Open Access Open Access  Restricted Access Subscription or Fee Access

Density profile and micromorphology variation of densified wood from three fast growth hardwood species in Costa Rica

Carolina Tenorio, Roger Moya, Mario Tommasiello


This study evaluates 1) the effect of the thermo-hydro-mechanical densification process-using three temperatures, two compression times, and the presence or absence of steam, and 2) the effect of initial wood micromorphology on the density profile of densified wood of three low-density fast growing hardwood species in Costa Rica (Alnus acuminateVochysia ferruginea, and Vochysia guatemalensis). Four density profiles in the densified wood of the three species resulted from the densification temperature and the initial micromorphology of the wood. The initial diameter of the vessels affects the compression stage during the densification process and causes the formation of irregular density profiles. Therefore, this is the most important element in determining the type of the density profile. The wood of A. Acuminata (with smaller-diameter vessels) densified at 180oC tends to produce more uniform density profiles than the other two species that have larger diameter vessels. The time of compression and the use or not of steam as an initial stage in the densification process did not influence the types of density profiles obtained. Similarly, the type of wood tissue and wood pattern had no effect on the type of density profiles. In conclusion, uniform and regular density profiles in densified wood are more likely to be achieve at high temperatures and with smaller-diameter vessels. 



THM densification, vessels, temperature, tropical species

Full Text:



ASTM (2016) Standard test methods for direct moisture content measurement of wood and wood-based materials. Annual Book ASTM Standard. American Society for Testing and Materials, West Conshohocken, PA. 410 pp.

Bao M, Huang X, Jiang M, Yu W, Yu Y (2017) Effect of thermo-hydro-mechanical densification on microstructure and properties of poplar wood (Populus tomentosa). J Wood Sci 63:591-605.

Blomberg J, Persson B (2004) Plastic deformation in small clear pieces of Scots pine (Pinus sylvestris) during den- sification with the CaLignum process. J Wood Sci 50: 307-314.

Darwis A, Wahyudi I, Dwianto W, Cahyono TD (2017) Densified wood anatomical structure and the effect of heat treatment on the recovery of set. J Ind Acad Wood Sci 14: 24-31.

Dwianto W, Morooka T, Norimoto M, Kitajima T (1999) Stress relaxation of sugi (Cryptomeria japonica D. Don) wood in radial compression under high temperature steam. Holzforschung 53:541-546.

Esteves B, Marques AV, Domingos I, Pereira H (2007) Influence of steam heating on the properties of pine (Pinus pinaster) and eucalypt (Eucalyptus globulus) wood. Wood Sci Technol 41:193-207.

Fang C-H, Mariotti N, Cloutier A, Koubaa A, Blanchent P (2012) Densification of wood veneers by compression combined with heat and steam. Eur J Wood Wood Prod 70: 155-163.

Fratzl P, Weinkamer R (2007) Nature’s hierarchical materials. Prog Mater Sci 52:1263-1334.

Gibson LJ (2012) The hierarchical structure and mechanics of plant materials. J R Soc Interface 9:2749-2766.

Huang X, Kocaefe D, Kocaefe Y, Boluk Y, Pichette A (2012) Study of the degradation behavior of heat-treated jack pine (Pinus banksiana) under artificial sunlight irradiation. Polym Degrad Stabil 97:1197-1214.

Jacquin P, Longuetaud F, Leban J-M, Mothe F (2017) X-ray microdensitometry of wood: A review of existing principles and devices. Dendrochronologia 42:42-50.

Kutnar A, Kamke FA, Sernek M (2009) Density profile and morphology of viscoelastic thermal compressed wood. Wood Sci Technol 43:57-68.

Laine K, Segerholm K, Walinder M, Rautkari L, Ormon- droyd G, Hughes M, Jones D (2014) Micromorphological studies of surface densified wood. J Mater Sci 49: 2027-2034.

Metsa-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 als Roh-Werkst 64:192-197.

Moya R (2018) La produccion de madera de especies nativas en plantaciones comerciales: Una opcio n real. Ambientico 267:32-36.

Moya R, Tenorio C, Salas J, Muñoz F, Berrocal A (2019) Tecnologıa de la madera de plantaciones forestales. Editorial Tecnolo´ gica de Costa Rica, 1ra edition. Editorial Tecnologica, Cartago, Costa Rica.

Navi P, Heger F (2004) Combined densification and thermo- hydro-mechanical processing of wood. MRS Bull 29: 332-336.

Rautkari L, Kamke FA, Hughes M (2011a) Density profile relation to hardness of viscoelastic thermal compressed (VTC) wood composite. Wood Sci Technol 45:693-705.

Rautkari L, Laine K, Kutnar A, Medved S, Hughes M (2013) Hardness and density profile of surface densified and thermally modified Scots pine in relation to degree of densification. J Mater Sci 48:2370-2375.

Rautkari L, Laine K, Laflin N, Hughes M (2011b) Surface modification of Scots pine: The effect of process parameters on the through thickness density profile. J Mater Sci 46:4780-4786.

Sandberg D, Haller P, Navi P (2013) Thermo-hydro and thermo-hydro-mechanical wood processing: An opportunity for future environmentally friendly wood products. Wood Mater Sci Eng 8:64-88.

Tenorio C, Moya R (2021) Development of a thermo-hydro- mechanical device for wood densification adaptable to universal testing machines and its evaluation in a tropical species. J Test Eval 49:20180760.

Tenorio C, Moya R, Salas C, Berrocal A (2016) Eval- uation of wood properties from six native species of forest plantations in Costa Rica. Bosque (Valdivia) 37.

Wang JY, Cooper PA (2005) Effect of grain orientation and surface wetting on vertical density profiles of thermally compressed fir and spruce. Holz als Roh-Werkst 63: 397-402.


  • There are currently no refbacks.