Surface carbonization of wood: comparison of the biological performance of Pinus taeda and Eucalyptus bosistoana woods modified by contact charring method

ABSTRACT

This study evaluated biological resistance, water absorption, and total carbohydrate contents of carbonized woods by contact charring method followed by linseed oil submersion. Charred and control specimens were exposed in laboratory fungal resistance tests to two white – and two brown-rot fungi and in mold resistance tests by spraying the surface with a mold spore-suspension comprised of three different mold species. Charred and control specimens were also evaluated for resistance to the eastern subterranean termites. To help understand biological durability results, carbohydrate content and water absorption of test specimens were also determined. In all cases, durability against wood degrading fungi increased with the exception of charred Eucalyptus bosistoana wood exposing to the white-rot fungus, Irpex lacteus. Mold resistance of charred Pinus taeda specimens increased considerably when compared to controls however, no mold growth was observed on either control or charred specimens of E. bosistoana. In termite tests, significantly less weight losses were shown in charred specimens of both wood species tested compared to controls although, no complete protection was achieved against termite attack. Total carbohydrate content of charred wood specimens decreased after the carbonization process and as expected, increased hydrophobicity was observed with >50% less water uptake in charred specimens.

KEYWORDS:

• Durability
• charred wood
• fungi
• termites
• mold

Acknowledgements

The authors acknowledge Amy Bishell of USDA FS Forest Products Laboratory (FPL), Madison, WI, USA for help with specimen preparation for chemical analysis and termite resistance tests and Carlos Baez of USDA FS FPL, Madison, WI, USA for performing total carbohydrate content analyses. All authors contributed to the conceptualization and methodology of the study. Material preparation was performed by CMI, data collection and analysis were performed by SNK, EES, RAA, KMO, CMI, ES, and IÇ. The first draft of the manuscript was written by SNK, and RAA and all authors commented on subsequent versions of the manuscript. All authors read and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data used for this work are available from the corresponding author upon reasonable request.