The Uniformity Factor-a Proposed Method for Expressing Variations in Specific Gravity


  • James R. Olson
  • Donald G. Arganbright


<i>Pseudotsuga menziesii</i>, <i>Abies concolor</i>, specific gravity, X-ray densitometry, densitometry, wood quality, physical properties


Existing measures of uniformity of specific gravity, as obtained by X-ray densitometry, are examined in light of how well they fulfill the requirements thought to be necessary for a uniformity indicator. Based upon an examination of mass and volume specific gravity distributions, a new indicator is proposed. This indicator, the uniformity factor, relates the volume distribution of specific gravity within an increment of wood to a selected reference base. The suitability of the uniformity factor for estimating wood uniformity is shown using data from two species of different uniformities. This approach appears to have potential as a new tool in predicting wood quality.


Echols, R. M. 1972a. Product suitability of wood … determined by density gradients across growth rings. USDA For. Serv. Res. Note PSW-273.nEchols, R. M. 1972b. Patterns of wood density distribution and growth rate in Ponderosa pine. Pp. H1-H16. Proc. Symp. on Effect of Growth Acceleration on Properties of Wood, Madison, WI, Nov. 1971.nEchols, R. M. 1973. Uniformity of wood density assessed from X-rays of increment cores. Wood Sci. Technol, 7(1):34-44.nLarson, P. R. 1969. Wood formation and the concept of wood quality. Yale Univ. Sch. For. Bull. No. 74.nMegraw, R. A. 1975. Personal communication.nMegraw, R. A., and W. P. Munk. 1974. Effect of fertilization and thinning on wood density of young coastal Douglas-fir. Pp. 85-91. Proc. 1974 Forest Biology Conf., Seattle, Wash.nMeyer, R. W. 1977. Personal communication.nMitchell, H. L. 1961. A concept of intrinsic wood quality, and nondestructive methods for determining quality in standing timber. U.S. For. Prod. Lab. Rep. No. 2233.nOlson, J. R. 1974. Uniformity of specific gravity and other physical properties: a criterion for evaluating wood quality. Unpubl. M.S. thesis. Univ. of Calif., Berkeley.nParker, M. L., and R. W. Kennedy. 1973. The status of radiation densitometry for measurement of wood specific gravity. Proc. 1973 IUFRO-5 Mtg., Republ. S. Afr. 2:882-893.nPolge, H. 1965. Study of wood density variations by densitometric analysis of X-ray negatives of samples taken with a Pressler auger. Proc. 1965 IUFRO-Section 41 Mtg., Melbourne, Aust.n






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