Official website of the New Zealand Farm Forestry Association


Scion’s core funded experiments on thermal modification of Eucalyptus nitens.

By Rosie Sargent, Bruce Davy, Elizabeth Dunningham, August 2017.

Download SWP-T021 (pdf)

Executive summary

The objective of this work was to replicate successful lab scale thermal modifications of Eucalyptus nitens at a larger scale. Lab scale thermal modification has been shown to improve dimensional stability and durability of E. nitens while darkening the wood colour. Pilot scale modifications also allow further property testing, such as evaluating the effect of thermal modification on the strength of knots, and allowing more in depth testing of durability and dimensional stability. Lab scale modifications have had excessive levels of between ring checking after modification, and attempts are being made to reduce this.

Key results

Properties of the pilot scale modifications were similar to those of the lab scale, but were often more variable (e.g. Anti shrink efficiency). The strength of knots relative to clear timber was not affected by thermal modification. Dimensional stability in humid air environments is significantly improved by thermal modification at 210°C (185°C was not tested). Between-ring checking was not reduced at the pilot scale, but subsequent lab scale modifications have significantly reduced levels of checking.

Further work

For thermal modification of E. nitens to be successful at a commercial scale, issues of within-charge variability and levels of between-ring checking need to be solved.

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