The effect of blue stain on shear strength of cold-set polyurethane resin (PUR) bonds was investigated using lodgepole pine lumber with varying degrees of stain and two different wood grain orientations. While blue stain was associated with definite differences in wood permeability, it had no negative effect on shear strength...
Wood shear walls are the main lateral force-resisting system for wood-frame construction. Water intrusion and subsequent decay around connections can significantly impact shear wall behavior, but these problems are seldom studied. In this study, effects of water intrusion and fungal attack on shear wall capacity were examined using small-scale (610-...
The potential effects of plant derived oils on survival of dampwood termite (Zootermopsis augusticollis) workers was explored on western white pine sapwood blocks. All of the oils rapidly affected protozoa in the hindgut of termite workers and protozoa loss was closely followed by worker mortality. The effects were most rapid...
The potential for preservative migration from treated wood exposed in or above aquatic environments has become a major concern in some parts of the United States. Best management practices (BMP) were designed to decrease the potential environmental footprint of treated wood, but there are few studies assessing the efficacy of...
The potential for using pretreatment with cinnamon leaf oil or juniper foliage oil to improve the durability of viscoelastic thermal compression (VTC)–treated hybrid poplar was explored in a field termite test and a laboratory mold test. The addition of oils prior to VTC processing had variable effects on resistance to...
Routine inspection of wood utility poles to detect internal decay involves drilling holes at or about the ground line. While these holes are useful for detecting internal decay, their presence raises concern among engineers about their potential effects on pole flexural properties. The effect of inspection holes on flexural properties...
Wood I-joists are often left uncovered and exposed to the weather during construction, allowing the oriented strandboard and laminated veneer lumber in these systems to be adversely affected by water absorption. Manufacturers typically specify that these materials be protected from wetting, but this can be difficult in wetter climates. There...
Red oak, Douglas-fir, and ponderosa pine lumber was treated with a silicon/paraffinic system to assess the ability of the treatment to limit dimensional changes and moisture uptake during changes in temperature or relative humidity. The treatment initially had little effect on either property, but the magnitude of weight gain and...
The ability of natural and synthetic hinokitiol, as well as a water soluble derivative (hinokitiol sodium salt), to protect wood against fungal attack was examined. Synthetic and natural hinokitiol provided similar protection. All three materials exhibited similar antifungal activity against Aspergillus niger and Penicillium citrinum on yellow poplar wafers at...
The ability of selected plant extracts from wood and foliage to inhibit mold regrowth on fungal colonized wood was evaluated on Douglas-fir sapwood. Most foliage extracts produced some inhibition of Graphium or Trichoderma species, but isolations of other fungi increased following treatment. Five out of eight wood extracts produced 50%...
Bacillus subtilis and essential oils have been explored separately for their ability to limit colonization by wood stain and mold fungi, but neither approach has been completely effective. One alternative strategy would be to combine the bacterial biocontrol with one or more natural products extracts. In this report, the ability...
Assessing the impact of fungal decay in wood structures poses a major challenge for building inspectors. Although models have been developed to predict degradation rate of building components in varying climatic conditions, most are hampered by the lack of fundamental data on effects of fungal attack on engineering properties. Developing...
The effect of metal end plates on reducing checking of pentachlorophenol-treated Douglas-fir crossarms was evaluated over 13 wet–dry cycles. Check development was variable over the first three to four cycles, and then steadily increased for both plated and nonplated ends of arms; however, both the number of checks and the...
Preservative treatments are required whenever glued laminated beams are exposed outdoors. Treatments can be either water-based systems applied to individual laminations prior to layup or organic solvent–borne systems applied after the beams are fabricated. Water-based systems are not recommended for posttreatment because of concerns over checking and the potential for...
The resistance of three naturally durable heartwood species and a stranded giant bamboo product to fungal and termite (Coptotermes formosanus) attack was evaluated at a test site located near Hilo, Hawaii. Merbau (Intsia bijuga or I. palembanica) and ipe (Tabebuia spp.) were both exceptionally resistant to fungal and termite attack,...
The amounts of treated wood present at a wood recycling center in western Oregon were surveyed over a 10-year period. Treated wood was found at 106 of 112 inspections, but the levels never exceeded 2 percent of the volume present. The amount of treated wood averaged 0.15 percent of the...
The ability to treat Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) with oilborne copper-8-quinolinolate or with waterborne chromated copper arsenate, ammoniacal copper zinc arsenate, or ammoniacal copper quaternary was assessed using commercial treatment facilities in the Pacific Northwest. In general, Scots pine was more easily treated than was...
A solid, crystalline fumigant (dazomet) with and without a supplemental copper compound was evaluated as an internal decay control treatment on Douglas-fir poles in two long-term field tests. Methylisothiocyanate (MITC), the decomposition
product of dazomet, was used as a measure of effectiveness. MITC levels in the wood were above the...
Understanding how silvicultural treatments and changes in the forest resource will affect wood quality characteristics, including heartwood natural durability, is a critical need for forest managers. Because heartwood properties can be affected by environmental disturbances, including silvicultural practices used to grow trees faster, we need to know if increased growth...
While wood plastic composites have gained an increasingly large share of the market for decks and other outdoor structures, there are many questions about the long-term potential for biodeterioration of these materials. While the plastic does appear to retard moisture uptake, thereby slowing the rate of degradation, a number of...
Associations between the golden metallic beetle, Buprestis aurulenta L., and wood-destroying fungi were explored with adult beetles collected from log decks. A variety of fungi were isolated from the beetle bodies by four methods. A total of 863 isolations were made from 59 females and 21 males. There was no...
The effect of supercritical fluid treatment on superficial gas permeability of Douglas-fir was investigated by using carbon dioxide either alone or amended with methanol. Permeability increased in a majority of samples, although nearly one-third of the specimens declined in permeability. Improvements in permeability appeared to be unrelated to variations in...
Adverse effects on mechanical properties from using a supercritical fluid (SCF) to increase preservative penetration of refractory woods were evaluated by treating small ponderosa pine sapwood specimens with supercritical carbon dioxide at 64 combinations of temperatures (35 to 80 C), pressure (1,000 to 4,000 psig), and time (0.5 to 2...
A new laboratory technique to simulate the initiation of wood decay and to assess the effects of incipient decay on material properties is described. Douglas-fir heartwood specimens were exposed to brown-rot (Postia placenta and Gloeophyllum trabeum) fungi for various periods. Bendlng properties were determined by nondestructive and destructive tests, and...
The effect of pretreatment of Douglas-fir flakes with CCA-C, borate, and azaconazole on properties of flakeboard was studied. Flakes had higher retention levels of CCA-C and borate in their ends than in their centers. The distribution of chemicals was uniform in panels, which indicates that the chemicals did not migrate...
The effects of moisture content, flow direction, concentration, and temperature on the diffusion of chloropicrin in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) heartwood were investigated. Diffusion coefficients were strongly affected by wood moisture content. Coefficients for radial and tangential diffusion at the fiber-saturation point were twice as high as those at...
Heartwood from coastal redwood [Sequoia sempervirens (D. Don.) Endl.] is very durable and is often used untreated in harsh environments, such as cooling towers of power or chemical processing plants. Wood in this environment is often attacked by soft rot fungi. Some wood users attempt to bolster protection by including...
Supercritical fluids can markedly enhance preservative treatment of wood, but the high pressures employed can lead to collapse. We investigated the effects of the rates of pressure application and release on displacement of white spruce lumber during supercritical impregnation with carbon dioxide. Displacement was greatest when pressure was rapidly increased...
High concentrations of the fumigant methylisothiocyanate (MITC) will effectively control decay fungi in large wood structures, but the fungitoxicity of low MITC concentrations and the influence of wood moisture content (MC) on its performance are not well understood. The MC of Douglas-fir heartwood greatly influenced the susceptibility of the decay...
Vapam(r) (NaMDC) is the fumigant most commonly used to arrest and control decay of utility poles. While volatile fungitoxins are detectable only 1 to 2 years after treatment, poles treated with Vapam(r) remain free of decay fungi for 6 to 17 years. Vapam(r) decomposes to produce volatile fungicides as well...
Tests were conducted to determine the effect of ACZA composition on fixation and the roles of adsorption and precipitation in fixation. The sites of copper and zinc adsorption within the treated wood and the bonding environment of adsorbed copper were also examined. The results generally support the finding that arsenic...
The development of pressure inside wood during preservative impregnation was studied using Douglas-fir heartwood and ponderosa pine sapwood. Pressure sensors mounted on sample holders provided the most reliable measurements. As expected, pressure equilibrated most rapidly with air as the treatment medium and ponderosa pine as the test species. Pressure changes...
Alder represents an abundant but underutilized resource that has little natural resistance to decay. Treated alder might be used for stakes, posts, or other nonstructural applications. The performance of alder treated with chromated copper arsenate (CCA), copper 8 quinolinolate, zinc naphthenate (ZN), or thiocyanomethylthiobenzothiazole (TCMTB) was assessed in soil block...
The relationship between moisture content and the presence of methylisothiocyanate (MITC) in wood following various applications of sodium n-methyldithiocarbamate (NaMDC) was investigated with small Douglas-fir heartwood blocks. While MITC levels were initially higher in wetter blocks, MITC levels in drier blocks remained more stable over the 8-week test period. The...
The ability of white and brown rot fungi to colonize wood-plastic composites was investigated by measuring weight loss and anatomical changes. Three composite materials were evaluated. The material containing a 70/30 wood-high density polyethylene (HDPE) mixture was most susceptible to fungal attack, while two different 50/50 wood-HDPE composites experienced little...
Studies of the effects of various chemicals on fungal growth are difficult to perform on filamentous fungi because of the difficulty of observing the protoplasm through the rigid hyphal wall, and because most activity occurs in the region near the hyphal tip. However, hyphae can be exposed to certain enzymes...
Differences in stain susceptibility were evaluated on sterile and unsterile samples of freshly sawn, frozen and thawed, or oven-dried and rewetted ponderosa pine sapwood. Samples treated with sterile medium or with medium inoculated with either Pseudomonas putida or Bacillus subtilis were inoculated with selected wood-staining fungi. In general, fresh unsterile...
The effects of supercritical fluid (SCF) impregnation on physical properties of composites were investigated at various pressures, temperatures, and treatment times with carbon dioxide as the fluid and tebuconazole as a biocide. In general, within the ranges tested, SCF treatment had no negative effects on modulus of rupture (MOR), modulus...
A small-scale test was developed to evaluate the ability of fungicides to control decay fungi established in wood. The test, which uses blocks 2.5 x 2.5 x 10 cm, tests the ability of a chemical to migrate from the middle of the block to control a previously established decay fungus,...
This report describes the relationship of incising-induced strength loss in bending as a function of preservative treatment and incising pattern, density, and depth of penetration for various machine stress-rated (MSR) grades of full-size 2 by 4 Douglas-fir, Hem-Fir, and Spruce-Pine-Fir (South) dimension lumber. This study may represent a worst-case "incising...
The high decay resistance of western redcedar (Thuja plicata Donn) is due to the presence of toxic extractives, called tropolones, in the heartwood. Therefore, tropolone content may be used as an indicator of decay resistance. With increment core-sized samples of western redcedar heartwood, we used gas chromatography to measure tropolone...
The air permeability of western hemlock from coastal forests in western Oregon was assessed. Permeability varied widely among trees, as well as by position within individual trees. Permeability tended to decrease with distance inward from the bark, a trend implying that this species produces a heartwood zone. These variations may...
The effect of process variations under supercritical conditions on cyproconazole retention and distribution in ponderosa pine sapwood boards was assessed. While pressure and temperature appeared to affect biocide solubility to some extent, the overall results suggested that biocide movement into wood was influenced more by diffusion than bulk flow. Biocide...
Preservative treatment of whole, wood-based composite products (mainly panels) has disadvantages; problems largely stem from swelling, strength loss, and incomplete or inappropriate penetration during treatment, and distortion during redrying. Pretreatment of comminuted wood prior to mat lay-up is one alternative, though the addition of chemicals may affect bonding during subsequent...
Although boron has many advantages as a wood preservative, this chemical performs poorly in leaching exposures. In this study, we investigated the potential for decreasing the leachability of boron preservatives with polyethylene glycol (PEG). Southern pine (Pinus spp.) test samples impregnated with combinations of sodium borate or boric acid and...
This paper reviews literature on the formation of heartwood and on the components that affect natural durability. It includes discussion about the function of heartwood in living trees, factors influencing the natural durability of heartwood, the process of heartwood formation, and variations in heartwood quantity and quality. Heartwood formation is...
Heartwood durability of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) was studied as a function of vertical and radial position in boles of trees with a wide range of leaf area/sapwood area ratios. Six 34- year-old trees were harvested from each of three plots established 14 years before: very dense,...
This study examines the effects of pressure, temperature, and treatment time on supercritical fluid impregnation of such composites as plywood, particleboard, flakeboard, and medium-density fiberboard. Carbon dioxide with methanol as a cosolvent was used as the supercritical fluid, with tebuconazole as the biocide. Biocide distribution, as measured by extraction and...
Mylone@ and tridipam are two solid chemicals that decompose to produce methylisothiocyanate (MIT), a highly effective wood fumigant. In this study, two techniques -- a rapid, test-tube method and small-scale, wood-block assay -- were used to determine the effect of the pH of various chemical buffers on the decomposition of...
The fungitoxicity of carbon disulfide (CS2), methylisothiocyanate (MITC), or a mixture of these two gases, to selected wood-degrading fungi was studied by using a fumigation apparatus. Both gases are important decomposition products of metham sodium, the most commonly used fumigant for internal treatment of large wood members. Carbon disulfide (up...