Maximum Effective Pit Pore Radii Of The Heartwood And Sapwood Of Six Softwoods As Affected By Drying And Resoaking
Abstract
Air pressures were determined that will just displace water or water containing a wetting agent from the void structure of cross sections of green sapwood and heartwood of six different softwoods varying in thickness from 1/32 inch to 3 inches. Measurements were again made on the same specimens after air- and oven-drying and resaturating with water or water containing a wetting-agent solution. Maximum effective radii of the openings were calculated from these pressures and the surface tensions of the liquids. Maximum lumen radii and maximum fiber lengths were obtained from the linear plots of the pore radii against the thickness of the specimens in the thin-specimen range. Both were greater for sapwood than for heartwood. Maximum effective pit pore radii were obtained for passage through 50 pits in series from the linear plots of the logarithm of the effective pit pore radius against the logarithm of the number of pits traversed in series. These values were used to show relative differences in calculated permeabilities between sapwood and heartwood, which varied greatly between species, and to show the effect of drying with and without a wetting agent present. Wetting agents tend to prevent loss in permeability on drying, presumably by reducing the drying tension on the pit membranes, thus avoiding aspiration, at least in the pit membranes containing the larger pores.References
Comstock, G. L. 1965. Longitudinal permeability of green eastern hemlock. Forest Prod. J., 15(10): 441-449.nComstock, G. L. 1967. Longitudinal permeability of wood to gases and nonswelling liquids. Forest Prod. J., 17(10): 41-46.nComstock, G. L. 1968. Relationship between the permeability of green and dry eastern hemlock. Forest Prod. J., 18(18): 20-23.nGriffin, G. L. 1919. Bordered pits in Douglas-fir: a study of the position of the torus in mountain and lowland specimens in relation to creosote penetration. J. Forestry, 17: 813-822.nHart, C. A., And R. J. Thomas. 1967. Mechanism of bordered pit aspiration as caused by capillarity. Forest Prod. J., 17(11): 61-68.nLiese, W., and J. Bauch. 1967. On the closure of bordered pits in conifers. Wood Sci. and Tech., 1(1): 1-13.nResch, H., and D. G. Arganbright. 1968. Variation of specific gravity, extractive content, and tracheid length in redwood trees. Forest Science, 14(2): 148-155.nStamm, A. J. 1963. Permeability of wood to fluids. Forest Prod. J., 13(10): 503-507.nStamm, A. J. 1964. Wood and cellulose science. Ronald Press Co., N.Y. 405 p.nStamm, A. J. 1966. Maximum pore diameter of film materials. Forest Prod. J., 16(12): 59-63.nStamm, A. J. 1967. Flow of fluids in wood, Part I. Wood Sci. and Tech., 1(2): 122-141.nStamm, A. J., and D. G. Arganbright. 1970. Surface tension of the sap of several species of wood. Wood and Fiber (In press).nStamm, A. J., S. W. Clary, and W. J. Elliott. 1968. Effective radii of lumen and pit pores in softwoods. Wood Science, 1(2): 94-101.nThomas, R. J., and D. D. Nicholas. 1966. Pit membrane structure in loblolly pine as influenced by solvent exchange drying. Forest Prod. J., 16(3): 53-56.nZuidemn, H. H., and G. W. Waters. 1941. Correction factor for surface and interfacial tension by ring method. Ind. Eng. Chem., Anal. Ed., 13: 312.n
Downloads
Published
Issue
Section
License
The copyright of an article published in Wood and Fiber Science is transferred to the Society of Wood Science and Technology (for U. S. Government employees: to the extent transferable), effective if and when the article is accepted for publication. This transfer grants the Society of Wood Science and Technology permission to republish all or any part of the article in any form, e.g., reprints for sale, microfiche, proceedings, etc. However, the authors reserve the following as set forth in the Copyright Law:
1. All proprietary rights other than copyright, such as patent rights.
2. The right to grant or refuse permission to third parties to republish all or part of the article or translations thereof. In the case of whole articles, such third parties must obtain Society of Wood Science and Technology written permission as well. However, the Society may grant rights with respect to Journal issues as a whole.
3. The right to use all or part of this article in future works of their own, such as lectures, press releases, reviews, text books, or reprint books.
