structural, anatomical, or chemical ways of excluding moisture on the other.
This study was performed to understand the interaction between Ophiostomataceae and basidiomycetes fungi during cultures, and whether the basidiomycetes fungi inhibit the growth and decolorize dark ...pigments of blue staining fungi. The conjoint cultivation was studied on 2% malt extract agar. The ability of basidial cultures to decolorize dark pigments of ophiostomatoid fungi was the main characteristics estimated during this study. More than half of basidial cultures were characterized by deadlock interaction with blue staining fungi. In the dual cultures, where basidial partners were presented by Agaricus bisporus(64), Laetiporus sulphureus(L01/89), Trametes versicolor(09) and unknown fungus(02), antagonism was found at the phase of primary contact of colonies. Replacement interaction resulted usually in decreasing dark colour of substrate was observed for 11 basidial cultures that were belonging mainly to white-rot fungi. Among them Abortiporus biennis(123), Antrodiella hoehnelii(S28/91), Bjerkandera fumosa (137), and Gleophyllum odoratum(124) were characterized by the absence of deadlock-phase: they began to grow over dark colonies of their partners just after primary contact. Basidiomycetes did not affect strongly the pigments of Ceratocystis spp. and Leptographium sibirica isolates, but completely decolorized colonies of Ophiostoma ips and to a smaller degree Ophiostoma minus. Antrodiella hoehnelii(S28/91), Bjerkandera fumosa(137), Gleophyllum odoratum(124) and Trametes versicolor(B18/91) cultures were found to be the most active in decreasing dark color of blue staining fungi colonies. The cultures were recommended for further development as agents of biopulping of wood chips and bio-control of blue stain in woods.
This study was performed to investigate the frequency of blue staining fungal species collected from pine trees, Experimental Forests of Kangwon National University in Korea based on their ...morphological characteristics. In addition the tolerance to fungicide, Woodguard, was assessed to get basic knowledges for preventing blue stain of wood. Totally Leptographium-type fungi were dominated by 79.3% among Ophiostomatoid fungi associated with scolityd bark beetles in pine trees. Leptographium-type Ds-isolates which have unusual morphology were collected as frequency of 17.0%. The most distinct differeneces of these Ds-isolates from L. procerum were the presence of roughened hyphae and flask-shaped conidiophores that have never been mentioned formerly for L. procerum, but since these Ds-isolates formed black concentric rings being a property of L. procerum, the Df-isolates were characterized as Leptographium-type fungi, which are the most common species with the highest frequency by 33.2% in this particular area. According to our experimental results, Leptographium-type Ds- and Df-isolates were very resistant to fungicide, Woodguard, therefore it was suggested that a new method for wood protection from the blue staining fungi should be developed. Exact identification of blue staining isolates collected from pine trees is keep going.
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