Laser incision offers great potential for increasing the permeability of wood to preservative or other fluids. Wood modification systems have a greater requirement for full impregnation than traditional preservative systems, and envelope treatments are not sufficient. The bulking effect of many wood modification systems means that uniformity of penetration by reagents is essential. Therefore laser incision offers potential to increase permeability of timber for wood modification. Experiments were conducted on four species of wood, to investigate the altered flow. These species were southern yellow pine, European beech, Sitka spruce and European redwood.
Blocks were sealed on all faces, limiting fluid uptake to a single laser incision. Laser incisions were made using UV laser, and the depth of focus and number of shots was varied. Pressure treatment was undertaken using an aqueous dye system, and quantities of fluid taken up were recorded gravimetrically, as well as by observation of the dye within dissected wood blocks. This allowed observation and measurement of longitudinal and transverse flow within different planes in the sample.
The significance of the resin canal network was demonstrated in some species (southern yellow pine) while pit aspiration dominated the reduced flow observed for spruce. Hardwood flow is dominated by the vessel network. As a result of these flow observations different incision strategies will be developed to maximise fluid uptake and distribution uniformity in species selected for further study.