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Licensed Unlicensed Requires Authentication Published by De Gruyter July 26, 2016

Thermal modification of wax-impregnated wood to enhance its physical, mechanical, and biological properties

  • Miha Humar EMAIL logo , Davor Kržišnik , Boštjan Lesar , Nejc Thaler , Aleš Ugovšek , Klemen Zupančič and Mojca Žlahtič
From the journal Holzforschung


Thermal modification is the most important commercial modification procedure. Thermally modified (TM) wood has improved durability, but its performance does not meet expectations predominately under moist conditions. To reduce water uptake of TM wood, Norway spruce specimens were treated with suspensions of a natural wax by dipping impregnation (DipI) or by vacuum-pressure impregnation (VPI). Wax-treated specimens were subsequently TM at 185, 200, 215, and 230°C. Control specimens were heated up to 100°C only. Contact angle (CA), short-term and long-term water uptake, bending strength, and performance against wood decay fungi of the resulting material were determined. The results show that a combination of wax treatment and thermal modification have a synergistic effect that considerably improves hydrophobicity, reduces liquid water uptake, slows down water vapor uptake, and improves the resistance against fungal decay of the treated material.


The authors acknowledge the support of the Slovenian Research Agency within the framework of project L4-5517, L4-7547, program P4-0015 and the infrastructural centre for preparation, weathering and field-testing of wood and lignocellulosic materials (IC LES PST 0481-09). The work was part financed by the European Union, project “WINdow based on THERmally modified wood with high performance WAX coating” (WINTHERWAX, 666206).


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Received: 2016-4-6
Accepted: 2016-6-20
Published Online: 2016-7-26
Published in Print: 2017-1-1

©2017 Walter de Gruyter GmbH, Berlin/Boston

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