Influence of Thermal Modification and Impregnation with Biocides on Physical Properties of Italian Stone Pine Wood (Pinus pinea L.)

ABSTRACT

Featured ApplicationIn recent decades, the importance of wood has also been increasing for outdoor intended use. A more sustainable approach has turned the attention from faraway tropical forests to local wood, that is, European species. Unfortunately, most of the species are not durable;thus, in order to utilize them in outdoor conditions, protection must be provided. Stone pine (Pinus pinea) is one of the most common tree species in the Mediterranean region, with a great potential in applications with higher added value, instead of being used only for burning or packaging. This investigation explores methods for an improvement of the service life of stone pine sapwood using impregnation and modification techniques.The sudden availability of Italian stone pine (Pinus pinea L.) wood due to the infestation of pathogenic fungi and insects highlighted the need to promote its use as a short supply chain resource in Italy and other Mediterranean countries. However, the durability of stone pine sapwood must be enhanced if outdoor use is to be considered. The impregnability of stone pine wood was studied following the standard EN 351-12008, using immersion, vacuum, and high-pressure methods with natural waxes and organic solvent-based and copper-amino-based preservative solutions. The efficacy of the impregnation was determined by calculating the kilos of preservative absorbed per cubic meter of wood and by measuring the penetration depth of the preservative. Thermal modifications were carried out using five different maximum temperatures, and their efficacy was determined by measuring the mass loss and color change. Subsequent to thermal treatments, the wood was exposed to a water-vapor-saturated atmosphere, and the increase in mass was calculated for different periods. Stone pine and Scots pine sapwoods showed similar response to the treatments with the exception of soaking impregnation methods where stone pine showed higher uptake, in particular when Silvanolin was used. Our investigation shows that stone pine can be a suitable short supply chain resource in Italy that, when impregnated, could be tested for outdoor use, exactly as is the case with Scots pine.