Rod Stirling

Western red cedar extractives associated with durability in ground contact

Western red cedar (WRC) is well known for its natural durability. However, the roles of all the extractives that may be associated with this durability are not fully understood. The literature primarily credits the thujaplicins, with a lesser role for the lignans; however, previous work has identified highly durable material with low thujaplicin content. To elucidate the relative importance of various extractives, the decay resistance of WRC stakes at four test sites was compared with data on the content of specific extractives to determine whether there was any detectable association. The concentration of plicatic acid, a lignan, was associated with the decay resistance of WRC lumber in ground contact. An unidentified, unquantified compound (B) appeared to be similarly associated with decay resistance. The thujaplicins were only weakly associated with the decay resistance of WRC in ground contact.

Residual Extractives in Western Red Cedar Shakes and Shingles after Long-Term Field Testing

Western red cedar shakes and shingles were analyzed for extractives after 25 and 33 years of exposure in a field test to better understand the extractives associated with long-term durability. Only minimal concentrations of thujaplicins were found, but plicatic acid was still present in significant quantities. Plicatic acid or other uncharacterized compounds that remain in the wood may play a more important role in the durability of shakes and shingles than previously thought.

Potential contributions of lignans to decay resistance in western red cedar

Abstract Recent work examining the correlations between heartwood extractives in western red cedar and decay resistance in ground-contact field tests identified two compounds that were moderately correlated with decay resistance—plicatic acid and an unknown compound. The aim of the present work was to identify the latter compound and to further probe the correlation between both of these lignans and decay resistance. Chromatographic and mass spectral data indicated that the latter compound was plicatin—the lactone of plicatic acid. Extractives fractions containing plicatic acid, plicatin, and polymeric lignans, believed to be derived from these compounds, were impregnated into ponderosa pine sapwood blocks and evaluated for their ability to resist decay by two brown-rot fungi. Impregnation of plicatic acid, plicatin, their combination, or polymeric western red cedar extractives in pine sapwood did not inhibit decay by the fungi evaluated. However, both plicatic acid and plicatin had high radical scavenging activity, and moderate ferrous iron chelating activity. It is proposed that these compounds contribute to decay resistance not as fungicides, but rather via alternative pathways. These could include interference with redox cycles associated with decay, and restricting moisture by reducing cell wall void volume.

Improved Coating Performance on Wood Treated with Carbon-Based Preservatives and an Ultraviolet/Visible Light Protective Precoat

Abstract Transparent and semitransparent coatings applied to wood products often fail due to photochemical degradation and colonization by black stain fungi. Longer-lasting coatings are needed to e...

Kraft pulping of wood treated with carbon-based preservatives.

No abstract available

Prediction of the Decay and Termite Resistance of Western Red Cedar Heartwood

Abstract Western red cedar (WRC; Thuja plicata) is highly valued for its natural durability. Rapid methods to assess heartwood durability are needed to identify breeding stock that will ultimately ...

Control of Black Stain Fungi with Biocides in Semitransparent Wood Coatings

One of the frequent signs of early failure in semitransparent wood coatings is colonization by “black stain” fungi, such as Aureobasidium pullulans. A laboratory method evaluating the ability of va...

Sensors in the Forest Products Industry

The forest products industry takes a natural resource with variable properties and transforms it into a wide range of engineered products with increasingly demanding material specifications. To meet the demands of the market, and maximize the value of the resource, companies must measure wood product properties and optimize production processes. There are many steps along the value chain where information is needed to aid in processing and end use decisions. This information is increasingly being obtained from automated sensing systems that can provide real-time information in the forest, during manufacture, or in service, and enable rapid decision making to improve process or product performance. Sensors must provide reliable data upon which processing or end use decisions can be made. Sensors and data processing techniques continue to evolve to meet this challenge. The papers in this special issue highlight some of the advances in sensing technology applied to forest products and build on recent research in special issues of the Canadian Journal of Forest Research (Trung and Leblon 2011) and the Forestry Chronicle (Leblon and Tsuchikawa 2013). Several papers in the current issue use nearinfrared spectroscopy (NIRS) to predict wood properties, including moisture content and basic specific gravity in logs (Hans et al. 2015a) and surface quality of aspen veneers (Koumbi-Mounanga et al. 2015). NIRS-based hyperspectral images are used to estimate moisture content and density distributions in subalpine fir board (Haddadi et al. 2015a, b). Timeof-flight NIRS is used to measure variations in air-dry wood density (Hans et al. 2015b). Finally, a novel densitometer based on a near-infrared laser system is introduced (Kitamura and Tsuchikawa 2015). Other sensing technologies described include a novel microwave tomographic system for wood characterization (Pastorino et al. 2015). The use of magnetic resonance imaging (MRI) to measure water in wood (Lamason et al. 2015) and woodplastic composites (Gnatowski et al. 2015) is described. A Ground Penetrating Radar (GPR) method to measure log moisture content is described (Hans et al. 2015c). An electronic nose, based on a tin oxide semi-conductor thin film that can detect wood combustion products is introduced (Joseph et al. 2015). Finally, grain angle measurement and mechanical modeling are demonstrated to improve strength grading of timber (Viguier et al. 2015). We encourage researchers to continue to build upon the technologies presented in this special issue and to develop the next generation of sensing technologies to maximize the value of global forest resources.

The Effect of Fungal Preinfection on the Efficacy of Mold and Sapstain Control Products

ABSTRACT Efficient use of sapstain control products requires information on the effectiveness of the actives and formulations against different types of fungal challenges. The present work examines...

Ten-Year Performance of Stakes and Decking Treated with Copper Azole Type B and Alkaline Copper Quat Type D (Carbonate)

Abstract Development of wood preservatives typically involves laboratory tests using mycelial inoculation and field tests with through-treated small-dimension pine sapwood samples. These preservati...