Effect of Extraction on Wood Density of Western Hemlock (<i>Tsuga Heterophylla</i> (RAF.) SARG.)

Authors

  • Ryan Singleton
  • Dean S. DeBell
  • Barbara L. Gartner

Keywords:

Western hemlock, <i>Tsuga heterophylla</i>, extraction, wood density, X-ray densitometry

Abstract

Extractives can account for between 1 to 20% of the oven-dry weight of wood of various tree species and can influence wood density values appreciably. Removing these chemical deposits (extraction) in wood samples can help establish a consistent baseline for comparing wood densities where extractives are expected to differ between sample parameters. Although western hemlock is a very important timber species in the Pacific Northwest, laboratories that determine wood density may or may not remove extractives prior to density assessment. Wood density values were compared before and after extraction for 19 young-growth western hemlock samples. Extraction was performed using 95% ethyl alcohol-toluene solutions. Ring density values averaged 0.045 g/cm3 lower for extracted samples compared to unextracted samples across rings. Slightly higher amounts of extractives were found at rings near the pith; however, a general consistency in extractive content existed among samples and along the radial profile.

References

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Published

2007-06-05

Issue

Number 3 / July 2003

Section

Research Contributions

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