Natural weathering performance of thermally treated poplar and black pine wood


  • Vasiliki Kamperidou
  • Ioannis Barboutis


Colour, pine, poplar, surface roughness, thermal modification, weathering


Wood of poplar (Populus sp.) and black pine (Pinus nigra) species was subjected to thermal treatment under variant conditions of temperature, 180 ºC and 200 ºC, and duration of 3 h, 5 h, 7 h, and its resistance to natural weathering was investigated through the determination of crucial properties, such as the colour and surface roughness, while the appearance of the boards was assessed both visually and through a microscope, prior to and after their exposure outdoors. Prior to the outdoors exposure, it was observed that, as the intensity of heat treatment increases, wood tends to darken, with the parallel decrease of L* index, referring to tangential, radial and cross-sectional surface of both species specimens. The surface roughness of both wood species was found decreased only in the boards of the mildest treatment, while as the treatment intensity increases, the roughness degree demonstrated a strong increase compared to unmodified wood. After the 100-day exposure of poplar and pine boards to external conditions, they acquired a wilder look and new checks and cracks emerged in the boards surface, while fungi infestation signs appeared, most apparent in control and boards treated at milder treatments, with modified poplar boards to demonstrate more dense defects patterns on their surfaces, compared to modified black pine boards. A similar degree of discoloration recorded on unmodified boards was observed also on the thermally modified boards, which was except for the visual assessment, confirmed by the recorded progress of L*, a* and b* colour indexes of poplar and pine surfaces and is probably attributed to leaching of the water soluble extractives. The roughness of all of the exposed boards surfaces was found higher than the respective values recorded prior to the exposure and among the treated boards only those of the milder treatments presented lower roughness values than the unmodified ones. Thermal treatment enhanced the biological durability and dimensional stability of both species, but it did not adequately protect wood from the weathering effect when it was exposed outdoors. Nevertheless, wood modified at short-term heat treatments exhibited enhanced properties compared to unmodified wood and taking into account that the milder treatments did not cause mechanical strength loss, these materials could be utilized in applications where structures are not continually and directly exposed to aging factors, such as under shelter applications, or after the application of a thermal and surface modification with protective preservatives combination.


Download data is not yet available.


American Society for Testing and Materials. 2016. ASTM D2244 – 16: Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates. ASTM International. West Conshohocken, PA, USA.

Ates, S.; Akyildiz, M.H.; Özdemir, H.; Gumuskaya, E. 2010. Technological and chemical properties of chestnut (Castanea sativa Mill.) wood after heat treatment. Rom Biotechnol Lett 15(1): 4949-4958.

Awoyemi, L.; Jarvis, M.C.; Hapca, A. 2009. Effects of preboiling on the acidity and strength properties of heat-treated wood. Wood Sci Technol 43: 97–103.

Bak, M.; Nemeth, R. 2012. Changes in swelling properties and moisture uptake rate of oil-heat-treated poplar (Populus × euramericana cv. Pannónia) wood. BioResources 7(4): 5128-5137.

Budakci, M.; Cemil Ilce, A.; Gurleyen, T.; Utar, M. 2013. Determination of the surface roughness of Heat-treated wood materials planed by the cutters of the horizontal milling machine. BioResources 8(3): 3189-3199.

DIN. Deutsches Institut für Normung. 1998. DIN EN ISO 4288:1998-04: Determination of surface roughness values of the parameters r[a], r[z], r[max] by means of electrical contact (stylus) instruments; terminology, measuring conditions. Berlin, Germany.

DIN. Deutsches Institut für Normung. 2012. DIN EN ISO 11664-3: Colorimetry - Part 3: CIE tristimulus values. Berlin, Germany.

CEN, European Committee for Standardisation. 2019. EN 927-3: Paints and varnishes. Coating materials and coating systems for exterior wood. Natural weathering test. Brussels, Belgium.

Feist, C.W.; Sell, J. 1987. Weathering behavior of dimensionally stabilized wood treated by heating under pressure of nitrogen gas. Wood Sci Technol 19(2): 183-195.

Garcia, R.A.; Lopes, J.; do Nascimento, A.M.; Latorraca J.V. 2014. Color stability of weathered heat-treated teak wood. Maderas-Cienc Tecnol 16(4): 453–462.

Gündüz, G.; Korkut, S.; Korkut, D.S. 2008. The effects of heat treatment on physical and technological properties and surface roughness of Camiyanı Black Pine (Pinus nigra Arn. subsp. pallasiana var. pallasiana) wood. Bioresour Technol 99: 2275-2280.

Hill, C. 2006. Wood Modification, Chemical, Thermal and other processes. John Wiley & Sons Ltd, The Átreium, Southern Gate, Chichester, UK.

ISO, International Organization for Standardization. 2014. ISO 13061-1: Physical and Mechanical Properties of Wood-Test Methods for Small Clear Wood Specimens—Part 1: Determination of Moisture Content for Physical and Mechanical Tests. Geneva, Switzerland.

ISO, International Organization for Standardization. 2014. ISO 13061-2: Physical and Mechanical Properties of Wood-Test Methods for Small ClearWood Specimens - Part 2: Determination of Density For Physical and Mechanical Tests. ISO: Geneva, Switzerland.

ISO, International Organization for Standardization, 2019. ISO 3129: Wood - Sampling Methods and General Requirements for Physical And Mechanical Testing of Small Clear Wood Specimens. Geneva, Switzerland.

ISO, International Organization for Standardization. 1997. ISO 4287: Geometrical Product Specifications (GPS) - Surface texture: Profile method -Terms, definitions and surface texture parameters. Geneva, Switzerland.

ISO, International Organization for Standardization. 2016. ISO 4628-1: Paints and varnishes - Evaluation of degradation of coatings - Designation of quantity and size of defects, and of intensity of uniform changes in appearance - Part 1: General introduction and designation system. Geneva, Switzerland.

Kamperidou, V.; Barboutis, I. 2017. Mechanical Performance of Thermally Modified Black Pine (Pinus nigra L.) Wood. Electron. J Pol Agric Univ 20: 7–13.

Kamperidou, V.; Barboutis, I. 2018. Changes in hygroscopic properties of poplar and black pine induced by thermal treatment. PRO Ligno 14(4): 57–64.

Kamperidou, V.; Barboutis, I.; Vasileiou, V. 2013. Hygroscopicity of thermally modified poplar (Populus sp.) wood. PRO Ligno 9(4): 664-669.

Kamperidou, V. 2019. The biological durability of thermally- and chemically-modified black pine and poplar wood against basidiomycetes and mold action. Forests 10(12): 1111.

Korkut, S.; Budakci, M. 2010. The effects of high-temperature heat-treatment on physical properties and surface roughness of Rowan (Sorbus aucuparia L.) wood. Wood Research 55(1): 67-78.

Mburu, F.; Dumarcay, S.; Bocquet, J.F.; Petrissans, M.; Gerardin, P. 2008. Effect of chemical modifications caused by heat treatment on mechanical properties of Grevillea robusta wood. Polym Degrad Stabil 93(2): 401-405.

Mummery, L. 1992. Surface texture analysis. The handbook. Hommelwerke, Muhlhausen, Germany. 106p.

Rajković, V.J.; Miklečić, J. 2012. New insights into improving the colour stability of thermally modified wood exposed to UV-light. In International Conference of Ambienta 2012, Zagreb, Croatia.

Sandberg, D. 1999. Weathering of radial and tangential wood surfaces of pine and spruce. Holzforschung 53(4): 355-364.

Schneid, E.; de Cademartori, P.H.G.; Gatto, D. 2014. The effect of thermal treatment on physical and mechanical properties of Luehea divaricata hardwood. Maderas-Cienc Tecnol 16 (4): 413-422.

Stumbo, D.A. 1963. Surface texture, measuring methods. Forest Prod J 12(7): 299-303.

Yildiz, S.; Yildiz, U.; Tomak, E. 2011. The effects of natural weathering on the properties of heat-treated alder wood. BioResources 6(3): 2504-2521.




How to Cite

Kamperidou, V. ., & Barboutis, I. . (2021). Natural weathering performance of thermally treated poplar and black pine wood. Maderas-Cienc Tecnol, 23, 1–12. Retrieved from




Most read articles by the same author(s)