Effect of Extractives on Moisture Sorption and Shrinkage in Tropical Woods


  • Elvin T. Choong
  • Suminar S. Achmadi


Extractives, desorption, adsorption, shrinkage, moisture, tropical woods, fiber saturation point


Samples of sixteen tropical wood species from Indonesia were selected to undergo desorption and adsorption in the unextracted and extracted form. The anisotropic shrinkage values of these samples were also determined. At high humidities, the extracted woods exhibit higher equilibrium moisture contents than the unextracted woods. However, the isotherms of extracted and unextracted woods coincide at relative humidities below 70% for both desorption and adsorption. This phenomenon indicates that the hygroscopicity of wood is affected at high humidities through the extractives bulking the amorphous region in the cell wall. The shrinkage intersection point ranges from 18.0 to 34.1%, with an average of 24.8%, which is below the predicted 30% for temperate-zone woods. The linear relationship between volumetric shrinkage and specific gravity was significant, but the correlation (r2 = 0.40) is quite low. The removal of extractives with hot water and organic solvents caused excessive shrinkage. All the woods tested showed partial collapse, indicating the plasticization of the extractives at high temperature and high moisture content in the cell wall structure.


Chafe, S. C. 1987. Collapse, volumetric shrinkage, specific gravity and extractives in Eucalyptus and other species. Part 2. The influence of wood extractives. Wood Sci. Technol. 21:27-41.nChen, P. Y. S. 1975. The effect of steaming time and temperature on the longitudinal permeability of black walnut. Wood Fiber 7:222-225.nChoong, E. T. 1969. Effect of extractives on shrinkage and other hygroscopic properties of ten southern pine woods. Wood Fiber 1:124-133.nChoong, E. T., and S. Achmadi. 1989. Effect of steaming and hot-water extraction on the longitudinal permeability of several Indonesian woods. J. For. Res. Dev. 5(2):33-36 (text in Indonesian with English summary).nChoong, E. T., and F. G. Manwiller. 1976. Dimensional and relative hygroscopic properties of hardwoods from southern pine sites. Wood Sci. 9:39-43.nChoong, E. T., J. F. G. MacKay, and C. M. Stewart. 1973. Collapse and moisture flow in kiln drying and freeze drying of woods. Wood Sci. 6:127-125.nChoong, E. T., P. J. Fogg, and C. B. Pollock. 1989. Variation in shrinkage properties of second-growth baldcypress and tupelo-gum. Wood Fiber Sci. 21:17-29.nChristensen, G. N., and K. E. Kelsey. 1958. The sorption of water vapor by the constituents of wood: Determination of sorption isotherms. Austr. J. Appl. Sci. 9:265-282.nComstock, G. L. 1965. Longitudinal permeability of green eastern hemlock. For. Prod. J. 15:441-449.nCooper, G. A. 1974. The effect of black walnut extractives on sorption, shrinkage, and swelling. Wood Sci. 6:380-388.nDemaree, L. A., and R. W. Erickson. 1976. Temperature-dependent effect of extractive content on redwood shrinkage. Wood Sci. 8:227-283.nEllwood, E. L., and B. A. Ecklund. 1961. Treatments to improve wood permeability as an approach to the drying problems. Proc. 13th Ann. Mtg. of West Coast Kiln Clubs, Medford, OR.nEllwood, E. L., and R. W. Erickson. 1962. Effect of presteaming on seasoning stain and drying rate of redwood. For. Prod. J. 12:328-332.nFogg, P. J. 1968. Longitudinal air permeability of southern pine wood. Ph.D. dissertation, Louisiana State Univ., Baton Rouge, LA.nKanagawa, Y., and Y. Hattori. 1984. Physical properties of Sulawesi woods. Bull. Nagoya Forests No. 8, Nagoya Univ., Nagoya. (Text in Japanese with English summary)nKinninmonth, J. A. 1971. Effect of steaming on the fine structure of Nothofagus Fusca. New Zealand J. For. Sci. 1:129-139.nKinninmonth, J. A. 1973. Permeability and fine structure of certain hardwoods and effect on drying. Holzforschung 27:127-133.nKelsey, K. E. 1956. The shrinkage intersection point—Its significance and the method of its determination. For. Prod. J. 6:411-417.nKubinsky, E. 1971. Influence of steaming on the properties of Quercus rubraL. Holzforschung 25:78-83.nNarayanamurti, D. 1957. The role of extractives in wood. Holz Roh Werkst. 15:370-380.nNearn, W. T. 1955. Effect of water soluble extractives on the volumetric shrinkage and equilibrium moisture content of eleven tropical and domestic woods. Pennsylvania State Univ. Agr. Exp. Sta. Bull. 598, University Park, PA.nNicholas, D. D., and R. J. Thomas. 1967. The influence of enzymes on the structure and permeability of loblolly pine. In Proc. Am. Wood Pres. Assoc. 68:70-76.nNicholas, D. D., and R. J. Thomas. 1968. Influence of steaming on ultrastructure of bordered pit membrane in loblolly pine. For. Prod. J. 18:57-59.nOkoh, K. I. A. 1976. Moisture sorption and electrical resistivity of some woods and barks. Ph.D. dissertation, State Univ. New York, Coll. Environ. Sci., Syracuse, NY.nOkoh, K. I. A., and C. Skaar. 1980. Moisture sorption isotherms of the wood and innerbark of ten southern U.S. hardwoods. Wood Fiber 12:98-111.nSimpson, W. T. 1975. Effect of steaming on the drying rate of several species of wood. Wood Sci. 7:247-255.nSkaar, C. 1972. Water in wood. Syracuse Univ. Press., Syracuse, NY.nSkaar, C. 1988. Wood-water relations. Springer-Verlag, NY.nSmith, D. 1955. A comparison of two methods for determining the specific gravity of small samples of second-growth Douglas-fir. Rept. 2033, USDA Forest Prod. Lab., Madison, WI.nSpalt, H. A. 1957. The sorption of water vapor by domestic and tropical woods. For. Prod. J. 7:331-335.nSpalt, H. A. 1958. The fundamentals of water vapor sorption by wood. For. Prod. J. 8:228-295.nSpalt, H. A. 1979. Water-vapor sorption by woods of high extractive content. Pages 55-61 in Proc. Wood moisture content—Temperature and humidity relationships. Virginia Polytech. Inst. and State Univ., Blacksburg, VA, October 29, 1979.nStamm, A. J. 1964. Wood and cellulose science. The Ronald Press Co., NY.nTaylor, F. W. 1974. Effect of extraction on the volume dimensions and specific gravity of solid wood blocks. Wood Sci. 6:396-404.nTambunan, B., S. Setiati, and E. T. Choong. 1975. Hugroscopicity of some Indonesian woods. Kehutanan Indonesia. Bogor, Indonesia. Pages 796-800, (Text in Indonesian with English summary.)nUrquhart, A. R., and N. Eckersall. 1930. The moisture relations of cotton: A study of hysteresis. J. Textile Inst. 21:T499.nWangaard, F. F., and L. A. Granados. 1967. The effect of extractives on water-vapor sorption by wood. Wood Sci. Technol. 1:253-277.n






Research Contributions