Specialty Timbers New ZealandSearch technical reports
Drying and pressure treatment of poplar round produce
By D. H. Williams and I. G. Simpson, July 1986.
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Executive summary
Posts of an Italian-hybrid poplar were kiln dried at high (120ºC/70ºC) or medium (70ºC/60ºC) temperatures or air dried before pressure treatment with multi-salt preservative. Drying was slow in all cases and hitemp dried posts had internal checking, strongly correlated with diameter, at levels up to very severe. No internal checking was found in medium temperature dried posts. The external appearance of both series was excellent. Solution uptake was high in both kiln dried series with little variation. Highest uptake was in the hitemp dried series. It was concluded that medium temperature kiln dried poplar posts could meet TPA requirements and might be acceptable to the commercial end-user but would be uneconomically slow to dry, have poor nail or staple holding properties, and low strength. Air dried posts were generally treated at a moisture content above that specified by TPA. Uptake was unsatisfactory but distribution acceptable, with sapwood completely penetrated. Surface checking was at normal levels.
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