• Gabriela Slabejová Technical University in Zvolen
  • Zuzana Vidholdová Technical University in Zvolen
  • Mária Šmidriaková Technical University in Zvolen


birch, colour, maple, surface finish, hydrothermally modified wood


The paper deals with the influence of ageing in the dark and in the light on the colour of a transparent surface finish. In the experiments, Paper birch (Betula papyrifera Marsh) and Norway maple wood (Acer pseudoplatanus L.) were hydrothermally treated at 135 °C under saturated water vapour for 6 hours. The colour parameters were measured after native wood and thermally treated wood were surface finished. Three different types of surface finishes (acrylic-polyurethane, polyacrylic and aldehyde resin, and alkyd resin) were applied on the wood surfaces. The colour parameters of the tested surfaces (system CIE L*a*b*, chroma C*, hue angle h°) were measured immediately after surface finishing and ageing. The tested samples were aged either in the dark or in the sunlight behind windows glass, in the interior, for 60 days. The results showed that the colour of the wood and the colour of surface finishes changed after ageing in the dark and the light. The changes were different. The surfaces mostly lighten up in the dark and darken in the light.


Bulian, F.; Graystone, J.A. 2009. Wood Coatings—Theory and Practice; Elsevier: Amsterdam, The Netherlands.

Cirule, D.; Sansonetti, E.; Andersone, I.; Kuka, E.; Andersons, B. 2021.Enhancing thermally modified wood stability against discoloration. Coatings, 11, 81.

Decker, C., Zahouily, K. 1999. Photodegradation and photooxidation of thermoset and UV-cured acrylate polymers. Polymer Degradation and Stability, 64(2), 293–304,

Dudiak, M.; Dzurenda, L. 2021. Changes in the physical and chemical properties of alder wood in the process of thermal treatment with saturated water steam. Coatings, 11, 898.

Dudiak, M. 2021. Modification of maple wood colour during the process of thermal treatment with saturated water steam. Acta Fac. Xylologiae Zvolen, 63, 25–34.

Durmaz, S., Özgenç, Ö., Avci, E., Boyaci, I.H. 2020. Weathering performance of waterborne acrylic coating systems on flat‐pressed wood–plastic composites. J. Appl. Polym. Sci., 137, 48518,

Dzurenda, L., Dudiak, M. 2020. Changes in wood tree species Fagus sylvatica L. and characteristics of the thermal process of modifying its color with saturated water steam. Appl. Ecol. Environ. Res., 5, 142–156.

Dzurenda, L., Geffert, A., Geffertová, J., Dudiak, M. 2020. Evaluation of the process thermal treatment of maple wood saturated water steam in terms of change of pH and color of wood. BioRes., 15, 2550–2559.

Geffert, A., Geffertová, J., Výbohová, E., Dudiak, M. 2020. Impact of steaming mode on chemical characteristics and color of birch wood. Forests, 11, 478.

Herrera, R., Sandak, J., Robles, E., Krystofiak, T., Labidi, J., 2018. Weathering resistance of thermally modified wood finished with coatings of diverse formulations. Progress in Organic Coatings, 119, 145-154.

Kminiak, R., Orlowski, K.A., Dzurenda, L., Chuchala, D., Banski, A. 2020. Effect of thermal treatment of birch wood by saturated water vapor on granulometric composition of chips from sawing and milling processes from the point of view of its processing to composites. App. Sci., 10.21: 7545.

Kučerová V., Lagaňa R., Hýrošová T. 2019. Changes in chemical and optical properties of silver fir (Abies alba L.) wood due to thermal treatment. J Wood Sci, 65, 1–10.

Kúdela, J., Sikora, A., Svocák, J. 2020. Colour stability of spruce wood surface coated with a polyurethane lacquer without and with a UV absorber admixture. In XIII: Konference Pigmenty a Pojiva: sbornik/Conference Preceedings; Chemagazín: Pardubice, Czech Republic, pp. 28–30, ISBN 978-80-906269-5-9.

Kúdela, J. 2017. Accelerated ageing-induced effects on surface properties of wood veneers treated with a modified water-based coating system. Ann. WULS-SGGW, For. and Wood Technol, 98, 59–65.

Lee S.H., Ashaari Z., Lum W.C., Halip J.A., Ang A.F., Tan L.P., Chin K.L., Tahir, P.M. 2018. Thermal treatment of wood using vegetable oils: A review. Constr Build Mater, 181, 408−419.

Liu, R., Zhu, H., Li, K., Yang, Z. 2019. Comparison on the aging of woods exposed to natural sunlight and artificial Xenon Light. Polymers, 11, 709.

Miklecic, J., Jirouš-Rajković, V., Antonović, A., Španić, N. 2011. Discolouration of thermally modified wood during simulated indoor sunlight exposure. BioResources, 6, 434–446.

Nowrouzi, Z., Mohebby, B., Ebrahimi, M. Petrič, M., 2021. Effects of different additives in a waterborne polyacrylate coating on selected surface properties of heat-treated finished wood. Drewno: prace naukowe, doniesienia, komunikaty, 64.

Pandeley, K.K. 2005. Study of the effect of photo-irradiation on the surface chemistry of wood. Polym. Degrad. Stab., 90, 9–20.

Peng, Y., Wang, Y., Chen, P., Wang, W. Cao, J., 2020. Enhancing weathering resistance of wood by using bark extractives as natural photostabilizers in polyurethane-acrylate coating. Progress in Organic Coatings, 145, p.105665.

Reinprecht L., Vidholdová Z. 2011. Thermowood. Šmíra – Print, s.r.o.: Ostrava, Czech Republic, 89.

Reinprecht, L., Tiňo, R., Šomšák, M. 2020. The impact of fungicides, plasma, UV-additives and weathering on the adhesion strength of acrylic and alkyd coatings to the Norway spruce wood. Coatings, 10, 1111.

Ruiz, F.J., Agell, N., Angulo, C., Sánchez, M., 2012. A qualitative learning system for human sensory abilities in adjustment tasks. In 26th International workshop on qualitative reasoningAt: Playa Vista, California, Estados Unidos de América.

Salcă, E.A., Cismaru, I. 2011. Colour changes evaluation of freshly cut alder veneers under the influence of indoor sunlight. Pro Ligno, 7, 15–24.

Salla, J., Pandey, K.K., Srinivas, K. 2012. Improvement of UV resistance of wood surfaces by using ZnO nanoparticles. Polym. Degrad. Stab., 97, 592–596,

Sandberg D., Kutnar A., Mantanis G. 2017. Wood modification technologies-a review. IForest, 10, 895−908.

Sandberg, D., Kutnar, A., Karlsson, O., Jones, D. 2021. Wood Modification Technologies: Principles, Sustainability, and the Need for Inno-vation, 1st ed.; CRC Press, Taylor and Francis Ltd.: Abingdon, UK, 450p; ISBN 978-1-138-49177-9.

Sedliačiková, M., Aláč, P., Moresová, M. Sedliačik, I., 2021. Mapping the wood colour preferences among potential customers. Acta Facultatis Xylologiae Zvolen res Publica Slovaca, 63(2), pp.163-173. 10.17423/afx.2021.63.2.14

Slabejová, G.; Šmidriaková, M. 2020. Colour of thermally modified wood finished with transparent coatings. Trieskové a beztrieskové obrábanie dreva (Chip and Chipless Woodworking Processes), 12, 97–102.

Solár, R. 1997. Lignin Changes in Hydrothermal Wood Treatment Processes, 1st ed.; Technical University in Zvolen: Zvolen, Slovakia, p. 57.

Šimůnková, K., Pánek, M. Zeidler, A., 2018. Comparison of selected properties of shellac varnish for restoration and polyurethane varnish for reconstruction of historical artefacts. Coatings, 8(4), p.119.

Timar, M.C., Varodi, A.M, Hacibektasoglu, M., Campean, M. 2016. Color and FT-IR analysis of chemical changes in beech wood (Fagus sylvatica L.) after light steaming and heat treatment in two different environments. BioResources, 11, 8325–8343.

Tolvaj, L., Mitsui, K. 2010. Correlation between hue angle and lightness of light irradiated wood. Polym. Degrad. Stab., 95, 638–642.

Vidholdová, Z., Sandak, A., Sandak, J. 2019. Assessment of the chemical change in heat treated pine wood by near infrared spectroscopy. Acta Fac. Xylologiae Zvolen, 61, 31–42.




How to Cite

Slabejová, G., Vidholdová, Z., & Šmidriaková, M. (2023). CHANGE IN THE COLOUR OF TRANSPARENT SURFACE FINISH ON HYDROTHERMALLY TREATED WOOD . Acta Facultatis Xylologiae Zvolen, 65(1), 45–56. Retrieved from