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Comparative response of Reticulitermes flavipes and Coptotermes formosanus to borate soil treatments
1991 - IRG/WP 1486
Eastern (Reticulitermes flavipes [Kollarl]) and Formosan (Coptotermes formosanus Shiraki) subterranean termite workers (Isoptera: Rhinotermitidae) were exposed to borate-treated sand in an indirect exposure tunneling assay in the laboratory. In the ten day assay period, both termite species readily penetrated sand containing 5000, 10000, or 15000 ppm (wt. of compound / wt. of sand) disodium octaborate tetrahydrate (Tim-BorÒ) or zinc borate (Firebrake ZB-FineÒ). With Reticulitermes flavipes, significant mortality (85-93%) resulted from workers tunneling through sand treated with 5000 ppm disodium octaborate tetrahydrate (higher concentrations were also effective), or 15000 ppm zinc borate. Responses of Coptotermes formosanus workers were lesser and more variable, with only concentrations of 10000 and 15000 ppm zinc borate resulting in mortality 70-89%) significantly different from that in the control groups. These results suggest that differences between these two species in tunneling behavior may reduce exposure of Coptotermes formosanus to the borate-treated sand.
J K Grace


Borate thermal treatments
1992 - IRG/WP 92-3715
Green, partially seasoned (air-dried, steam conditioned), or kiln-dried southern pine timbers were treated thermally using 15% disodiumoctaborate tetrahydrate solution. After treatment, sections were stored under non-drying conditions to allow for diffusion. Results showed that effective treatment meeting the AWPA minimum retention (0.17 B203 pcf [2.72 kg/m³] in the outer inch) and penetration (2.5-in [64-mm] or 85% of the sapwood) could be obtained only with certain combinations of seasoning, treatment, and diffusion storage. The best results in terms of both retention and penetration were obtained with material steamed and stored prior to treatment using a 10-min hot bath time. Kiln-dried timbers could not be treated effectively. The results suggest that non-conforming treatment of green or partially seasoned timbers will require higher solution concentrations, higher hot bath temperatures, and/or longer diffusion periods to meet required standards. Results also indicated that treatment of smaller stock in dimension sizes (up to 2-in [50-mm]) should be feasible.
H M Barnes, R W Landers, L H Williams


Effect of protective additives on leachability and efficacy of borate treated wood
2002 - IRG/WP 02-30290
Borate preservatives have been used extensively in many countries as an effective means for protecting wood against fungal and insect attack especially in interior environments. Under exterior conditions, borate compounds have a main disadvantage as they can be leached from treated wood as a result of their water solubility. In this study, we compared the potential of different additives for reducing the leachability of boron preservatives from treated wood. Scots pine sapwood (Pinus sylvestris) and poplar (Populus trichocarpa x deltoides) test samples were vacuum treated with 1 % BAE (Boric Acid Equivalent) disodium octaborate tetrahydrate (DOT) solutions containing various additives e.g. glycerol/glyoxal, polyvinylpyrrolidone (PVPY), a commercial resin compound and a commercial water repellent. The European Standard EN 84 was used as a leaching test for both coated and uncoated specimens. The results of chemical analysis of leachates taken at different periods showed that the use of protective additives reduces the boron leachability. The glycerol/glyoxal additive applied to treated pine sapwood showed the best performance. The percent of boron retained in uncoated pine sapwood was 26% while coated samples still retained 45% after 14 days of intense leaching. Similar tests on poplar revealed 19% and 34% for uncoated and coated samples, respectively.This represents a gain of 20 to 25% compared to pure DOT treated specimens of both wood species. Preliminary biological tests were carried out on malt agar using a miniblock technique for uncoated pine sapwood and beech, with Poria placenta and Coriolus versicolor, respectively. After six weeks of exposure to fungal attack all boron protective systems tested proved their effectiveness, as none of the test samples exhibited a mass loss exceeding 4%. The reference 1% BAE without protective additives showed an average mass loss of 15%. Finally, test data are reported of standard EN 113 testing in view of a further evaluation of the biological efficacy of combined DOT-additive treatments.
A Mohareb, J Van Acker, M Stevens


Protection of OSB against termites by incorporation of different actives via glue line treatment
2008 - IRG/WP 08-30453
Different organic actives and zinc borate were incorporated into OSB during the manufacturing process to enhance the resistance against termites. Tests according to EN 117 revealed excellent performance of thiacloprid. Other organic actives such as permethrin might be effective when used in higher amounts. Zinc borate failed the test by far.
S Donath, P Spetmann, T Jaetsch, T Zahlmann


Tests on the effectiveness of concentrated borate wood preservative
2009 - IRG/WP 09-30500
Tests were carried out to examine the toxicity of concentrated borate wood preservative to termites, fungi and mammals. The results showed that the preservative treated timber had high resistance to termite or decay and its acute oral toxicity belonged to low grade. The research shows that concentrated borate solution is an environmentally sound preservative and can be used in non-pressure treating.
Su Haitao, Zhang Yanjun, Xie Guijun, Chen Lifang, He Xuexiang


The Chemical and Biological Properties of Polymeric Betaine
2009 - IRG/WP 09-30512
Didecyl polyoxyethyl ammonium borate (DPAB), also known as Polymeric Betaine, was developed as a co-biocide for chromium-free copper based wood preservatives in Europe in the 1980’s. DPAB as a wood preservative has been reported previously. This paper summarizes the chemical, physical, and biological properties of DPAB.
H Härtner, S Schmitt, Futong Cui, H M Barnes


Options for accelerated boron treatment: A practical review of alternatives
1985 - IRG/WP 3329
Boron wood preservatives are almost exclusively applied by momentary immersion and block diffusion storage. Alternative techniques are described which can be used to accelerate boron treatment. Diffusion coefficients have been derived to define the acceleration of diffusion with increasing temperature. Schedules are described for pressure impregnation of green timber, involving steam conditioning, evacuation and alternating pressure method treatment. Timber Preservation Authority penetration and retention requirements can be met in approximately 4-5 h. The optimum schedule, however, included a 12 hour holding period between steaming and preservative treatment. A method of applying boron preservatives as a vapour is described, Trimethyl borate vapour reacts with wood moisture to form boric acid. The kinetics of this reaction, however, are very fast. This limits treatment to timber dried to very low wood moisture contents.
P Vinden, T Fenton, K Nasheri


Movement of boron from fused boron rods implanted in Southern pine, Douglas fir, red oak, and white oak timbers
1995 - IRG/WP 95-30061
This paper reports the distribution of boron from fused boron rods installed into six-inch (15.2 cm) square timbers of Douglas-fir, Southern Pine, red oak and white oak exposed aboveground. The composition and size of rods was: sodium borate and sodium borate-copper oxide (8.5 x 100 mm²); sodium borate-copper, sodium borate and boric oxide-copper oxide (12 x 76 mm²). The boric acid equivalent was roughly monitored by the curcumin/salicylic acid color test and the presence of copper was detected by the chrome azurol-S reagent. One year after installation of rods, movement of boron was determined by application of curcumin dye to increment cores removed at various distances from the site of boron rod installation. A portion of a sodium borate treated Southern Pine timber was also analyzed by spraying curcumin dye on sawed longitudinal and transverse sections. At 2 years, one foot sections were removed from all timber species, sawed as above, and boron and copper detection reagent sprayed on the sawed surfaces. Movement of copper from rods in all timbers was virtually nil. Both transverse and longitudinal movement of boron from rods was greatest in Southern pine which also had the highest moisture content. Movement of boron was next best in red oak. There was little movement of boron away from the rods in white oak and Douglas-fir.
T L Highley, L Ferge


Sequential exposure of borate treated Douglas-fir to multiple Formosan subterranean termite colonies in a 40-week field test
1993 - IRG/WP 93-10006
Douglas-fir boards (ca. 74.5 g) pressure-treated with disodium octaborate tetrahydrate (DOT) retentions of 0 (controls), 0.88, 1.23, 1.60, or 2.10% (weight/weight) DOT were sequentially exposed to four active field colonies of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), in an above-ground field test. Samples were placed in contact with each colony for 10 weeks, with oven-dry weight losses determined between exposures, for a total termi exposure period of 40 weeks. Feeding activity differed among termite colonies, with the control wood samples having mean weight losses of 1.3-15.1% of their initial weight during each individual 10-week termite exposure. The two lower borate retentions (0.88 and 1.23% DOT) were virtually equal efficacy, with mean wood weight losses during each individual 10-week exposure ranging from 1.2-4.6%. Feeding was negligible at the two higher borate retentions, with mean wood weight losses from termite feeding during each 10-week period ranging from 0.7-1.3% with 1.60% DOT, and 0.3-0.9% with 2.10% DOT. Total cumulative wood weight losses over the 40 week exposure were: 10.2% (0.88% DOT), 8.7% (1.23% DOT), 3.6% (1.60% DOT), and 2.4% (2.10% DOT).
J K Grace, R T Yamamoto


Diffusion of fused borate rods in top ends of poles
1989 - IRG/WP 3518
Diffusion tests of fused borate rods were carried out on extremities of sapwood poles in service. Rods were set in drills under the cone with or without addition of liquid Boracol 40. After one year of weathering, a good diffusion in the slice under the cone and even below the slice and in the cone itself was observed in Scots pine and spruce poles. The rods were still intacts and constitute, in fact, a reserve of boric acid for the future. This type of treatment would be satisfactory as secondary treatments of poles in service.
D Dirol, J P Guder


Performance if internal remedial treatments to arrest fungal attack in poles and large timbers
2018 - IRG/WP 18-40834
Internal remedial treatments have been used to arrest internal fungal attack in utility poles and other large timbers. Water diffusible systems and volatile fumigants have both been used for this purpose. While both work, it is important to understand the performance attributes of each system. This paper reviews the literature on both systems and makes recommendations for future research.
J J Morrell


The Role of Coformulants in Preventing Bacterial Biotransformation of IPBC
2002 - IRG/WP 02-10436
The inhibitory effects of disodium tetraborate decahydrate and benzalkonium chloride (BAC), two common coformulants of IPBC in antisapstain treatments, on an IPBC-transforming enterobacterial isolate ‘W1’ were determined by their effect on the specific growth rate constant in vitro. The IC50s of IPBC, BAC and borate were found to be 0.46, 0.026 and 5.7 mM respectively. The IC50 of the Arch antistain product AntibluTM Select was 0.024 mM, based on its BAC content. Although their IC50’s were significantly different, it was clear that the vast majority of the bacterial toxicity of the AntibluTM Select was due to its BAC content. The degradation of 0.4 mM IPBC by the bacterium W1, as measured by the accumulation of its degradation product, iodide, in liquid culture, was completely inhibited by BAC concentrations greater than 18 μM, and the toxicity of the spent culture medium to Aspergillus niger, as measured by an antibiotic assay disc assay, was not ameliorated above this concentration. Below 18 μM, the toxicity of the spent broth was significantly reduced, and the accumulation of iodide occurred rapidly. Demonstrating the toxicity of BAC to bacteria, and its consequent inhibition of IPBC degradation in vitro, are indicative of the importance of coformulation in controlling bacteria that might otherwise cause preservative loss, and of their significance in determining the ultimate environmental fate of cobiocides.
S R Cook, D J Dickinson


Emission of trimethyl borate and methanol from radiata pine (Pinus radiata D. Don)
1995 - IRG/WP 95-30088
Sawn and kiln dried radiata pine conditioned to 3, 6, and 12% moisture content was treated with trimethyl borate (TMB). The treated wood samples were placed in mini-desiccators maintained at 20 or 40°C. The air space within the mini-desiccator was analysed for TMB and methanol. An initial period of emission of TMB and methanol was observed. This was followed by a period of gradual dissipation of both TMB and alcohol. There was an equilibrium of 2 ppm and 60 ppm respectively of TMB and methanol for 12% moisture content timber stored at 20°C. Dissipation was slower for 6% and 3% moisture content timber. Higher temperatures resulted in higher concentrations of TMB and methanol during the emission and dissipation stage.
F J Romero, P Vinden, J A Drysdale


Effect of borate on uptake and efficacy of an anti-sapstain treatment
2005 - IRG/WP 05-30380
The potential for using borates to enhance uptake and efficacy of propiconazole-based anti-sapstain chemicals was assessed on ponderosa pine sapwood wafers. Borates had no consistent effect on either net solution absorption or propiconazole distribution in the wood. Even small amounts of borate, however, markedly improved the performance of propiconazole against fungal discoloration. These results are consistent with previous tests of borate addition to other fungicides and highlight the potential for using less expensive ingredients to boost the performance of more costly biocides.
Jianju Luo, Hua Chen, J J Morrell


Preliminary evaluation of borate baits and dusts for eastern subterranean termite control
1990 - IRG/WP 1433
Borates are of potential use in the development of baiting systems for subterranean termite control. In the 15-day laboratory assays reported here, the oral toxicity of disodium octaborate tetrahydrate to Reticulitermes flavipes (Kollar) was evaluated under choice and no-choice conditions. These assays suggest a range of 2500 to 5000 ppm to be applicable in developing baits, and that concentrations greater than 5000 ppm may deter feeding. Laboratory assays with borate dusts (disodium octaborate tetrahydrate, zinc borate, and a fine-grain zinc borate) are also reported. In a toxic variation of mark-release methodology, these materials are passed among the test group by grooming foragers exposed to the dust. In these assays, 10% of the test group was exposed to the borate dust, then released placed in contact with unexposed workers in a simulation of a field release. Zinc borate treatment elicited the greatest mortality (99-100%), although disodium octaborate tetrahydrate also elicited mortality significantly greater than that in the control groups. These results suggest that less soluble borates may be more efficient dust toxicants, and that capture and dust-treatment of a portion of the foraging termite population could elicit high mortality among termites contacting the treated individuals after their release back into the colony.
J K Grace, A Abdallay, J M Sisson


Leachability of borate-modified oriented strandboard: A comparison of zinc and calcium borate
2002 - IRG/WP 02-40232
The leachability of boron in zinc and calcium borate-modified oriented strandboard (OSB) was investigated in this study. The leaching experiments were conducted by exposing edge-sealed OSB samples under running water for 8, 24, 72, and 216 hours. The results were compared with those from the unleached controls. Boron leaching of the modified OSB occurred upon the initial water exposure, and the leaching rate decreased as the leaching time increased. Borate type, initial BAE level, wood species, and sample thickness swelling significantly influenced the leachability. There was no consistent effect of polyethylene glycol (PEG) on zinc borate leaching. Calcium borate with a smaller particle size helped reduce its leachability. The glueline washing due to thickness swelling of the test samples under water and decomposition of the borate to form less water-soluble boric acid are thought to be two possible causes for the observed leaching. The relationship between assayed BAE and leaching time followed a decaying exponential function for zinc borate OSB and a Harris decaying power function for calcium borate OSB. The material constants of the regression models allow comparing leachability of the modified OSB for various wood species. A unified leaching method for treated wood composite materials is needed.
S Lee, Q Wu


Ten year field test with a copper-borate ground line treatment for poles
1993 - IRG/WP 93-30017
A wood preservative paste consisting of borax and copper naphthenate has been tested to determine its efficiency in protecting wood from decay fungi and insects. The paste was applied to polyethylene-backed wraps that were fastened to the below-ground portions of unseasoned southern pine pole stubs. After 4 years of exposure in Mississippi, the untreated control stubs were completely deteriorated. The below-grade portions of the treated stubs remained sound after nearly 6 years of exposure due to movement of copper and diffusion of the borate throughout the cross section. Borate and copper also moved vertically in the stubs and was present in sufficient amounts to protect sections of the stubs as high as 3 feet above grade. After 9 years of exposure, the below-grade portions of the treated stubs had limited areas of decay and no termite damage; the majority of the cross section remained sound. Wood analysis indicated that concentrations of borate in the sound areas were about 1/10 the estimated toxic threshold. A visual examination and push test indicated that the treated stubs continued to be protected at groundline after 10 years of exposure. It is hypothesized that the continued protection of the below-grade portions of the stubs against both decay fungi and subterranean termites is the result of copper-borate complexes that have formed in the wood.
T L Amburgey, M H Freeman


A Preliminary Report on the Properties of Engineered Wood Composite Panels Treated with Copper Naphthenate
2005 - IRG/WP 05-40294
This paper reports on our preliminary investigation of the properties of randomly oriented strandboard which had waterborne or powdered copper naphthenate (CuN) incorporated into the board during manufacture. When compared to zinc borate-treated controls (ZnB), the mechanical properties of strandboard (MOR, MOE, work-to-maximum load, internal bond strength) were not adversely affected by treatment with either form of copper naphthenate. In general, values for mechanical properties followed the trend untreated controls > waterborne CuN = powdered CuN > ZnB. Water absorption and dimensional properties followed a similar trend. This preliminary study suggests that CuN is a viable alternative treatment for engineered wood composites.
J W Kirkpatrick, H M Barnes


Albumin borate: A new non-toxic, wide-spectrum, long-term wood preservative
1998 - IRG/WP 98-30167
Boron, widely recognized for its broad range of activity towards both fungi and insects and for its low mammalian toxicity, can not provide long term protection to treated timber due to its high leachability. Boron, in the form of boric acid, can be partially fixed to timber by the formation of an association with egg albumin, which is insolubilized by heat-induced coagulation. Chemical investigations on fixation mechanisms of boric acid by egg albumin indicated that both acid-base salt formation occurs, as well as the formation of boric acid-albumin complexes, depending on the boric acid/protein ratio. In treated timber, a chance in protein conformation in presence of boric acid, has been shown by scanning electron microscopy. These mechanisms, partly reversible, while greatly retarding its leaching, leave small amounts of boron free to exercice its activity when needed. Boron leaching as a function of time, appears to tend to an equilibrium value, which one differs in the case of an albumin coagulum alone from what is obtained by leaching treated wood samples. Accelerated biolocical tests using such treated timber have shown that albumin borate used as wood preservative has effectiveness against wood decay, and have durability performances comparable to those obtained with CCA.
M-F Thévenon, A Pizzi, J-P Haluk


Treatment of wood-based panel products with volatile borate
1990 - IRG/WP 3616
The paper presents recent developments in the use of volatile borate esters for the preservative treatment of wood based board materials. Several advances on previous reports are discussed. In laboratory studies, treatment times of approximately ten minutes at 20°C on boards at equilibrium moisture content provided full penetration and retentions of 1% wt/wt boric acid. Biological tests have been conducted on a wide variety of boards treated by the vapour boron method. In all cases a retention of 0.7% wt/wt boric acid gave complete protection from decay. These results are considered with regard to parallel studies on solid wood by colleagues at the Forest Research Institute, Rotorua. The advantages of vapour boron treatment for wood based board materials are discussed.
P Turner, R J Murphy, D J Dickinson


Preservative treatments of window components with a water-based borate formulation
2000 - IRG/WP 00-40171
Factory finished window joinery components were treated with an aqueous borate preservative in order to investigate penetration and retention levels, associated drying times; and the potential impact of using a water-based treatment on finished items. It was found that by using borates applied by light double vacuum schedules, it was possible to meet standards for penetration and retention, to air dry components within 48 hours; and to avoid other potentially significant negative impact usually associated with aqueous treatments. It is also suggested that current penetration requirements are inappropriate for mobile preservatives. This initial study indicates that it is possible to replace organic solvent carried preservatives with water-borne technology. The potential impact within Europe is of significance as most authorities have introduced mandatory requirements to move from solvent to aqueous systems where it is shown possible to do so. These treatments have now been adopted commercially by some treaters in the UK and are being considered by window manufacturers in Germany and Sweden.
J Jermer, J D Lloyd


Wood protection by surface treatment of two borate preservatives, TIM-BOR® and BORA-CARE®, for the formosan subterranean termite and eastern subterrean termite
1993 - IRG/WP 93-10044
TIM-BOR® (disodium octaborate tetrahydrate: DOT, Na2B8O134H2O) and BORA-CARE® (40% DOT in ethylene glycol) are two borate products marketed for treating wood in use by brushing or spraying onto the wood surface. The active ingredients presumably diffuse into wood by the 10-15% existing wood moisture. Few data, however, are available to demonstrate the diffusion rate. Su & Scheffrahn (1991) suggested that diffusion rate of BORA-CAREä is quite slow but may be enhanced by the moisture brought in by termites into wood. As there is an increasing interest in using these products for remedial control of subterranean termites, there is a need to understand how do they behave. The object of this study is to examined the termiticidal effects of borate surface-treated wood against the Formosan subterranean termite, Coptotermes formosanus Shiraki, and the eastern subterranean termite, Reticulitermes flavipes (Koller).
M Toroko, N-Y Su


Laboratory evaluation of borate formulations as wood preservatves to control the subterranean termite coptotermes acinaciformis (isoptera: Rhinotermitidae) in Australia
2001 - IRG/WP 01-30266
The termiticidal efficacy of Borocol (sodium octaborate tetrahydrate), boric acid, bore-ester-7 and tri- methyl borate was evaluated in laboratory bioassays against Coptotermes acinaciformis (Froggatt). Seasoned sapwood blocks of Pinus radiata D. Don, and Eucalyptus regnans (F. Muell) were impregnated with the various borate compounds. There were marked differences in mass loss and mortality rate of the termite used in the bioassay units for different boron retentions. After 8 weeks the result suggested that, borate was toxic to termites in laboratory bioassay even at 0.20% m/m BAE and caused significant termite mortality. However, termites were not deterred from attacking the borate treated timber at higher retentions of > 2.0% m/m BAE. These laboratory results indicated that the minimum borate treatment required to protect timber against termites attack and damage was > 1.0% m/m BAE.
B M Ahmed, J R J French, P Vinden


Decay and mold resistance of borate modified oriented strandboard
2003 - IRG/WP 03-40260
Decay and mold resistance of zinc borate (ZB) and calcium borate (CB) modified oriented strandboard (OSB) from southern mixed hardwoods and yellow pine was investigated in this study. Tests were done with brown rot, Gloeophyllum trabeum, and white-rot, Trametes versicolar, fungi for 8 and 12 weeks, respectively. Wood species and fungus type had significant influence on the decay resistance. Decay caused by brown rot was evident for all untreated southern pine and mixed hardwood OSB controls. White rot, however, did not cause significant sample weight loss for both species groups. The incorporation of ZB and CB into the OSB provides suitable protection against brown- and white-rot fungi. No significant weight loss was observed from the treated OSB. Microscopic analysis shows that the hyphae were abundant in wood rays and cell walls in the southern pine OSB controls attacked by G. trabeum. Untreated samples from mixed hardwoods and commercial OSB were most susceptible to mold growth. The borate-modified OSB from mixed hardwoods and southern pine effectively prevented the mold growth. Mold resistance was achieved with increase of borate retention level in the samples. Mixed hardwoods OSB showed a higher susceptibility to mold growth than southern pine OSB with or without borate treatment.
Q Wu, S Lee, J P Jones


Durability of Wood Plastic Composites Relative to Natural Weathering and Preservative Treatment With Zinc Borate
2005 - IRG/WP 05-40316
Wood-Plastic Composites (WPCs) used for decking have experienced dramatic increases in North America, averaging 25% growth per annum since 1998. A key factor contributing to this growth has been the successfully communicated message that they are "virtually maintenance free". The common perception being that the wood fiber is completely encapsulated by the thermoplastic resin, minimizing the potential for moisture absorption and inhibiting attack by wood destroying organisms. Recent publications, however, have raised concerns about the durability of WPCs. These studies showed that wood particles close to the surface of WPC products can attain moisture levels high enough to facilitate the onset of decay. Other experiments have shown that preconditioning this material through accelerated laboratory weathering (QUV) or natural exterior exposure to the elements, yielded significant increases in moisture uptake relative to the unexposed samples. The ability of these materials to absorb moisture has been identified as a significant factor in evaluating decay susceptibility in these laboratory tests. We examined moisture uptake in large sized (low surface to volume ratio) and smaller cut (high surface to volume ratio) WPC samples and found a much greater and rapid water uptake in the smaller samples. A soil block decay test with commercially produced unweathered WPC’s resulted in weight losses of between 10-20% (20-40% wood component) in as little as four months time. Effects of exterior weathering on moisture uptake showed increased moisture in samples taken from WPC boards in the field at various locations for 1 to 2 years. A soil block decay test with unweathered and naturally weathered WPCs showed significantly high weight loses in samples that had been in an outdoor exposure in Valencia, Ca for 2 years. Samples from the same exposure test that had been treated with 1.0 or 2.0 % zinc borate showed almost no weight loss.
M E Mankowski, F M Ascherl, M J Manning


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