A newly developed thermo-hydro treatment (THT) for use in a one-stage heat treatment process was examined by focusing on the form stability-related properties of European aspen (Populus tremula), birch silver (Betula pendula), and gray alder (Alnus incana). In particular, wood specimens were subjected to THT in a saturated steam atmosphere in a pilot-scale autoclave heated between 140 and 180°C for 1–3 h. Several parameters of untreated and treated samples after several soaking and drying cycles were compared, namely, the changes in the volumetric swelling, swelling in the radial and tangential directions, cell wall total water capacity, and anti-swelling efficiency (ASE). Due to repeated wetting in the cyclic water submersion-drying test, the original ASE of 73% decreased to 65% (180°C for 1 h), and the original ASE of 33% decreased to 5% (140°C for 1 h). Wood modified at 170°C presented good results that were not significantly lower than wood treated at higher temperatures while consuming less energy to deliver ASE improvement and was selected as optimum. To increase the ASE by 1%, the amount of energy consumed was decreased by 41%, 39%, and 17% compared with the treatment regimes of 160°C for 1 h, 160°C for 3 h, and 180°C for 1 h, respectively. The new THT regime led to improved long-term dimensional stability due to the cross-linking of cell wall polymers, which resulted in increased cell wall rigidity.
Boonstra, M.J., Tjeerdsma, B.F., Groeneveld, H.A.C. (1998) Thermal modification of nondurable wood species. 1. The PLATO technology; thermal modification of wood. The International Research Group on Wood Preservation, Doc. No. IRG/WP/98-40123.
Bourgois, J., Bartholin, M., Guyonnet, R. (1989) Thermal treatment of wood: analysis of obtained product. Wood Sci. Technol. 23:303–310.
Bowyer, J.L., Shmulsky, R., Haygreen, J.G. (2003) Forest Products and Wood Science: An Introduction. 4th ed. Blackwell Publishing Professional, Iowa, US.
Browning, B.L. (1967) Methods of Wood Chemistry. Vol. 1., Wiley, New York.
Burmester, A. (1973) Einfluss einer Wärme-Druck-Behandlung halbtrockenen Holzes auf seine Formbeständigkeit. Holz Roh-Werkst. 31:237–243.
Chaouch, M., Dumarçay, S., Pétrissans, A., Pétrissans, M., Gérardin, P. (2013) Effect of heat treatment intensity on some conferred properties of different European softwood and hardwood species. Wood Sci. Technol. 47:663–673.
Dirol, D., Guyonnet, R. (1993) The improvement of wood durability by rectification process. The International Research Group on Wood Preservation, Doc. No. IRG/WP 93-40015.
Esteves, B., Domingos, I., Pereira, H. (2007a) Improvement of technological quality of eucalypt wood by heat treatment in air at 170-200C. For. Prod. J. 57:47–52.
Esteves, B., Velez Marques, A., Domingos, I., Pereira, H. (2007b) Influence of steam heating on the properties of pine (Pinus pinaster) and eucalypt (Eucalyptus globulus) wood. Wood. Sci. Technol. 41:193–207.
Esteves, B., Velez Marques, A., Domingos, I., Pereira, H. (2007b) Influence of steam heating on the properties of pine (Pinus pinaster) and eucalypt (Eucalyptus globulus) wood. Wood. Sci. Technol. 41:193–207.10.1007/s00226-006-0099-0)| false
Ibbett, R.N., Kaenthong, S., Phillips, D.A.S., Wilding, M.A. (2007) Solution adsorption and exclusion studies of the structure of never-dried and re-wetted cellulosic fibres. J. Mater. Sci. 42:6809–6818.
Kim, G.Y.K., Kim, J. (1998) Effect of heat treatment on the decay resistance and the bending properties of radiata pine sapwood. Material und Organismen 32:101–108.
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.
Korkut, S., Akgü, M., Dündar, T. (2008) The effect of heat treatment on some technological properties of Scots pine (Pinus sylvestris L.) wood. Bioresour. Technol. 99:1861–1868.
Metsä-Kortelainen, S., Antikainen, T., Viitaniemi, P. (2006) The water absorption of sapwood and heartwood of Scots pine and Norway spruce heat treated at 170°C, 190°C, 210°C and 230°C. Holz Roh-Werkst. 64:192–197.
Metsä-Kortelainen, S., Antikainen, T., Viitaniemi, P. (2006) The water absorption of sapwood and heartwood of Scots pine and Norway spruce heat treated at 170°C, 190°C, 210°C and 230°C. Holz Roh-Werkst. 64:192–197.10.1007/s00107-005-0063-y)| false
Militz, H, Tjeerdsma B. (2002) Heat treatment of wood by the Plato process. In: Review on Heat Treatments of Wood, Proceedings of the special seminar of COST Action E22, Antibes, France.
Militz, H. (2008) Processes and properties of thermally modified wood manufactured in Europe. ACS Symp. Ser. 982:372–388.
Mohhebby, B., Sanaei, I. (2005) Influences of hydro-thermal treatment on physical properties of beech wood (Fagus orientalis).The International Research Group on Wood Preservation; IRG Document No.: IRG/WP 05-40303.
Ohmae, K., Minato, K., Norimoto, M. (2002) The analysis of dimensional changes due to chemical treatments and water soaking for Hinoki (Chamaecyparis obtuse) wood. Holzforschung 56:98–102.
Ohmae, K., Minato, K., Norimoto, M. (2002) The analysis of dimensional changes due to chemical treatments and water soaking for Hinoki (Chamaecyparis obtuse) wood. Holzforschung 56:98–102.10.1515/HF.2002.016)| false
Rautkari, L., Honkanen, J., Callum, A.S.H., Ridley-Ellis Hughes, M. (2014) Mechanical and physical properties of thermally modified Scots pine wood in high pressure reactor under saturated steam at 120, 150, and 180°C. Eur. J. Wood Prod. 72:33–41.
Rautkari, L., Honkanen, J., Callum, A.S.H., Ridley-Ellis Hughes, M. (2014) Mechanical and physical properties of thermally modified Scots pine wood in high pressure reactor under saturated steam at 120, 150, and 180°C. Eur. J. Wood Prod. 72:33–41.10.1007/s00107-013-0749-5)| false
Usta, I. (2007) Theory of aesthetics – charm in furniture and an aesthetic evaluation of bleaching of natural color of wood through the application of experimental bleaching process. 38th Annual Meeting of the International Group on Wood Protection, Wyoming, USA. Doc. No. IRG/WP 07-30424.
Wang, J., Cooper, P.A. (2005) Effect of oil type, temperature and time on moisture properties of hot oil-treated wood. Holz Roh- Werkst. 63:417–422.
Weiland, J.J., Guyonnet, R. (2003) Study of chemical modifications and fungi degradation of thermally modified wood using DRIFT spectroscopy. Holz Roh-Werkst. 61:216–220.10.1007/s00107-003-0364-y)| false
Welzbacher, C.R., Brischke, C., Rapp, O.R. (2007) Influence of treatment temperature and duration on selected biological, mechanical, physical and optical properties of thermally modified timber. Wood Mat. Sci. Eng. 2:66–76.
Willems, W. (2009) A novel economic large scale production technology for high quality thermally modified wood. Stockholm, Sweden. 31–35.
Zaman, A., Alén, R., Kotilainen, R. (2000) Heat behaviour of Pinus sylvestris and Betula pendula at 200–230°C. Wood Fiber Sci. 32:138–143.