Results of a ten-year marine exposure trial at Townsville and Port Stephens are presented. Sawn Pinus radiata and natural round Eucalyptus obliqua specimens were treated with preservatives including creosote (HTC), pigment emulsified creosote (PEC), chlorothalonil, and the oil emulsions of CCA called PROCCA and HYCON. Basic zinc chloride treatment was also exposed at Townsville. Some of the findings were that P9 oil treatment of Pinus radiata prevented teredinid attack over ten years, although specimens had failed to Limnoria. A double treatment of CCA plus oil may therefore be effective. PEC performed sightly better than HTC on an equivalent creosote retention basis. Treatment using 5% chlorothalonil in oil generally gave similar performance to HTC. PROCCA performed better than CCA at equivalent CCA retentions against teredinids, most likely due to the small amount of oil (5%) present in the formulation. Basic zinc chloride provided resistance to marine borers, although treated P. radiata was softened due to the acidity of the treatment solution. One of the better performing timbers was PEC treated turpentine (Syncarpia glomulifera), which was unexpected as retentions achieved were below standard requirements for hardwoods. In the tidal zone, Sphaeroma caused more damage to CCA treated P. radiata at Townsville than Port Stephens, while Limnoria tripunctata was more active at Port Stephens than Townsville.

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