• Alena Párničanová Technical university in Zvolen, Slovakia
  • Martin Zachar Technical university in Zvolen, Slovakia
  • Danica Kačíková Technical university in Zvolen, Slovakia
  • Lucia Zacharová National Forest Centre, Forest Research Institute, Slovakia


thermal loading, oak wood, charring rate, charred layer


This paper deals with the determination of selected fire properties of oak wood, i.e., charring rate, which is used in practice to model and investigate the fire causes. Thermal loading was carried out using a measuring apparatus described in Utility Model No. 9373 registered by the Industrial Property Office of the Slovak Republic. Oak wood samples with dimensions of 40 × 50 × 50 mm (l × w × t) were thermally loaded by a heat flux of 15, 20, 25 and 30 kW·m-2, using a ceramic infrared heater. Two methods of determination of the charring rate, based on reaching the temperature of 300 ⁰C in individual depths in a specific time and according to the thickness of the charred layer formed in a time interval of 1800 s measured using a caliper were compared. Both methods confirmed that the charring rate is increasing with increasing thermal loading. The charring rate determined based on the temperature of 300 ⁰C ranged from 0.65 to 0.88 mm·min-1. According to the second method, the charring rate reached values from 0.41 to 0.86 mm·min-1. More accurate results were achieved by applying the method of determination of the charring rate based on the charred layer measured by a caliper. However, the method of determination of the charring rate using thermocouples can be considered less subjective because the temperature is measured automatically, using thermocouples compared to manual measurement using a caliper. The obtained results can be used as input data for computer-supported modeling of indoor fires.


Booth, H., 1987. Carbonisation processes. How wood is transformed into charcoal. The FAO Technical Papers. ISBN 92-5-101328-1.

Blass, H. J., 1995. Timber engineering: STEP 1: Basis of design, material properties, structural components and joints. Almere : Centrum Hout, 1995. 300 p.

Cachim, P. B., Franssen, J. F., 2008. Comparison between the charring rate model and the conductive model of Eurocode 5. In Wiley International Science, (33): 129–143.

Chen, T., Wu, W., Wu, J., Cai, J., Wu, J., 2016. Determination of the pseudocomponents and kinetic analysis of selected combustible solid wastes pyrolysis based on Weibull model. J. Therm. Anal. Calorim, (126): 1899–1909.

Findorák, R., Fröhlichová, M., Legemza, J., Findorákova, L., 2016. Thermal degradation and kinetic study of sawdusts and walnut shells via thermal analysis. J. Therm. Anal. Calorim, (125): 689–694.

Friquin, K. L., 2011. Material properties and external factors influencing the charring rate of solid wood and glue-laminated timber. In Wiley Online Library, 35(5): 303–327.

Gašpercová, S., Wesserle, F., 2021. Influence of flame burning on different types of wooden prisms. Technical University in Žilina.

Hasburgh, R. H., Dietenberg, M. A., 2001. Wood Products. In Thermal Degradation and Fire.

Hrovatin, J., 2005. Contemporary systems of prefabricated wooden house construction. Wood in the Construction Industry: Durability and Quality of Wooden Construction Products. Proceedings Paper, 21-26. ISBN 953-6307-80-4.

Kačíková D, Makovická-Osvaldová L., 2009. Wood burning rate of various tree parts from selected softwoods. Acta Fac. Xylologiae. 2009;51: 27–32. ISSN 1336−3824.

Kamenická, Z., Sandanus, J., Blesák, L., Cábová, K., Waldt, F., 2018. Methods for determing the charring rate of timber and their mutual comparison. Wood research, 63(4): 583-590.

Kravetz, C., Leca, C., Brito, J. O., Saloni, D., and Tilotta, DC., 2020. Characterization of selected pyrolysis products of diseased orange wood. BioResources, 15(3): 7118-7126.

Liu, C, Deng, Y, Wu, S, Lei, M, Liang, J., 2016. Experimental and theoretical analysis of the pyrolysis mechanism of a dimeric lignin model compound with α-O-4 linkage. BioResouces, 11(2): 3626-3636.

Martinka, J., Rantuch, P., Liner, M., 2018. Calculation of charring rate and char depth of spruce and pine wood from mass loss. Journal Thermal Analysis Calorimetry (132): 1105–1113.

Mikkola, E., 2007. Charring of Wood Based Materials. Fire safety science. 2007. s. 10. eISBN 9780203973493

NFPA 921; Guide for Fire and Explosion Investigations; National Fire Protection Association: Quincy, MA, USA, 2021.

Njankouo, J. M., Dotreppe, J. C., Franssen, J. M., 2004. Experimental study of the charring rate of tropical hardwoods. Fire and materials, 28(15):

Qin, R.; Zhou, A.; Chow, C.L.; Lau, D., 2021. Structural performance and charring of loaded wood under fire. Eng. Struct, (228): 111491.

Požgaj, A., Chovanec, D., Kurjatko, S., Babiak, M., 1997. Structure and properties of wood. Bratislava: Príroda, a.s., ISBN 80-07-00960-4.

Richter, F.; Atreya, A.; Kotsovinos, P.; Rein, G., 2019. The effect of chemical composition on the charring of wood across scales. Proc. Combust. Inst, (37): 4053–4061.

Salmen, L., Olsson, A. M., Stevanic, JS., Simonovic, J. Radotic, K., 2011. Structural organisation of tha wood polymers in the wood fibre structure. Proceedings Paper. 2011. s. 7-12. WOS: 000394407800002

Špilák, D., Tereňová, Ľ., Dúbravská, K., Majlingová, A., 2018. Analysis of the charred layer of wooden beams with different geometric cross-section shapes. Delta, 12(2): 65-81.

Wen, L., Han, L., Zhou, H., 2015. Factors Influencing the Charring Rate of Chinese Wood by using the Cone Calorimeter. BioResources 10, 7263-7272.

White, R.H.; Nordheim, E.V., 1992. Charring rate of wood for ASTM E 119 exposure. Fire Technol, (28): 5–30.

Xu, M., Tu, L., Cui, Z., Chen, Z., 2020. Charring properties and temperature profiles of laminated bamboo under single side of ISO 834 fire exposure. BioResources, (15): 1445-1462. /biores.15.1.1445-1462

Zachar, M., Čabalová, I., Kačíková, D., Zacharová, L., 2021. The Effect of Heat Flux to the Fire-Technical and Chemical Properties of Spruce Wood (Picea abies L.). Materials (Basel) 14, 4989.

Zanatta, P., Peres, M. L., Gallio, E., Ribes, D. D., Lazarotto, M., Gatto, D. A., Moreira, M. L., 2018. Reduction of flammability of Pinus elliottii wood modified with TiO2 particles, Matéria (Rio de Janeiro), (23):




How to Cite

Párničanová, A., Zachar, M., Kačíková, D., & Zacharová, L. (2023). DETERMINATION OF CHARRING RATE OF OAK WOOD. Acta Facultatis Xylologiae Zvolen, 65(2), 25–34. Retrieved from