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The rate of redistribution and loss of leachable preservatives under service conditions
1993 - IRG/WP 93-30026
This paper describes experiments carried out to determine patterns of preservative redistribution and any associated losses which occur when wood containing unfixed water-soluble wood preservatives is exposed to service conditions where leaching is possible. Scots pine sapwood treated with disodium octaborate was used as a model system. Results are recorded and discussed for trials representing painted joinery out of ground contact and unpainted stakes half buried in the ground. The results indicate that in the painted samples out of ground contact the water-soluble compound was redistributed longitudinally and away from the joint zone during the first months of exposure, although little redistribution occurred laterally. No difference in redistribution patterns could be associated with paint type. Ground contact stakes showed a loss in the water-soluble compound of about 40% in the first six months exposure. Most of this appeared to occur from the surface zones of the stake exposed to the weather, particularly from the extreme top. In addition, the compound appeared to migrate upwards from the below-ground portion of the stake to the above-ground portion. These results provide new information on the extent of movement of water-soluble preservatives in painted, jointed timber out of ground contact and in unpainted timber in ground contact. It is concluded that the long-term significance of the observed redistribution effects for painted joinery should be evaluated to confirm that there is no likelihood of shortcomings in performance in practice. For the ground contact situation, results confirm that rates of redistribution and loss are high enough to indicate inappropriateness of such materials for practical use without associated technologies to reduce mobilities.
R J Orsler, G E Holland


The hydrolysis of organo-boron compounds in treated particleborard
2000 - IRG/WP 00-40180
Standard particleboard (manufactured for interior applications) was treated with trimethylborate and modified trimethylborate and then left to hydrolyse for specified periods. The percentage residual trimethylborate was determined by placing samples in kerosene and analysing the kerosene for boron after 3 days of leaching. There was a significant correlation between the percentage hydrolysis of trimethylborate and the original trimethylborate concentration in the wood. The specific gravity of modified trimethylborate formulations also influenced the apparent rate of hydrolysis.
K M Filcock, P Vinden


Natural exposure weathering tests: Their role in the assessment of wood preservative efficacy
1993 - IRG/WP 93-20006
Previous work has demonstrated the potential and usefulness of natural ageing procedures in e evaluation of wood preservative efficacy. This results from the combination of physico-chemical influences and microbiological interactions with both substrate and wood preservative. In this paper, results are presented for a range of biocide types. Discussions are centred on the value of natural exposure weathering tests for preservative efficacy assessment and the importance of biological persistence in the design of effective wood preservatives.
G R Williams, J Brown


Leaching characteristics, decay and termite resistance of treated wood with boron compounds, N'-N-(1,8-Naphthalyl) hydroxylamine (NHA-Na), and hydroxynaphthalimide (NHA-H)
2003 - IRG/WP 03-30307
Despite many advantages of boron wood preservatives, boron itself does not adequately protect wood in ground contact and exterior applications because its natural diffusibility and susceptibility to leaching. As a result of previous studies to limit or decrease boron leaching, several fixation systems have been developed. In this study, we evaluated the effects of N'-N-(1, 8-Naphthalyl) hydroxylamine (NHA-Na) and hydroxynaphthalimide (NHA-H) on boron leaching and decay and termite resistance via boron precipitation in wood after NHA treatments at varying concentrations. Wood blocks were treated with disodium octaborate tetrahydrate (DOT), boric acid (BA) NHA-Na or NHA-H solutions. Preliminary results showed treatment of wood blocks with DOT, boric acid, and calcium borate and 1% or 0.1% NHA-Na solutions in sequential processes appears to somewhat reduce the susceptibility of boron to leaching. Blocks treated sequentially with boron compounds and then 1% NHA-Na solutions showed about 30% less boron leaching. In addition, the existence of boron and NHA in wood together showed a synergetic effect against wood degrading organisms and termites. We conclude that precipitation of NHA at higher concentrations decreases or limits boron leaching. On the other hand, the relationship between boron and NHA concentration in wood as regards precipitation possibilities appears to be predictive for reducing boron leachability.
S N Kartal, Y Imamura


Effect of boron compounds-furfuryl alcohol treatment of wood on dimensional stability, termite resistance and boron leachability
2001 - IRG/WP 01-40195
Sapwood blocks of Japanese cedar (Cryptomeria japonica) and Caribbean pitch pine (Pinus caribaea) measuring 20 (tangential) x 20 (radial) x 10 (longitudinal) mm were impregnated with furfuryl alcohol (FFA) by a vacuum-diffusion process followed by curing under heating. Boron compounds (boric acid, ammonium borate and ammonium biborate) were mixed in the impregnation solution of FFA. Anti- swelling efficiency, water holding capacity and moisture exclusion efficiency were measured. Boron leachability was determined by ion chromatography with ten leaching cycles according to JIS 9201 (1992). The specimens were exposed to termite attack testing, before and after the cyclic leaching process. The results indicated that FFA imparted to wood greater dimensional stability when mixed with boron compounds. Boron when mixed with FFA behaved differently to boron alone treatment, although it was still leachable. The wood specimens treated with FFA-boron compounds were quite resistant to termites even after severe leaching.
S K Ozaki, M K Yalinkilic, Y Imamura, M F Souza


The emission of boron compounds from treated particleboard
2000 - IRG/WP 00-40179
The emission of chemical vapours can be harmful both during treatment and service of wood and wood products. Samples of Standard particleboard (for interior use) were treated with trimethylborate, and a number of modified organo-boron compounds. Treated samples were placed immediately under a desiccator lid and air was drawn across each samples to 3 water traps. Water samples were taken after 30, 60, 120 and 180 minutes and tested for elemental boron content. Samples treated with trimethylborate emitted the greatest amount of boron into the water traps recording 434.8 mg/L after 30 minutes reducing to 144.4 mg/L after 180 minutes. Samples treated with modified organo-boron compound showed negligible boron emissions and samples treated with mixtures of trimethylborate and modified organo-boron compound emitted 35.1 mg/L boron after 30 minutes increasing to 362.5 mg/L after 180 minutes. The results show that samples containing trimethylborate have much higher emissions of boron over the 180 minute period.
K M Filcock, P Vinden


Removal of copper, chromium and arsenic from CCA treated wood using boron compounds
2005 - IRG/WP 05-50230
This study evaluates the copper (Cu), chromium (Cr) and arsenic (As) removal from CCA treated wood using boron compounds such as boric acid, borax (sodium tetraborate), and Timbor (DOT, disodium octaborate tetrahydrate) at varying (3 and 5%) concentrations. Remediation processes were taken at 1, 5 and 10 day intervals. Metals in remediated chips or sawdust were then analyzed using ICP and XRF. Results showed that, higher level of Cu was removed followed by As and Cr. The percentage removal of metals was higher in saw dust then chips. Borax at lower concentration (3%) removed 41.4%, 18.3% and 44.9% of Cu, Cr and As, respectively, in 10 days while at higher concentration (5%) 65.8%, 55% and 55.8% of Cu, Cr, As, respectively, were removed for the same period. Boric acid removed 39.7%, 15.5% and 35.6% at lower and 50.7%, 48.9% and 50.9% of Cu, Cr, and As at higher concentration, respectively, while DOT was not an effective extractant. Distilled water extraction removed 27.3%, 23.7% and 22.8% of Cu, Cr and As respectively. In case of chips, borax removed 30.3%, 19.7% and 24.9% of Cu, Cr, and As; boric acid removed 25.5%, 12.2% and 19.5%; DOT removed 22.8%, 10.8%, 14.2% and distilled water 17.7%, 11.1% and 10.2% of Cu, Cr, and As, respectively. Increasing the concentration of solution has greater effect on elements removal. Among the three compounds tested, borax removed higher levels of metals compared to boric acid and DOT.
B Tarakanadha, T Hata, S N Kartal, W J Hwang, Y Imamura


Development of threshold values for boron compounds in above ground exposures: Preliminary trials
1998 - IRG/WP 98-30179
Boron is increasingly used both as an initial and remedial treatment for protecting wood against fungal and insect attack. While establishing lethal dosages for boron against insects through feeding tests is relatively simple, establishing thresholds for fungal attack poses more of a challenge. Tests using boron dispersed in agar artificially surround the fungus with both boron and excess nutrients and poorly replicate the wood matrix. Soil or agar block exposures more closely replicate exposure, but these tests also expose the wood to leaching and employ large masses of actively growing fungal mycelium. In practice, however, fungal attack may be initiated by either spores or hyphal fragments that may be far more sensitive to boron. In an effort to develop more accurate thresholds for boron in wood exposed in non-soil contact, we evaluated the ability of hyphal fragments of two fungi, Gloeophyllum trabeum and Trametes versicolor to colonize and decay sapwood and heartwood blocks of Douglas-fir (Pseudotsuga menziesii) treated to retentions between 0.03 and 0.46% boron oxide (wt/wt) in modified petri dish tests. As expected, weight losses were lower in untreated heartwood samples, reflecting the moderate durability of Douglas-fir heartwood. Thresholds for sapwood and heartwood for both fungi were between 0.08 and 1.0% BAE and there appeared to be little effect of the heartwood on the resulting toxic threshold values for boron. These values illustrate the sensitivity of hyphae to boron and imply that higher concentrations may not be necessary for protecting wood from fungal attack in true above ground exposures protected from rainfall.
J J Morrell, C M Freitag, S Unger


Bibliography on the use of boron compounds for the preservation of wood
1973 - IRG/WP 315
This bibliography is based on an earlier literature survey prepared by J. Thornton and Wm. E. Bruce (O.E.C.D. Document No. 27/DAS/CSI/M/91) which was enlarged and revised for a meeting in Paris in October 1968 (Document 27/DAS/CSI/M554) by Professor W. Bavendamm of Reinbek. The latter (1968) document with its 166 references has now been extended and brought up to date. Acknowledgments are due to Borax Consolidated Ltd. and to the New Zealand Forest Research Institute who have both helped by providing us with further compilations of their own. Boron compounds have been in use in the past and are still found useful in medicine in the form of boric acid solutions and boracic ointment. They have also been used for the conservation of foodstuffs. In the treatment of wood they were first mostly used as fire retardants. Since the Second World War they have become increasingly important in the field of wood preservation.
R Cockcroft, J F Levy


Borates as wood preserving compounds: The status of research in the United States
1989 - IRG/WP 3542
This paper describes the extensive, on-going cooperative research effort among government and university research laboratories and industry to fully evaluate the potential for borates as wood preservatives in the United States. Research is discussed in terms of laboratory evaluations, field testing and mill trials, pilot plant pressure treatment studies, and remedial treatments. Future research plans are also presented.
H M Barnes, T L Amburgey, L H Williams, J J Morrell


A new process for in situ polymerization of vinyl monomers in wood to delay boron leaching
1998 - IRG/WP 98-40110
Efforts were accelerated on effective use of boron compounds in wood preservation owing to their environmentally safe characteristics and relatively low costs in addition to their well-known high bioactivity and fire resistant properties. Although having these unique favorable properties, they are readily leachable from treated wood at humid conditions. Therefore, they had limited market for exterior applications. A supplementary combination treatment with vinyl monomers; styrene (ST) and methylmetacrylate (MMA) was studied in order to extend the service life of boron treated wood. Sapwood specimens of Japanese cedar (Cryptomeria japonica D. Don) first treated with boric acid (BA) at 1.00% aqueous solution concentration. Vinyl monomers were impregnated after air-drying of BA-treated wood at ambient temperatures. Polymerization was performed during compression of monomer impregnated wood to a 50 to 70% dry set of radial dimension under a hot-press heated to the polymerization temperatures of 60 and 90°C required by the selected catalysts VAZO (a, a' - Azobis-isobutyronitrile) and benzoyl peroxide, respectively. Wood acquired a perfect dimensional stability and remarkably high moisture exclusion efficiency with the minimum water holding capacity with the compressed-wood polymer composite (CWPC) process that was approved by submerging of the test specimens in tap water, boiling water exposure to a 10 cycles accelerated severe weathering. As a result, boron leaching rate from CWPC pretreated with BA was considerably slower than that from ordinary WPC. Scanning electron microscope (SEM) observations were found explanatory for controlled-but-continuous boron leaching determined analytically. An effective bulking was found necessary to accompany to polymerization in cell wall with an even distribution of monomer in wood. Grafting to cell wall components can be tried further to achieve an envelop polymerization of boron deposited sites in WPC for better boron immobility.
M K Yalinkilic, W Dwianto, Y Imamura, M Takahashi


Diazenes and some organic complexes of boron as potential fungicides for preservation of wood
1999 - IRG/WP 99-30197
Screening for fungicidal activity represents the first step in searching for new active components with enhanced environmental profile in comparison with traditional wood preservatives. Diazenes, their salts, and the salts of the corresponding semicarbazides, as well as several complexes of boron, were screened for fungicidal activity against wood decay fungi Trametes versicolor, Coniophora puteana and Poria monticola. Activity was exhibited by two diazenes and two salts - tetrafluoroborates. Efficacy of both tetrafluoroborate derivatives was additionally confirmed by a mini-block test. In comparison with diazenes, substances from the group of boron complexes with 1,3-dicarbonyl compounds showed enhanced fungicidal activity.
M Petric, B Paradiz, J Stern, F Pohleven, S Polanc, B Stefane, R Lenarsic


Addition of boron compounds and octanoic acid for improvement of biocidal properties and copper fixation at copper-ethanolamine based wood preservatives
2006 - IRG/WP 06-30408
Copper-ethanolamine based wood preservatives became important active substance (formulation) for wood protection, novelty. As copper itself can not ensure sufficient protection against wood destroying organisms and fixation in wood we combine it with other biocides like ethanolamine, boron and octanoic acid. This investigates were performance on spruce wood impregnated with different combination of copper-ethanolamine, boron and octanoic acid in aqueous solution. Copper fixation was determined according to the modified ENV 1250 standard method, while fungicidal testing against Trametes versicolor, Gloeophyllum trabeum and Antrodia vaillantii were performed according to the mini block procedure and termiticidal activity was determined using Kalotermes flavicollis. The results showed that addition of boron increases copper leaching, but on the contrary improves efficacy against wood decay fungi and termites. On the other hand, addition of octanoic acid improves copper fixation, and slightly decreases effectiveness against copper tolerant fungi.
F Pohleven, M Humar


The response of the Formosan subterranean termite (Coptotermes formosanus Shiraki) to different boron compounds
2007 - IRG/WP 07-10609
Although boric acid and other boron compounds have been used since the 1800s as insecticides, their mode of action is not well understood. Borate salts, in particular sodium and zinc formulations, are effective wood preservatives and are used extensively in Hawai’i to protect building materials from both drywood (Kalotermitidae) and subterranean (Rhinotermitidae) termites. The Formosan subterranean termite, Coptotermes formosanus Shiraki, is the most important insect pest in the state, causing over $100 million in prevention and repair costs. In order to determine whether different borate salts elicit different responses in C. formosanus, termite workers (undifferentiated individuals) were collected from field colonies maintained in Honolulu, Hawai’i, and exposed to composite board samples of different borate salt formulations in the laboratory. The treatments included zinc borate (ZB) (0.88% and 0.18%), disodium octaborate tetrahydrate (DOT) (ZB and DOT in a 60/40 and 80/20 ratio), anhydrous boric acid (B2O3) (60/40 and 80/20 ZB/B2O3), and an untreated composite board control. Activity and mortality data were recorded over a 4-week period; results suggest the concentration of boron in the wood sample, rather than the associated salt, has a greater impact on termite feeding, and that anhydrous boric acid reduces termite feeding more rapidly than the other formulations tested. Inductively Coupled Plasma - Atomic Emission Spectrometry (ICP-AES) was used to determine boron ingestion after five days of exposure to high-concentration (ZB 0.88%, 60/40 ZB/DOT or 60/40 ZB/B2O3) boron treated timber. DOT consumption resulted in slightly higher boron concentrations than B2O3 (324.2 and 306.3 mean ?g/g boron, respectively), and ZB 0.88% (170.0 ?g/g) was intermediate between those two treatments and the control (30.2 ?g/g). The DOT and B2O3 treatments were an order of magnitude greater than the composite board control.
M C Gentz, J K Grace


Leaching performance, decay and termite resistance of wood treated with boron compounds incorporated with phenol-formaldehyde resin
2009 - IRG/WP 09-30503
A resol-type phenol-formaldehyde (PF) resin was synthesized and designed to penetrate wood incorporated with boron compounds in order to immobilize boron in wood. The leaching performance, decay and termite resistance of treated wood was investigated. Three kinds of boron compounds, that is, boric acid (BA), borax (BX) and disodium octaborate tetrahydrate (DOT), were selected to mix with PF and two species of wood (Chinese fir and Masson pine) were selected as the treating samples. The leaching process of boron from wood blocks was performed according to the American Wood Preservation Association (AWPA) standard E11-06. And the boron content in treated wood and leachates were determined by inductively coupled plasma optical emission spectrometer (ICP-OES). The results showed that boron leaching was reduced markedly and negligible boron was leached in some treatments. In laboratory termite tests against Coptotermes formosanus Shiraki, treated wood showed low weight loss. In addition, in laboratory decay test using a brown-rot fungus (Gloeophyllum trabeum) revealed that the decay resistance of PF-boron treated wood was also greatly improved.
Liping Yu, Jinzhen Cao


Biological Performance of Boron-based Chemicals Treated Wood Composites
2009 - IRG/WP 09-40464
In this study, the biological performance of wood-based composites panels treated with boron containing chemicals against to a fungus was determined. Boric acid, borax, zinc borate and agricultural borate (Tarım-bor™), developed and patented by National Boron Research Institute, were mixed with wood chips or fibers and then particleboard, medium strand board and middle density fiberboard were produced. The decay tests of these wood composites were done according to the soil-block test. Among the boron compounds, zinc borate demonstrated better resistance against to C. puteana fungus than other boron compounds used in this study. According to the durability classification, MDF was better than particleboard and MSB.
Ü C Yıldız, H Kalaycıoğlu, S Yıldız, A Temiz, E Tomak Dizman, A Çavdar Dönmez


Sorption properties of wood impregnated with aqueous solution of boric acid and montan wax emulsion
2010 - IRG/WP 10-40492
Non-biocidal techniques for wood protection become more and more important, nowadays. One of the possible treatments is use of water repellents. In the present research influence of, one of the possible water repellent, the montan wax emulsion, on the moisturizing and the sorption characteristic of impregnated wood was investigated. To achieve a better protection against wood decay fungi, montan wax emulsion enriched with boric acid, was used for impregnation of wood. The equilibrium moisture content (EMC) during the adsorption and the desorption process at five levels of relative humidity (φ1 = 20%, φ2 = 33%, φ3 = 65%, φ4 = 88% and φ5 = 98%) was monitored. Water repellence efficiency was monitored in the chamber with high relative air humidity (87%) and during dipping in the water. Impregnated samples were also exposed outdoor in cowered position for five months. The results showed that the sorption properties of the impregnated wood are strongly related to retention of preservative solutions after impregnation and its compositions. Montan wax reduced equilibrium moisture content of the impregnated wood up to 25% while specimens impregnated with combination of montan wax and boric acid in some cases resulted in the decreased and in some cases in the increased EMC. The Guggenheim-Andersen-deBoer (GAB) model of sorption isotherms was fitted to experimental data to explain the sorption mechanisms.
B Lesar, M Humar


Influence addition of boron compounds to adhesives on the bonding quality and fungicidal properties of glued wood
2010 - IRG/WP 10-40497
Wood is one of the most important construction materials. However, users of wood face two issues: limited dimensions and insufficient durability. These issues have been overcome with the development of bonding and wood preservation. The preservation of glued wood is elucidated in this paper. Through the addition of boric acid to adhesives, we tried to improve the fungicidal properties of glued wood. The results of mechanical testing (shear strength and delamination) showed that the addition of boric acid to glue did not have a negative impact on the performance of the glued wood. On the contrary, some properties were even improved. Unfortunately, the addition of boric acid to impregnated wood does not improve the resistance of the glued wood to brown rot fungi.
M Humar, B Lesar, A Ugovsek, M Kariz, P Kralj, M Šernek


Effect of P/F ratio, PF concentration and treating method on boron leaching from wood treated with PF modified boron compounds
2011 - IRG/WP 11-30559
In order to immobilize boron in wood, three kinds of resol-type phenol-formaldehyde (PF) resin with different P/F ratios were synthesized in laboratory and incorporated with three types of boron compounds to treat wood. The used boron compounds included boric acid (BA), borax (BX) and disodium octaborate tetrahydrate (DOT). The leaching test of boron from wood blocks was performed according to the American Wood Preservation Association (AWPA) standard E11-06. The boron content in treated wood blocks and leachates were determined by inductively coupled plasma optical emission spectrometer (ICP-OES). The results of experiment indicated that higher PF concentration is preferable for better boron fixation. There was no significant difference between the three boron compounds used in this experiment with only slightly higher boron leaching for borax. The “Two-step method” showed lower boron leaching than “One-step method”, which may be due to the lower boron retention before leaching caused by the boron leaching during PF impregnation process. Considering the P/F ratio, PFB (P/F ratio: 2.0) and PFC (P/F ratio: 2.2) showed a little lower boron leaching than PFA (P/F ratio: 1.6).
Liping Yu, Jinzhen Cao


The case for using borates in termite control in tropical Australia
2011 - IRG/WP 11-30573
A brief historical overview of boron based wood preservatives efficacy against subterranean termite management worldwide, and in Australia, is presented. The boron based compounds to be used in H2 hazard conditions, may be applied as a surface treatment by dip, flood coat or spray, and rapidly penetrates to the centre of timber substrates, whether containing sapwood or heartwood. However, section 8, clause 8.2.2 (c) of the Australian Standard AS 1604.1-2010 bans the use of boron compounds for use in termite management north of the Tropic of Capricorn. In this paper we argue the case for the adoption of boron compounds in termite management systems north of the Tropic of Capricorn, as either single or multi-component biocide systems. We have searched the numerous papers for “boron and termites” in the IRG data base since 1969 to the present, and other scientific evidence from a consistent science worldview; our own results of boron against termites in our ‘whole-of-house’ above-ground and in-ground field test using simulated houses and wood stakes respectively at Nhulunbuy, Arnhem Land, in tropical Australia. In these test sites, active populations of Coptotermes spp., Heterotermes spp., Nasutiterme spp., Schedorhinotermes spp., and Mastotermes darwiniensis, were present. After 5 years in the ‘whole-of-house’ above-ground trial and 2 years of the in-ground trial, no termite damage has occurred to boron-treated timbers. Furthermore, we refer to analytical data by two NATA certified laboratories in Brisbane of the Tru-Core® Timber Preservation Process which was applied as a spray treatment from a mobile unit. This system is a boron-based multi-component biocide system, incorporating glycol borates, deltamethrin, permethrin and the fungicide propiconazole, that surpassed all the minimum requirements of AS 1604.1-2010 for the H2 status, even penetrating the heartwood of radiata pine and oregon. While, this standard does not specify the methods of preservative treatment that may be adopted to achieve the specified penetrations and retentions. It states that the standard is only intended for application in approved industrial treatment plants. In the current climate of extreme environmental challenges out standards need to broaden the scope of protection and treatment and also consider the new generation of biocides are different than the traditional wood preservatives. Standards specify the minimum requirements of a preservative to protect timber from attack and damage from termites and the document must encourage innovative systems for access into the industry and the protection of structural timbers.
B M Ahmed (Shiday), J R J French


Smart hydrogels from low molecular weight amphiphilic compounds: toward a solution to decrease leachability and increase efficacy of boron preservatives?
2012 - IRG/WP 12-30589
A new catanionic system associating amphiphilic carnosine (AlaHisC8) and lauric acid forms supramolecular hydrogel at very low concentration. This gel was investigated and we have checked the validity of the concept of hydrogels utilization to reduce boron leachability and to develop new wood protection treatments. Impregnation with 5% aqueous borax solution (w/w) and 0.3% gelator agent (w/w) allows to improve resistance of Scots pine sapwood subjected to water leaching towards the brown rot fungus Poria placenta, while samples treated with 5% aqueous borax solution were partially degraded by the fungus. These results clearly indicate the effectiveness of hydrogel to retain boron in wood.
F Obounou Akong, P Gérardin, C Gérardin-Charbonnier


The Effects of Industrial-Scale Heat Treatment and Impregnation with Boron Compounds on Water Uptake and Tangential Swelling of Some Wood Species
2012 - IRG/WP 12-40599
This study evaluated the effects of boron impregnation and heat treatment on water uptake and tangential swelling of spruce (Picea orientalis), pine (Pinus nigra), beech (Fagus orientalis) and poplar (Populus deltoides) wood species. The samples (10 x 5 x 40 - tangential x radial x longitudinal cm) were impregnated with 4 % boric acid and 4 % borax according to the ASTM D-1413 standard method. After the impregnation, heat treatment was applied on the impregnated test samples in an industrial plant, at four different temperatures and two different durations under steam atmosphere. Soft wood and hard wood samples were subjected to the heat treatment at 212 °C - 220 °C, and at 180 °C - 190 °C, respectively, for 90 and 120 min. Heat treated and impregnated test samples were reduced smaller sizes (3 x 3 x 1.5 cm - tangential x radial x longitudinal) for water uptake and tangential swelling tests. The tests were carried out based on TS 2472. Results indicated that the highest retension was 26.9 kg/m3 in pine wood samples impregnated with BA (26.93 kg/m3). Hardwood retention was lower than soft wood retention. In generally, water uptake and tangential swelling ratios of only heated samples was found lower than non-treated control samples.The combination of heat treatment and BX impregnation was negatively affected water uptake especially in spruce and poplar wood. Borax was more hygroscopic than boric acid. The tangential swelling rates of four wood species impregnated with boric acid and borax were found lower than the non-treated control samples. The tangential swelling rates of spruce and pine wood samples impregnated with boric acid decreased compared to the only heated samples. Heat treatment process significantly affected the remaining boron compounds in wood. Although the steam atmosphere in the oven during the heat treatment, the amount of boron leached from wood was low especially in BX treatment.
A Can, S Yildiz, Ü C Yildiz


Termite resistance of wood impregnated with phenol-formaldehyde (PF) modified boron compounds
2012 - IRG/WP 12-30604
In order to investigate the effect of phenol-formaldehyde (PF) modified boron compounds on termite resistance of two main plantation-grown wood species, namely, Masson pine (Pinus massoniana Lamb.) and Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), laboratory termite tests and field tests were carried out according to AWPA standard E1-97 and AWPC protocols/2007. Different concentrations of boric acid (BA), borax (BX), and disodium octaborate tetrahydrate (DOT) mixed with 20% aqueous solution of PF were used to impregnate the sapwood of both wood species. Formosan termite (Coptotermes formosanus Shiraki.) was used as the test termite in laboratory termite tests, while the field tests were carried out in Guangzhou, China. The results showed that the compound treatments of boron compounds with PF could efficiently improve the termite resistance of both wood species, especially the treatments by using BX. According to the laboratory termite tests, the untreated Masson pine and Chinese fir sapwood rated 5 and 4 (seriously attacked) with average weight losses of 29.3% and 43.7%. After treated with PF modified boron compounds with concentrations of 0.5, 1.0, 1.5, and 2.0%, the average weight losses were reduced to lower than 5.9, 5.1, 2.3, 1.2% for Masson pine and 7.6, 5.0, 1.8, 1.1% for Chinese fir, respectively. The performance of Masson pine in field test was much worse than Chinese fir by showing complete digestion by the termites. BX-PF treatment showed the best results in field test by reducing the average weight loss of Masson pine samples from 100% to lower than 6.1% or Chinese fir from 25.6% to lower than 8.6% at a BX concentration lower than 1.0%.
Jinzhen CAO, Liping YU, Xuexiang HE


Aspects of diffusion of boron through wood
1984 - IRG/WP 3298
Boron compounds have been shown to be toxic to a wide range of wood destroying insects and fungi. They are cheap, have low mammalian toxicity and their application in the treatment of wood does not demand specialized equipment. These attributes make them specially attractive to developing countries. Currently, however, little is known about the mechanism of diffusion of boron through wood. Effective treatment with boron preservatives requires good understanding of how the preservatives diffuse through wood. This paper presents a research proposal with the overall objective of determining the relative importance of structural wood components in determining diffusion rates.
S Iddi


Utilization of curcumin for detection of presence of boron in wood
1982 - IRG/WP 3191
It has been shown that curcumin is not a reliable reagent for detecting boron in wood that has been attacked by fungi
M-L Edlund


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