Abstract
A series of metallic naphthenates were tested for their fungicidal and termiticidal effectiveness in the laboratory. Copper naphthenate peformed better than zinc naphthenate in wood decay control.
In vacuum/soak impregnation treatment [JIS A 9301 (1976)], copper and zinc naphthenates could satisfactorily depress decay fungi at retentions of 0.5 and 1.0 kg/m3 as an elemental metal, respectively [JIS A 9302 (1976) ]. The former chemical proved effective in protecting timber from decay at 2.1kg/m3 even after the recently amended severer leaching schedules [JIS A 9201 (1991)]. When applied to brush treatment, copper naphthenate was effective at 2% Cu and 3%Cu concentrations, respectively after weathering of JWPA Standard 1 (1979) and the severer weathering [amended JWPA Standard 1 (1989) ], while zinc naphthenate did not perform well even at 4%Zn after the new weathering scheme. Noticeable effects of acid values were not shown for copper naphthenates, but for zinc naphthenates in brush application.
As for the termiticidal effects of the test chemicals, copper naphthenate was efficacious at 1% Cu in wood block test [JWPA Standard 11 (1) (1981)] in which pine sapwood blocks treated with the chemicals by brushing were exposed to Formosan subterranean termites for three weeks. Zinc compounds were less effective, and 2%Zn was required to control termite attacks.
