Three types of non-toxic polymeric formulations invented using a new approach to wood preservation were challenged with termites and fungi in three-year ground-contact field trials in the sub-tropical climate of Natal. These formulations were copper soaps of carboxylic acid groups of unsaturated fatty acids of waxes and edible vegetable oils; of resin acids of rosin, and, of synthetic unsaturated polyester resins. The formulations self-polymerise within lumena of wood elements after pressure-impregnation and also co-react with carbon-carbon double bonds and aromatic nuclei of lignin. The biocidal mechanism is based on the release of copper by hydrolysis under humid conditions and on the reformation of the same bond on redrying of the treated timber in service. All formulations tested were effective and durable. Rosin formulations at retentions of 0.91 kg/m³ and polyester formulations at retentions as low as 0.4 kg/m³ each out-performed creosote at 37.5 kg/m³.

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