Abstract: Comparison on decay- and leach-resistances among 3 quaternary ammonium salts,namely:didecyl dimethyl ammonium chloride,didecyl dimethyl ammonium acetate and didecyl dimethyl ammonium propionate,as wood preservatives were conducted by applying them to Populus ussuriensis,wood specimen,using Coriolus versicolor(L.ex Fr.)Quel as test fungus.At the retention of 3.8, 3.8, 3.9 kg/m³,testing results showed the mass loss to be 7.2%, 7.9%, 7.6%,respectively.Didecyl dimethyl ammonium acetate in wood showed stability against neutral and alkaline solutions,whereas the propionate showed stability against acidic solution.

Key words: quaternary ammonium compound, wood preservative, leach resistance