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    Author(s): Kristin C. Schad; Daniel L. Schmoldt; Robert J. Ross
    Date: 1996
    Source: USDA Forest Service Research Paper FPL-RP-546. 13 pp.
    Publication Series: Research Paper (RP)
    Station: Forest Products Laboratory
    PDF: View PDF  (1157 KB)


    Wood degradation and defects, such as voids and knots, affect the quality and processing time of lumber. The ability to detect internal defects in the log can save mills time and processing costs. In this study, we investigated three nondestructive evaluation techniques for detecting internal wood defects. Sound wave transmission, x-ray computed tomography, and impulse radar were used to examine white spruce and balsam fir logs. Computed tomography resulted in the highest resolution for voids, knots, and high moisture content areas, but at a very high price. Both sound wave transmission and impulse radar were able to detect large voids and areas of degradation, and these techniques showed some sensitivity to very knotty logs. None of the methods was able to detect small pockets of decay. The use of radar requires an experienced operator because of the difficulty of interpreting the data.

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    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Schad, Kristin C.; Schmoldt, Daniel L.; Ross, Robert J. 1996. Nondestructive Methods for Detecting Defects in Softwood Logs. USDA Forest Service Research Paper FPL-RP-546. 13 pp.


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