Air permeability of thermally modified hemlock wood

Plinska permeabilnost termično modificiranega lesa zahodne čuge


  • Yaohui Liu Department of Wood Science, Faculty of Forestry, University of British Columbia
  • Stavros Avramidis Department of Wood Science, Faculty of Forestry, University of British Columbia



wood, thermal modification, western hemlock, longitudinal air permeability, specific permeability, temperature effect


Western hemlock (Tsuga heterophylla) is a prevalent coastal species in British Columbia (BC). Its wood has a high potential for thermal modification, a process that can affect numerous physical properties, including air permeability. The current study investigates the longitudinal air permeability of hemlock wood modified at three temperature levels, 170 °C, 212 °C, and 230 °C, and a two-hour treatment length. Permeability values obtained using Darcy’s law and the water-falling volume displacement method were positively correlated with treatment temperature up to 212 °C, after which the permeability decreased slightly. ANOVA followed by the Duncan test revealed that thermal treatment at 212 °C and 230 °C significantly increased air permeability, whereas it was insignificant at 170 °C.


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Alden, H. (1995). Softwoods of North America, FPL-GTR-102. Madison, WI. U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, 151pp.

Bahmani, M., & Schmidt, O. (2018). Plant essential oils for environment-friendly protection of wood objects against fungi. Maderas. Ciencia y tecnología, 20(3), 325-332. DOI:

Bahmani, M., Schmidt, O., Fathi, L., & Frühwald, A. (2016). Environment-friendly short-term protection of palm wood against mould and rot fungi. Wood Material Science & Engineering, 11(4), 239-247. DOI:

Chu, D., Mu, J., Avramidis, S., Rahimi, S., Liu, S., & Lai, Z. (2019a). Functionalized

surface layer on poplar wood fabricated by fire retardant and thermal densification.

Part 1: compression recovery and flammability. Forests, 10(11), 955.

Chu, D., Mu, J., Avramidis, S., Rahimi, S., Liu, S., & Lai, Z. (2019b). Functionalized surface layer on poplar wood fabricated by fire retardant and thermal densification. Part 2: dynamic wettability and bonding strength. Forests, 10(11), 982. DOI:

Donath, S., Militz, H., & Mai, C. (2006). Creating water-repellent effects on wood by modification with silanes. Holzforschung, 60(1), 40-46. DOI:

Dong, H., Bahmani, M., Rahimi, S., & Humar, M. (2020). Influence of copper and biopolymer/Saqez resin on the properties of poplar wood. Forests, 11(6), 667. DOI:

Esteves, B., & Pereira, H. (2009). Wood modification by heat treatment: A review. BioResources, 4(1), 370-404. DOI:

Hermawan, A., Sakagami, H., Sobri, S. A., Amini, M. H. M., Ramle, S. F. M., & Rasid, S. (2020). The effects of drying temperatures on preservative retention and penetration of some Malaysian fast-growing species timbers. Drying Technology, 39(4), 566-75. DOI:

Hill, C. A. (2006). Wood modification: chemical, thermal, and other processes (Vol. 5). Chichester, John Wiley & Sons, 237 pp. DOI:

Hill, C. A. S., Jones, D., Strickland, G., & Cetin, N. S. (1999). Kinetic and mechanistic aspects of the acetylation of wood with acetic anhydride. Holzforschung, 52(6), 623-629. DOI:

Kang, C. W., Li, C., Jang, E. S., Jang, S. S., & Kang, H. Y. (2018). Changes in sound absorption capability and air permeability of Malas (Homalium foetidum) specimens after high temperature heat treatment. Journal of the Korean Wood Science and Technology, 46(2), 149-54. DOI:

Lin, R.T. & Kozlik, C.J. 1971. Permeability and drying behavior of western hemlock. Proc. 22 nd Annual Meeting Western Dry Kiln Club, pp. 44-50. Oregon State Univer., Corvallis, OR.

Mansouryar, E., Karimi, A., Ebrahimi, G., Mirshokraei, A., & Rahimi, S. (2010). Water repelling Populus Alba by emulsion of paraffin, Quaternary ammonium and hydrated starch. IJWP, 25, 211–222. (In Farsi)

Nourian, S., & Avramidis, S. (2021). Exploratory thermal modification of western hemlock. Wood Material Science & Engineering, 16(4), 221-228. DOI:

Perre, P. (2007). Fundamental Wood Drying. European COST. Nancy, France, 366pp.

Poonia, P. K., Tripathi, S., Sihag, K., & Kumar, S. (2015). Effect of microwave treatment on air permeability and preservative impregnation of Eucalyptus tereticornis wood. Journal of the Indian Academy of Wood Science, 12(2), 89-93. DOI:

Rahimi, S., Singh, K., DeVallance, D., Chu, D., & Bahmani, M. (2022). Drying behavior of hardwood components (sapwood, heartwood, and bark) of red oak and yellow-poplar. Forests, 13(5), 722. DOI:

Rahimi, S., Singh, K, & DeVallance, D. (2019). Effect of different hydrothermal treatments (steam and hot compressed water) on physical properties and drying behavior of yellow poplar (Liriodendron tulipifera). Forest Products Journal, 69, 42-52. DOI:

Rahimi, S., Faezipour, M., & Tarmian, A. (2011). Drying of internal-check prone poplar lumber using three different conventional kiln drying schedules. Journal of the Indian Academy of Wood Science, 8(1), 6-10. DOI:

Rhatigan, R. G., Milota, M. R., Morrell, J. J., & Lavery, M. R. (2003). Effect of high temperature drying on permeability and treatment of western hemlock lumber. Forest products journal, 53.

Rousset, P., Perré, P., & Girard, P. (2004). Modification of mass transfer properties in poplar wood (P. robusta) by a thermal treatment at high temperature. Holz als Roh-und Werkstoff, 62(2), 113-9. DOI:

Siau, J. F. (1995). Wood-Influence of moisture on wood properties. Blacksburg, Va.: Dept. of Wood Science and Forest Products, Virginia Polytechnic Institute and State University.

Taghiyari, H. R., & Malek, B. M. (2014). Effect of heat treatment on longitudinal air and liquid permeability of circular and square-shaped native hardwood specimens. Heat and Mass Transfer, 50(8), 1125-36. DOI:

Ward, J. C., & Pong, W. Y. (1980). Wetwood in trees: a lumber resource problem. USDA Forest Service General Technical Report PNW 112, Pacific North West Forest Range Station, Portland, Oregon, 56pp. DOI:

Yuan, L. (1994). Heat treatment of Eucalyptus wood and its permeability improvement. China Wood Industry, 1994; 8(3), 30-3. (In Chinese).







How to Cite

Liu, Y., & Avramidis, S. (2022). Air permeability of thermally modified hemlock wood: Plinska permeabilnost termično modificiranega lesa zahodne čuge. Les/Wood, 71(2), 25-30.

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