Influence of temperature of thermal treatment on surface densification of spruce

Research output: Contribution to journalArticleScientificpeer-review


Research units

  • University of Ljubljana
  • Oregon State University
  • University of Primorska


Spruce (Picea abies L. Karst) wood lamellae, thermally treated at 170, 190, 210 and 230 °C were surface densified by compression at a temperature of 150 °C to three degrees of compression. Immediate springback, set recovery, mechanical properties in 3-point flexure, Brinell hardness and density profiles measurements were used to determine the effect of thermal treatment on the properties of surface densified wood. The highest immediate springback occurred in wood specimens thermally treated at the highest temperature (230 °C) and decreased with decreasing thermal treatment temperature. The untreated samples had the highest set recovery, which decreased with the temperature of thermal treatment. The surface densification increased hardness and bending strength. The highest increase was in the case of untreated wood and decreased with the temperature of thermal treatment. The modulus of elasticity (MOE) and modulus of rupture (MOR) of surface densified wood decreased with increasing thermal treatment temperature. The trend was similar for specimens which were thermally treated but not surface densified. Surface densification increased the density of the specimens in the first few millimetres below the surface. The highest density was achieved in untreated specimens and the lowest in specimens thermally treated at the highest temperature.


Original languageEnglish
Pages (from-to)113-123
Number of pages11
JournalEuropean Journal of Wood and Wood Products
Issue number1
Early online date12 May 2016
Publication statusPublished - Jan 2017
MoE publication typeA1 Journal article-refereed

ID: 4300001