Termite Field Tests of Various Timber Species Treated with permethrin using supercritical carbon dioxide
A Qader, L J Cookson, J W Creffield, D Scown
Termite field tests were conducted on permethrin-treated Eucalyptus obliqua heartwood, Pinus radiata sapwood and P. radiata LVL. The permethrin was impregnated using either supercritical carbon dioxide (scCO2) or light organic solvent preservative (LOSP) systems. Comparative permethrin retentions were most accurately achieved in P. radiata sapwood, where no difference between impregnation systems was found in performance against Coptotermes acinaciformis, and a minor difference in favour of scCO2 was found against Mastotermes darwiniensis. P. radiata LVL specimens treated using scCO2 performed slightly better than those impregnated with LOSP, reflecting slightly higher permethrin uptakes in the former. E. obliqua heartwood was completely destroyed by M. darwiniensis when impregnated with LOSP but was mostly sound when scCO2 was used, suggesting improved uniformity of penetration by the latter treatment.