Near-infrared spectroscopy as a potential quality assurance tool for the wood preservation industry

Abstract

Preservatives are used to extend the service life of wood used in situations where it is vulnerable to biodegradation. Wood preservation standards typically specify quality assurance procedures to differentiate heartwood and sapwood and to measure preservative loading and penetration. For spruce and hem–fir there are no reliable chemical spot tests to differentiate sapwood and heartwood. This makes it more difficult for these species to meet penetration requirements. For many of the recently introduced carbon-based preservatives, the only methods available to determine penetration involve detecting a surrogate in the formulation, or only some of the active ingredients. Multivariate models based on near-infrared spectroscopy (NIRS) have been used to predict a wide range of wood properties over the past 20 years. The present research evaluates the potential use of NIRS-based models as quality assurance tools for the wood preservation industry. Models were developed to differentiate hemlock and amabilis fir sapwood and heartwood. NIRS-based models were also able to differentiate untreated wood from wood treated with DDACarbonate and wood treated with tebuconazole. Models developed to predict DDACarbonate and tebuconazole retention were moderately accurate, but likely not precise enough to replace current quantitative assays.