Journal of Materials Science

, Volume 48, Issue 24, pp 8571–8579 | Cite as

Anatomical properties and process parameters affecting blister/blow formation in densified European aspen and downy birch sapwood boards by thermo-hygro-mechanical compression

  • Sheikh Ali AhmedEmail author
  • Tom Morén
  • Olle Hagman
  • Alain Cloutier
  • Chang-Hua Fang
  • Diego Elustondo


Approximately, 13.5 % of the standing volume of productive forest land in Sweden is covered by birch and aspen, which provides the vast potential to produce value-added products such as densified wood. This study shows whether it is possible to densify those species with a thermo-hygro-mechanical (THM) process using heat, steam, and pressure. In this process, transverse compression on thin European aspen (Populus tremula) and downy birch (Betula pubescens) boards was performed at 200 °C with a maximum steam pressure of 550 kPa. To obtain a theoretical 50 % compression set, the press’s maximum hydraulic pressure ranged from 1.5 to 7.3 MPa. Preliminary tests showed that ~75 % of the birch boards produced defects (blisters/blows) while only 25 % of the aspen boards did. Mainly, radial delamination associated with internal checks in intrawall and transwall fractures caused small cracks (termed blisters) while blows are characterized by relatively larger areas of delamination visible as a bumpy surface on the panel. Anatomical investigations revealed that birch was more prone to those defects than aspen. However, those defects could be minimized by increasing the pre-treatment time during the THM processing.

Graphical Abstract


Fiber Length Densified Wood Anatomical Property Transverse Compression Vessel Frequency 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



The authors acknowledge the European Union and the European Regional Development Fund, the County Administration of Västerbotten, the Municipality of Skellefteå, and TräCentrum Norr for their financial support. Special thanks are also extended to Birger Marklund, Technician, Luleå University of Technology, Campus Skellefteå for helping with sample preparation and the Centre de Recherche sur le Bois (CRB), Département des Sciences du Bois et de la Forêt, Université Laval, Québec, QC, Canada for THM processing.


  1. 1.
    Skogsstyrelsen (2012) Swedish statistical yearbook of forestry. Swedish Forest Agency, Jönköping, Sweden, pp. 380 (ISSN 0491-7847, ISBN 978-91-88462-97-8)Google Scholar
  2. 2.
    Kutnar A, Kamke FA, Sernek M (2008) Holz Roh Werkst 66:439CrossRefGoogle Scholar
  3. 3.
    Kutnar A, Kamke FA, Sernek M (2009) Wood Sci Technol 43:57CrossRefGoogle Scholar
  4. 4.
    Fang C-H, Mariotti N, Cloutier A, Koubaa A, Blanchet P (2012) Eur J Wood Prod 70:155CrossRefGoogle Scholar
  5. 5.
    Kunesh RH (1961) For Prod J 11:395Google Scholar
  6. 6.
    Tabarsa T, Chui YH (1997) For Prod J 47:85Google Scholar
  7. 7.
    Tabarsa T, Chui YH (2000) Wood Fiber Sci 32:144Google Scholar
  8. 8.
    Navi P, Girardet F (2000) Holzforschung 54:287CrossRefGoogle Scholar
  9. 9.
    Kamke FA (2006) Maderas 8:83Google Scholar
  10. 10.
    Zhou C, Smith GD, Dai C (2009) Holzforschung 63:609CrossRefGoogle Scholar
  11. 11.
    Navi P, Heger F (2004) MRS Bull 29:332CrossRefGoogle Scholar
  12. 12.
    Schwarze FWMR, Spycher M (2005) Holzforschung 59:358CrossRefGoogle Scholar
  13. 13.
    Skyba O, Niemz P, Schwarze FWMR (2009) Holzforschung 63:639CrossRefGoogle Scholar
  14. 14.
    Bodig J (1965) For Prod J 15:197Google Scholar
  15. 15.
    Easterling KE, Harrysson R, Gibson LJ, Ashby MF (1982) Proc R Soc Lond A 383:31CrossRefGoogle Scholar
  16. 16.
    Nairn JA (2006) Wood Fiber Sci 38:576Google Scholar
  17. 17.
    Fukuta S, Takasu Y, Sasaki Y, Hirashima Y (2007) Wood Fiber Sci 39:548Google Scholar
  18. 18.
    Dogu D, Tirak K, Candan Z, Unsal O (2010) BioResources 5:2640Google Scholar
  19. 19.
    Wang JY, Cooper PA (2005) Holz Roh Werkst 63:39Google Scholar
  20. 20.
    Wang BJ, Dai C (2005) Holzforschung 59:10Google Scholar
  21. 21.
    Abramoff MD, Magalhaes PJ, Ram SJ (2004) Biophotonics Int 11:36Google Scholar
  22. 22.
    Franklin GL (1945) Nature 155:51CrossRefGoogle Scholar
  23. 23.
    Sperry JS, Hacke UG (2004) Am J Bot 91:369CrossRefGoogle Scholar
  24. 24.
    Hacke UG, Sperry JS, Pittermann J (2004) Am J Bot 91:386CrossRefGoogle Scholar
  25. 25.
    Courtney TH (2000) Mechanical behaviour of materials. McGraw-Hill, BostonGoogle Scholar
  26. 26.
    Tabarsa T, Chui YH (2001) Wood Fiber Sci 33:223Google Scholar
  27. 27.
    Ellis S, Steiner P (2002) IAWA J 23:201CrossRefGoogle Scholar
  28. 28.
    Thomas RJ (1976) Wood Fiber 7:256Google Scholar
  29. 29.
    Wheeler EA, Thomas RJ (1981) Wood Fiber 13:169Google Scholar
  30. 30.
    Côté WA (1963) J Polymer Sci C2:231Google Scholar
  31. 31.
    Behr EA, Sachs IB, Kukachkaa BF, Blew JL (1969) For Prod J 19:31Google Scholar
  32. 32.
    Booker RE, Kininmonth JA (1978) NZ J For Sci 8:295Google Scholar
  33. 33.
    Keey RB, Langrish TAG, Walker JCF (2000) Kiln-drying of lumber. Springer-Verlag, BerlinCrossRefGoogle Scholar
  34. 34.
    Beery WH, Ifju G, McLain TE (1983) Wood Fiber Sci 15:395Google Scholar
  35. 35.
    Hart CA (1984) For Prod J 34:45Google Scholar
  36. 36.
    Blomberg J, Persson B (2005) J Wood Sci 50:307Google Scholar

Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  • Sheikh Ali Ahmed
    • 1
    Email author
  • Tom Morén
    • 1
  • Olle Hagman
    • 2
  • Alain Cloutier
    • 3
  • Chang-Hua Fang
    • 3
  • Diego Elustondo
    • 1
  1. 1.Department of Engineering Sciences and Mathematics, Division of Wood Science and Engineering, Wood PhysicsLuleå University of TechnologySkellefteaSweden
  2. 2.Department of Engineering Sciences and Mathematics, Division of Wood Science and Engineering, Wood Products EngineeringLuleå University of TechnologySkellefteaSweden
  3. 3.Wood Research Center (CRB), Department of Wood and Forest Sciences, Faculty of Forestry, Geography and GeomaticsLaval UniversityQuebecCanada

Personalised recommendations