Detecting Compression Wood in Green Loblolly Pine with Radio Frequency

Compression wood is formed on the lower side of leaning softwood trees stem. High density and high microfibril angle lead to a very high longitudinal shrinkage compared to that of normal wood. This shrinkage leads to a high degree of warp and resultant value loss in lumber during drying. Detection of compression wood in green lumber would allow segregation of the lumber for special handling or product designation and reduce value loss from warpage during drying. A dielectric method was tested to differentiate compression from normal wood in green loblolly pine lumber. Compression wood produced a considerable increase in the phase shift of an applied radio frequency signal. A threshold value was determined, tested, and resulted in 95%, 100%,95%, and 80% successful differentiation of compression from normal wood in lumber for 100, 500, 1000 and 5000 kHz frequencies, respectively.


1. T. E. Timell. Compression Wood in Gymnosperms. Vol. 1. Springer-Verlag, Berlin, Heidelberg, Germany (1986).

2. A. J. Panshin, and C. deZeeuw. Textbook of Wood Technology, Vol. 1. McGraw-Hill, Inc., New York, NY. (1970).

3. R. Shmulsky, and P. D. Jones. Forest Products and Wood Science, 6th Ed. The Iowa State University Press, Ames, lowa. (1982).

4. P. Koch. Utilization of the Southern Pines. Vol. 1. U.S. Department of Agriculture-Forest Service, Washington, D.C. (1972).

5. F. G. Wagner and F. W. Taylor. Forest Products Journal 45:59–62 (1994).

6. F. W. Taylor and F. G. Wagner. Forest Products Journal 46:53–56 (1996).

7. C. Anderson and F. Walter. Forest Products Journal 45:87–92 (1995).

8. J. Nystrom and E. Kline. Wood and Fiber Science 32:301–310 (2000).

9. J. Nystrom and O. Hagman. Journal of Wood Science 45:30–37 (1999).

10. J. Johansson, O. Hagman, and J. Oja. Proc. of the Fourth International Conference on Image Processing and Scanning of Wood, Mountain Lake, VA, August 21–23, 2000.

11. R. J. King, and J. C. Basuel. Proc. of the 8th Nondestructive Testing of Wood Symposium. Vancouver, WA. September 23–25, 1991.

12. P. H. Steele, and J. E. Cooper. U.S. Patent No. 6,784,671: Moisture and Density Detector. U.S. Patent Office, Washington, D.C. (2004).

13. American Society for Testing Materials. Standard Test Methods for Direct Moisture Content Measure-ments of Wood and Wood-Based Materials. ASTM D4442–92. ASTM, Philadelphia (1996).

14. American Society for Testing Materials. Standard Test Methods for Specific Gravity of Wood and Wood-Based Materials. ASTM D2395–93. ASTM, Philadelphia (1996).

Usage Shares
Total Views
1 Page Views
Total Shares
0 Tweets
0 PDF Downloads
0 Facebook Shares
Total Usage