Pretreatment with Ultrasonic Energy—Its Effect Upon Volumetric Shrinkage of Redwood
Abstract
Redwood heartwood samples 1.2 inches in cross section were subjected to ultrasonic irradiation prior to oven-drying. There was a small but consistent reduction in volumetric shrinkage due to the pretreatment when the test cell was subjected to continuous vacuum during irradiation. It is believed that cavitation of the wood liquid was responsible for the effect. However, since the sample moisture contents were considerably less than the maximum moisture content for redwood, the effect was evidently due to something other than the elimination of Tiemann liquid tension stress. It is suggested that the denaturing is of the kind, but not to the extent, of that believed to occur in the freezing of wet redwood.References
Erickson, R., J. Haygreen, and R. Hossfeld. 1966. Drying prefrozen redwood—with limited data on other species. Forest Prod. J., 16(8): 57-65.nErickson, R. 1968. Drying of prefrozen redwood—fundamental and applied considerations. Forest Prod. J., 18(6): 49-56.nErickson, R. 1969. Effect of prefreezing upon the hygroscopicity and shrinkage of thin cross sections of California redwood. Forest Prod. J., 19(5): 55-56.nErickson, R., and D. J. Sauer. 1969. Flexural creep behavior of redwood heartwood during drying from the green state. Forest Prod. J., 19(12): 45-51.nGuenther, William G. 1964. Analysis of variance. Chapter three. Prentice-Hall, Inc., Englewood Cliffs, N. J.nJarreau, F. R. 1953. Procede de traitment des bois frais. Forestry Abstract No. 1646 (French patent No. 968,874, May 10, 1950).nMorris, Charles O. 1969. Ultrasonics for wood industries. Report No. E-2 Oregon Forest Research Center, Corvallis, Oregon.nWOOD HANDBOOK. 1955. Agricultural Handbook No. 72. U. S. Government Printing Office, Washington, D. C. p. 77.n
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