Abstract
The problem with discoloration, due to fungal growth, of wooden outdoor constructions seems to have increased in recent years. One reason for this increase might be an impact of new drying methods of timber. Modern kiln drying methods use high temperatures in an effort to shorten the drying process, which leads to fast capillary water transport and subsequently redistribution and accumulation of dissolved substances at the surface. These can then be used as nutrients by fungi. In this study, wood was dried according to different simulated drying schedules. The mould resistance of the timber was then tested. Wood dried at room temperature was used as a reference. No differences could be confirmed at the end of the test; mould growth was extensive on all the samples. However, mould growth started earlier on the kiln-dried samples than on air-dried timber. As for the discolouring fungus, there was a clear difference between wood dried at room temperature and kiln-dried wood, though no difference could be established between the two artificial methods.
Zusammenfassung
In den letzten Jahren ist eine Zunahme des Verfärbungsproblems bei Holzkonstruktionen im Außenbereich aufgrund von Pilzbefall zu verzeichnen. Als ein Grund dafür wurde der Einfluss neuer Trocknungsmethoden von Schnittholz genannt. Moderne technische Trocknungsverfahren verwenden hohe Temperaturen, um die Trocknungszeit zu verkürzen. Dies führt zu schnellem Kapillarwassertransport und dadurch zu einer Verlagerung und Akkumulierung gelöster Stoffe an der Oberfläche, welche dann den Pilzen als Nährstoffe dienen. In dieser Studie wurde Holz mittels verschiedener Trocknungsabläufe getrocknet und anschließend auf Schimmelbeständigkeit geprüft. Bei Raumtemperatur getrocknetes Holz diente als Kontrollprobe. Bei Versuchsende konnten keine Unterschiede festgestellt werden; alle Prüfkörper wiesen starkes Schimmelwachstum auf. Allerdings begann das Schimmelwachstum bei technisch getrockneten Prüfkörpern früher als bei luftgetrocknetem Schnittholz. Bei den holzverfärbenden Pilzen gab es einen deutlichen Unterschied zwischen Holz, das bei Raumtemperatur getrocknet wurde, und technisch getrocknetem Holz. Jedoch konnte kein Unterschied zwischen den beiden technischen Trocknungsprogrammen festgestellt werden.
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Acknowledgments
The present research was part of the research programme WoodBuild co-ordinated by SP Technical Research Institute of Sweden. The research was financed by VINNOVA, the Swedish Federation of Forest Industries, and a number of companies in the forest and building sector.
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Johansson, P., Wamming, T., Bok, G. et al. Mould growth on kiln-dried and air-dried timber. Eur. J. Wood Prod. 71, 473–481 (2013). https://doi.org/10.1007/s00107-013-0699-y
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DOI: https://doi.org/10.1007/s00107-013-0699-y