European Journal of Wood and Wood Products

, Volume 72, Issue 6, pp 785–797 | Cite as

Colour in short-term thermo-mechanically densified veneer of various wood species

  • Pavlo Bekhta
  • Stanisław Proszyk
  • Tomasz Krystofiak


Effect of short-term thermo-mechanical (STTM) densification temperature and pressure on the surface colour of veneer of four wood species—alder (Alnus glutinosa Gaertn.), beech (Fagus sylvatica L.), birch (Betula verrucosa Ehrh.), and pine (Pinus sylvestris L.) as well as possible correlations among all determined colour parameters (L*, a*, b*, h, C* and ∆E) were investigated. Veneer sheets were densified at temperatures of 100, 150 or 200 °C and pressures of 4, 8 or 12 MPa for 4 min. The results were compared with those of non-densified veneers. The colour change of the samples was evaluated by CIEL*a*b* and L*h*C* colour co-ordinate systems. The results indicated: the temperature and pressure of densification affected to a big extent the colour of the veneer samples, with the effect of densification temperature being more evident than that of pressure. After the densification process, the veneers darkened. Colour changes are most pronounced at the highest densification temperature of 200 °C and very small at the lower temperatures of 100 and 150 °C for all investigated wood species. The change in a* is more pronounced than the change in L* or b*. In general, alder and birch veneer samples are characterized by the highest values of total colour difference followed by pine and beech samples among the four species. The quadratic models can be used for the prediction of surface colour in the densification process. The results of this study indicate that it is possible to govern surface colouration of wood veneers during densification process on an industrial basis.


Wood Species Wood Surface Colour Parameter Surface Colour Total Colour Difference 
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 would like to thank the COST Action FP 1006 “Bringing new functions to wood through surface modification” for financial support within the frame of Short Term Scientific Mission (STSM).


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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Pavlo Bekhta
    • 1
  • Stanisław Proszyk
    • 2
  • Tomasz Krystofiak
    • 2
  1. 1.Department of Wood-Based CompositesNational University of Forestry and Wood Technology of UkraineLvivUkraine
  2. 2.Department of Gluing and Finishing of WoodPoznan University of Life SciencesPoznanPoland

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