Wood can be modified by compressive, thermal and chemical treatments. Compression of wood under thermal conditions is resulted in densification of wood. This study evaluated decay and termite resistance of thermally compressed pine wood panels at either 5 or 7 MPa and at either 120 or 150°C for one hour. The process caused increases in density and decreases in thickness of the panels; however, laboratory decay resistance tests using one brown rot fungus and one white rot fungus revealed that thermally compressed wood was not resistance against the fungi tested. More interesting results were found in laboratory termite resistance tests. As pressure and temperature increased up to 7 MPa and 120°C, mass losses in the specimens decreased gradually when compared to control specimens. However, the specimens compressed at 7MPa and 150°C showed higher mass losses in comparison with the specimens compressed at 7 MPa and 120°C. Decay and termite resistance of such materials is still controversial even though density is improved under thermal processing.
Unsal, Oner; Kartal, S. Nami; Candan, Zeki; Arango, Rachel; Clausen, Carol A.; Green, Frederick. 2008. Preliminary investigation of biological resistance, water absorption and swelling of thermally compressed pine wood panels. IRG/WP ; 08-40396. Stockholm, Sweden : IRG Secretariat, 2008: 11 pages