Skip to content
Licensed Unlicensed Requires Authentication Published by De Gruyter January 28, 2016

Thermo-hydro treated (THT) birch veneers for producing plywood with improved properties

  • Juris Grinins EMAIL logo , Bruno Andersons , Ilze Irbe , Ingeborga Andersone , Anete Meija-Feldmane , Anna Janberga , Gunars Pavlovics and Errj Sansonetti
From the journal Holzforschung


The effect of thermo-hydro treatment (THT) on the properties of birch (Betula spp.) wood veneers has been studied. THT was carried out in a multi-functional pilot scale wood modification device of wood treatment technology (WTT, Latvia) under elevated water vapor pressure conditions at four combinations of temperature and treatment time (°C/min): 150/10; 150/50; 160/10 and 160/50. After THT, the following veneer properties were examined: mass loss (ML), chemical composition, bending strength (BS), tensile strength (TS), equilibrium moisture content (EMC), resistance to decay by mould and blue stain fungi, and surface contact angle (CA). The chemical components were changed by THT. Increased THT temperature and time resulted in hydrophobization of veneers as indicated by decreasing EMC and increasing CA data. All THT were effective against wood discoloring fungi, although insufficient decay resistance was observed. The mechanical strength properties of THT veneers were also deteriorated.

Corresponding author: Juris Grinins, Latvian State Institute of Wood Chemistry, 27 Dzerbenes Str., LV-1006 Riga, Latvia, e-mail:


The authors gratefully acknowledge the financial support by the European Regional Development Fund project “Plywood from thermally modified veneer with improved durability properties” No. 2014/0018/ 2DP/ We would also like to express special thanks to Kristine Meile for analysis of water extractives and Andis Antons for help in mechanical tests.


Alén, R., Kotilainen, R., Zaman A. (2002) Thermochemical behavior of Norway spruce (Picea abies) at 180–225°C. Wood Sci. Technol. 36:163–171.10.1007/s00226-001-0133-1Search in Google Scholar

Andersons, B., Andersone, I., Biziks, V., Irbe, I., Chirkova, J., Sansonetti, E., Grinins, J., Militz, H. (2010) Hydrothermal modification for upgrading the durability properties of soft deciduous wood. The International Research Group on Wood Protection. Document No. IRG/WP/40494.Search in Google Scholar

Andersons, B., Noldt, G., Koch, G., Andersone, I., Meija-Feldmane, A., Biziks, V., Irbe, I., Grinins, J. (2016) Scanning UV microspectrophotometry as a tool to study the changes of lignin in hydrothermally modified wood. Holzforschung 70:215–22110.1515/hf-2015-0027Search in Google Scholar

Bekhta, P., Niemz, P. (2003) Effect of high temperature on the change in color, dimensional stability and mechanical properties of spruce wood. Holzforschung 57:539–546.10.1515/HF.2003.080Search in Google Scholar

Bekhta, P., Hiziroglu, S., Shepelyuk, O. (2009) Properties of plywood manufactured from compressed veneer as building material. Mater. Des. 30:947–953.10.1016/j.matdes.2008.07.001Search in Google Scholar

Bhuiyan, T., Hirai, N. (2000). Changes of crystallinity in wood cellulose by heat treatment under dried and moist conditions. J. Wood Sci. 51:42–47.10.1007/BF00765800Search in Google Scholar

Biziks, V., Andersons, B., Sansonetti, E., Andersone, I., Militz, H., Grinins, J. (2015). One-stage thermo-hydro treatment (THT) of hardwoods: an analysis of form stability after five soaking-drying cycles. Holzforschung 69:563–573.10.1515/hf-2014-0083Search in Google Scholar

Biziks, V., Van den Bulcke, J., Grinins, J., Militz, H., Andersons, B., Andersone, I., Dhaene, J., Van Acker, J. (2016) Assessment of wood microstructural changes after one-stage thermo-hydro treatment (THT) by micro X-ray computed tomography. Holzforschung 70:167–177.10.1515/hf-2014-0337Search in Google Scholar

Boonstra, M.J., Tjeerdsma, B.F. (2006) Chemical analysis of heat treated softwood. Holz als Roh-Werkst. 64:204–221.10.1007/s00107-005-0078-4Search in Google Scholar

Boonstra, M.J., Van Acker, J., Tjeerdsma, B.F., Kegel, E.V. (2007) Strength properties of thermally modified softwoods and its relation to polymeric structural wood constituents. Ann. For. Sci. 64:679–690.10.1051/forest:2007048Search in Google Scholar

Browning, B.L. Methods of Wood Chemistry, vol. 1. Wiley, New York, 1967.Search in Google Scholar

Büyüksari, Ü., Hiziroglu, S., Akkilic, H., Ayrilmis, N. (2012) Mechanical and physical properties of medium density fiberboard panels laminated with thermally compressed veneer. Compos. Part B-Eng. 43:110–114.10.1016/j.compositesb.2011.11.040Search in Google Scholar

Dieste, A., Krause, A., Bollmus, S., Militz, H. (2009) Gluing ability of plywood produced with DMDHEU-modified veneers of Fagus sp., Betula sp., and Picea sp. Int. J. Adhes. Adhes. 29:206–209.10.1016/j.ijadhadh.2008.05.001Search in Google Scholar

Diouf, P.N, Stevanovic, T., Cloutier, A., Fang, C.H., Blanchet, P., Koubaa, A., Mariotti, N. (2011) Effects of thermo-hygro-mechanical densification on the surface characteristics of trembling aspen and hybrid poplar wood veneers. Applied Surface Sci. 257:3558–3564.10.1016/j.apsusc.2010.11.074Search in Google Scholar

Ermeydan, M.A., Cabane, E., Masic, A., Koetz, J., Burgert, I. (2012) Flavonoid insertion into cell walls improves wood properties. ACS Appl. Mater. Interfaces. 4:5782–5789.10.1021/am301266kSearch in Google Scholar PubMed

Esteves, B., Pereira, H.M. (2009) Wood modification by heat treatment: a review. Bioresources 4:370–404.10.15376/biores.4.1.EstevesSearch in Google Scholar

Grinins, J., Andersons, B., Biziks, V., Andersone, I., Dobele, G. (2013) Analytical pyrolysis as an instrument to study the chemical transformations of hydrothermally modified wood. J. Anal. Appl. Pyrol. 103:36–41.10.1016/j.jaap.2012.10.016Search in Google Scholar

Gusse, A.C., Miller, P.D., Volk, T.J. (2006) White-rot fungi demonstrate first biodegradation of phenolic resin. Environ. Sci. Technol. 40:4196–4199.10.1021/es060408hSearch in Google Scholar PubMed

Herrera, R., Erdocia, X., Llano-Ponte, R., Labidi, J. (2014) Characterization of hydrothermally treated wood in relation to changes on its chemical composition and physical properties. J. Anal. Appl. Pyrol. 107:256–266.10.1016/j.jaap.2014.03.010Search in Google Scholar

Hon, D.N.-S., Shiraishi, N. Wood and Cellulosic Chemistry, Second Edition, Revised and Expanded. Edited by CRC Press, Marcel Dekker Inc., New York, Basel, 2000.10.1201/9781482269741Search in Google Scholar

Irbe, I., Elisashvili, V., Asatiani, M.D., Janberga, A., Andersone, I., Andersons, B., Biziks, V., Grinins, J. (2014) Lignocellulolytic activity of Coniophora puteana and Trametes versicolor in fermentation of wheat bran and decay of hydrothermally modified hardwoods. Int. Biodeter. Biodegr. 86:71–78.10.1016/j.ibiod.2013.06.027Search in Google Scholar

Kocaefe, D., Poncsak, S., Boluk, Y. (2008) Effect of thermal treatment on the chemical composition and mechanical properties of birch and aspen. Bioresources 3:517–537.Search in Google Scholar

Korkut, S., Mehmet, A., Turker, D. (2008) The effects of heat treatment on some technological properties of Scots pine (Pinus sylvestris L.) wood. Bioresource Technol. 99:1861–1868.10.1016/j.biortech.2007.03.038Search in Google Scholar PubMed

Meile, K., Zhurinsh, A., Spince, B. (2014) Aspects of periodate oxidation of carbohydrates for the analysis of pyrolysis liquids. J. Carbohyd. Chem. 33:105–116.10.1080/07328303.2014.885035Search in Google Scholar

Militz, H. (2002) Heat treatment of wood: european processes and their background. The International Research Group on Wood Protection. Document No. IRG/WP 02-4024.Search in Google Scholar

Nuopponen, M., Vuorinen, T., Jämsä, S., Viitaniemi, P. (2004) Thermal modification of softwood studied by FT-IR and UV resonance Raman spectroscopies. J. Wood Chem. Technol. 24:13–26.10.1081/WCT-120035941Search in Google Scholar

Pecina, H., Paprzycki, O. (1988) Wechselbeziehungen zwischen der Temperaturbehandlung des Holzes und seiner Benetzbarkeit. Holzforsch. Holzverw. 40:5–8.Search in Google Scholar

Scouse, A., Kamke, F.A., Morrell, J.J. (2015) Potential for using essential oils to protect viscoelastic thermal compression–treated hybrid poplar. Forest Prod. J. 65:93–99.10.13073/FPJ-D-14-00078Search in Google Scholar

Sundqvist, B., Morén, T. (2002). The influence of wood polymers and extractives on wood colour induced by hydrothermal treatment. Holz Roh-Werkst. 60:375–376.10.1007/s00107-002-0320-2Search in Google Scholar

Tjeerdsma, B., Boonstra, M., Pizzi, A., Tekely, P., Militz, H. (1998) Characterisation of thermally modified wood: Molecular reasons for wood performance improvement. Holz Roh-Werkst. 56:149–153.10.1007/s001070050287Search in Google Scholar

Trey, S.M., Netrval, J., Berglund, L., Johansson, M. (2010) Electron-beam-initiated polymerization of poly(ethylene glycol)-based wood impregnants. ACS Appl. Mater. Interfaces 2:3352–3362.10.1021/am100778qSearch in Google Scholar PubMed

Welzbacher, C.R., Brischke, C., Rapp, A.O. (2007) Influence of treatment temperature and duration on selected biological, mechanical, physical and optical properties of thermally modified timber. Wood Mater. Sci. Eng. 2:66–76.10.1080/17480270701770606Search in Google Scholar

Welzbacher, C.R., Wehsener, J., Rapp, A.O., Haller, P. (2008) Thermo-mechanical densification combined with thermal modification of Norway spruce (Picea abies Karst) in industrial scale-Dimensional stability and durability aspects. Holz Roh-Werkst. 66:39–49.10.1007/s00107-007-0198-0Search in Google Scholar

Wikberg, H., Maunu, S. (2004) Characterisation of thermally modified hard- and softwoods by 13C CPMAS NMR. Carbohyd. Polym. 58:461–466.10.1016/j.carbpol.2004.08.008Search in Google Scholar

Yildiz, S., Gezer, E.D., Yildiz, U.C. (2006) Mechanical and chemical behaviour of spruce wood modified by heat. Build. Environ. 41:1762–1766.10.1016/j.buildenv.2005.07.017Search in Google Scholar

Zaman, A., Alén, R., Kotilainen, R. (2000) Heat behavior of Pinus sylvestris and Betula pendula at 200°C–230°C. Wood Fiber Sci. 32(2): 138–143.Search in Google Scholar

Received: 2015-7-10
Accepted: 2015-12-10
Published Online: 2016-1-28
Published in Print: 2016-8-1

©2016 Walter de Gruyter GmbH, Berlin/Boston

Downloaded on 5.6.2023 from
Scroll to top button