Primer cure and adhesion after light organic solvent preservative treatment of Radiata pine

Abstract

This study examined the effect of preservative treatment and wood drying history on paint primer cure and adhesion for New Zealand radiata pine (Pinus radiata D. Don). Double Vacuum LOSP treatments resulted in a significantly lower LOSP uptake than did Lowry treatments, for both sapwood and heartwood. Wood drying history had no effect on uptake by sapwood, but did affect uptake by heartwood; high-temperature-kiln-dried heartwood retained more solvent than air-dried or conventionally dried heartwood. For sapwood, LOSP treatment method and wood drying history did not significantly affect either primer cure or primer adhesion. For heartwood, primer adhesion in the early stage of cure was better with Double Vacuum treatments. Double Vacuum treatments also resulted in a higher cure of primer, two days after priming, than did Lowry treatment when either conventionally or high-temperature-kiln-dried heartwood was used, but no significant difference was found with air-dried heartwood. It was concluded that, for radiata pine heartwood, Double Vacuum treatment, combined with either air-drying or conventional drying, will reduce LOSP uptake and give better primer performance, so long as effective ventilated solvent removal is achieved before priming.