The effect of wood preservatives on the relation between the electric resistance and moisture content in scots pine (Pinus sylvestris L.) sapwood
B W Holleboom, W J Homan
The effect of two types wood preservatives (TBTO and CuHDO) on moisture content measurements with an electric resistance meter in pine sapwood is assessed. High and low concentration impregnated pine sapwood is climatized at different relative humidities. Once climatized the samples are weighed and the moisture content is measured with an electric resistance meter by fixed stainless steel, isolated measuring pins. Subsequently the wood is dried for 48 hours at 103°C and weighed to gain the correct climatized moisture content. The reading values of electrical moisture content measurements are compared to the actual moisture content. Compared to the original correction lines for pine, an increase in concentration of metal ions leads to a steeper slope, i.e. the conductivity of the treated wood increases. The change in conductivity is so small that electrical resistance measurements are still practicable. However, for precise measurements new correction lines, which depend on concentration and type of preservative, need to be established.