Time-Course Changes of Chemical and Physical Properties in Sugi (<i>Cryptomeria Japonica</i> D. Don) Logs During Smoke Heating


  • Futoshi Ishiguri
  • Mihoko Matsui
  • Minoru Andoh
  • Shinso Yokota
  • Nobuo Yoshizawa


Sugi, smoke heating


Kiln-drying of sugi (Japanese cedar, Cryptomeria japonica D. Don) wood is a very difficult process. This is because the moisture content (MC) of the green log is very high and varies considerably between heartwood and sapwood. To investigate the time-course changes of chemical and physical properties during smoke heating, sugi green logs were smoke-heated with different treatment times at a temperature inside the log of 80°C using a modified food smoker. After smoke heating, the amounts of chemical components and some physical properties, such as MC, relative degree of crystallinity (RDC), equilibrium moisture content (EMC), and bending strength, were examined. The distribution of MC within the log became uniform after smoke heating for 60 h. Almost no differences in the amounts of chemical components were recognized between the control and smoke-heated woods. The relative degree of crystallinity increased with smoke heating for 40 h, corresponding to the decrease in EMC. The modulus of elasticity (MOE) in static bending increased with smoke heating, whereas the modulus of rupture and the absorbed energy in impact bending did not change significantly. The increase in MOE was considered to be due to the increase in RDC. The results obtained here indicated that no significant thermal degradation of wood occurred by smoke heating for 60 h at a temperature inside the log of 80°C. However, smoke heating affected the physical properties, such as RDC, EMC, and MOE.


Andoh, M., N. Takahashi, and N. Yoshizawa. 1996. Rupture of pit membranes and quality improvement in sugi logs by smoke-heating system with increased radiation of far-infrared rays. Mokuzai Gakkaishi42:845-853.nDavis, W. H., and W. S. Thompson. 1964. Influence of thermal treatments of short duration on the toughness and chemical composition of wood. Forest Prod. J.15(2):350-356.nDwiant, W., M. Inoue, and M. Norimoto. 1997. Fixation of compressive deformation of wood by heat treatment. Mokuzai Gakkaishi43:303-309.nFujita, S. 1994. Fibril angle. Pages 130-133 in T. Furuno and O. Sawabe, eds. Mokuzai Kagaku Kouza 2. Soshiki to Zaishitsu. Kaiseisha, Ohtsu.nHillis, W. E. 1984. High temperature and chemical effects on wood stability Part 1: General considerations. Wood Sci. Technol.18:281-293.nHirai, N., N. Sobue, and I. Asano. 1972. Studies on piezoelectric effect of wood IV. Effects of heat treatment on cellulose crystallities and piezoelectric effect of wood. Mokuzai Gakkaishi18:535-542.nInoue, M., and M. Norimoto. 1991. Permanent fixation of compressive deformation in wood by heat treatment. Wood Res. Tech. Notes27:31-40.nIshiguri, F., M. Andoh, S. Yokota, and N. Yoshizawa. 1998. Wood quality of sugi (Cryptomeria japonica D. Don) by smoke-heating with increased far-infrared radiation. J. Soc. Mat. Sci. Japan47:361-367.nIshiguri, F., K. Saitoh, M. Andoh, Z. Abe, S. Yokota, and N, Yoshizawa. 2000. Improvement of heartwood color in black-colored sugi (Cryptomeria japonica D. Don) by UV irradiation after smoke heating. Holzforschung54:294-300.nKadita, S., T. Yamada, M. Suzuki, and K. Komatsu. 1961. Studies on rheological properties of wood. II. Effect of heat-treating condition on the hygroscopicity and dynamic Young's modulus of wood. Mokuzai Gakkaishi7:34-38.nKitahara, K., and M. Chuganji. 1951. Effects of heat treatment on the mechanical properties of wood. J. Japan Forest Soc.33:414-419.nKubojima, Y., T. Okano, and M. Ohta. 1998. Vibrational properties of sitka spruce heat treated in nitrogen gas. J. Wood Sci.44:73-77.nNomura, T. 1995. Smoke-dry heat treatment of wood -on the central topic of sugi wood-. Wood Res Tech Notes31:31-43.nOkauchi, S., K. Hayashi, H. Yamamoto, and Y. Kanagawa. 1997. Kouon shitsunetsu shori niyoru mokuzai no zaishitsu henka. Abst. 47th Anu. Mtg. Japan Wood Res. Soc., p. 164.nOkuyama, T. 1996. Kunen netsusyori no tokushitsu nitsuite. Abst. 1996th Nihon Mokuzai Gakkai Mokuzai to Mizu Kenkyukai Symposium, pp. 6-9.nOkuyama, T., Y. Kanagawa, and Y. Hattori. 1987. Reduction of residual stresses in logs by direct heating method. Mokuzai Gakkaishi33:837-843.nOkuyama, T., T., H. Yamamoto, and Y. Murase. 1988. Quality improvement in small sugi by direct heating method. Wood Industry43:359-363.nOkuyama, T., T., H. Yamamoto, and I. Kobayashi. 1990. Quality improvement in small sugi by direct heating method (2). Wood Industry45:63-67.nSegal, L., J. J. Creely, A. E. Martin Jr., and G. M. Gonrad. 1959. An empirical method for estimating the degree of crystallinity of native cellulose using the X-ray diffractometer. Text. Res. J.29:786-794.nTAPPI. 1991. Tappi test methods, vol. I T1-T270. Tappi press, Atlanta, GA.nTejada, A., T. Okuyama, H. Yamamoto, and M. Yoshida. 1997. Reduction of growth stress in logs by direct heat treatment: Assessment of a commercial-scale operation. Forest Prod. J.47(9):86-93.nThompson, W. S. 1969. Effect of steaming and kiln drying on the properties of southern pine poles, Part II: Chemical properties. Forest Prod. J.19(2):37-42.nYoshizawa, N., M. Andoh, F. Ishiguri, S. Yokota, and T. Furuno. 1999. Rupture of pit membranes in sugi (Cryptomeria japonica D. Don) logs by a smoke-heating system with increased far-infrared radiation. Holzforschung53:9-15.n






Research Contributions