Evaluating the Effects of Post Dip-Treatment Laser Marking on Resistance to Feeding by Subterranean Termites

IRG/WP 16-10854

R A Arango, B Woodward, S Lebow

Dip-treatment of wood packing materials is often used instead of pressure treatment mainly because of issues relating to simplicity and cost. Packaging boxes fabricated for the United States Army are required to be dip-treated for at least one minute in an approved preservative solution prior to use. These boxes are expected to have a service life of up to 20 years in a wide variety of environments. Recently, there is interest in using laser markings on these boxes, which can result in a breach of the preservative shell, potentially increasing susceptibility of the wood to termites and decay. Alternatively, thermal modification of the wood by the laser may be sufficient to protect these marked areas. In this study, solid southern pine wood and two types of plywood samples were dip-treated with copper or azole based preservative formulations. Leached and unleached blocks were then evaluated using modified AWPA testing methods to determine if laser marking increased susceptibility to feeding by subterranean termites. Termites preferentially fed within the laser marked areas as compared to non-lasered areas of the block. This suggests that laser marking is a breach of preservative treatment and has the potential to strongly affect the long-term durability of these containment boxes where there is termite pressure. However, when unleached-lasered samples were compared to leached-non-lasered samples, termites showed a stronger preference for feeding on the non-lasered surfaces of leached blocks and the laser marked areas of unleached blocks, indicating that leaching, rather than laser marking, may have more of an effect on termite feeding preference. Results from this study will be used in development of new methods addressing long-term labelling protocols for dip-treated wood packing materials.

Keywords: biodegradation, wood-packing materials, leaching, thermal modification

Conference: 16-05-15/19 Lisbon, Portugal

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