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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


Leachabilty and efficacy of fatty acid derived boron esters as wood preservatives - leachability and efficacy of fatty acid derived boron esters as wood preservatives
2004 - IRG/WP 04-30351
Borates have many advantages as wood preservatives. However, boron is susceptible to depletion under humid conditions and this restricts its outdoor use. In order to reduce boron leachability in treated wood, one of the anticipative approaches is to use organic fixed boron-based preservatives. This study investigated the leachability of six boron ester compounds as potential preservatives. Scots pine sapwood (Pinus sylvestris L.) test specimens were vacuum treated at different concentrations of BAE (Boric Acid Equivalent) of each boron ester active ingredient with and without 10% addition of commercial resin product. Stand-alone boron treatment using 1% BAE disodium octaborate tetrahydrate (DOT) is conducted as a reference. The results of chemical analysis of leachates taken at different periods showed significant differences in boron leachability between the DOT treated samples and specimens treated with both boron esters. Although there are significant differences between the pure boron treatment and the resin protective addition treatment, minor differences were found between boron ester treatments irrespective of resin addition. However, these data allowed the selection of one boron ester compound for further biotesting based on its leaching performance. Results of the biological assays with both Scots pine sapwood and poplar (Populus trichocarpa x deltoides) samples using the European standard EN 113 confirmed the efficacy of the selected boron ester compound against Coriolus versicolor, Coniophora puteana, Gloeophyllum trabeum and Poria placenta. After sixteen weeks of exposure to fungal attack all specimens treated with the new organic boron compound at 0.66 % BAE, irrespective of resin addition, exhibited insignificant mass loss for all four fungi and both wood species tested, which proved the decay resistance of the treated wood.
A Mohareb, J Van Acker, M Stevens


Treatment of wood with boron esters
1995 - IRG/WP 95-30087
The treatment of wood and wood products with boron esters is reviewed. The physical and chemical characteristics of boron esters affecting the treatability of wood are discussed, in particular thermal decomposition and rates of hydrolysis. The uses and methods applying boron esters as wood preservatives include: (i) Solutions of boron esters for remedial and diffusible treatment of wood; (ii) solid boron esters for remedial treatments; (iii) vapour treatments using low boiling points esters, for example trimethyl borate; (iv) solutions of boron esters for light organic solvent preservatives (LOSP) treatment.
J Romero, P Vinden, J A Drysdale


Preliminary testing of spiroborate esters as wood preservatives
2013 - IRG/WP 13-30614
Fungicide and insecticide properties of boric acid are known since 30’s of the last century, but high solubility and leachability of inorganic borates limit their use for only applications not directly exposed to liquid water. A number of attempts were made to fixate borate salts into the wood structure but this research topic is still up to date and undiscovered. Water insoluble organoboron esters were tested in laboratory scale as wood preservatives. Although affected by leaching, the studied spiroborate esters were highly efficient even at very low retentions.
D Panov, N Terziev


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


Strength loss associated with steam conditioning and boron treatment of radiata pine framing
1987 - IRG/WP 3438
The combined effect of included defects and wood moisture content on the strength loss of second rotation radiata pine framing following conventional steam conditioning is investigated. The green Modulus of Elasticity (MOE) is reduced by approximately 13% after steaming. When dried after steaming, however, neither the MOE nor MOR is significantly different from unsteamed dried controls.
M J Collins, P Vinden


Synergistic effect of boron on Streptomyces rimosus metabolites in preventing conidial germination of sapstain and mold fungi
1992 - IRG/WP 92-1565
We evaluated the synergistic effect of boron (4% BAE solution of Tim-Bor or 4% boric acid) on Streptomyces rimosus metabolites in preventing spore germination of sapstain and mold fungi using plate bioassay, Southern yellow pine and sweetgum block tests, and green pine log sections: sapstain -- Ceratocystis coerulescens, Ceratocystis minor, and Aureobasidum pullulans; mold fungi -- Aspergillus niger, Penicillium spp, and Trichoderma spp. Inhibition of spore germination in plate bioassay by metabolites with boron was more effective than without added boron. Treatment of wood samples with the mixture of boron and unconcentrated metabolites also resulted in the synergistic effect and completely inhibited spore germination of sapstain and mold fungi.
S C Croan, T L Highley


Insect resistance of preservative treated tropical plywood against Lyctus
1990 - IRG/WP 1453
Seven plywood types composed of tropical wood species, vulnerable to Lyctus, were treated with various commercial water-borne and oil-borne preservatives. A wide range of preservative retentions was obtained by treating boards with dip treatment, steeping, double-vacuum and vacuum-pressure impregnations. Selected samples were subsequently tested for their insect resistance against Lyctus africanus during 6 to 8 months according to European Standard EN 20. All control samples were attacked, except one Obeche plywood exhibiting only 50% attack. Water-borne preservative solutions containing arsenic, boron or fluoride could not prevent attack at common retention levels for interior use e.g. lower than 5 kg/m³. Quaternary ammonium compounds showed no insecticidal efficiency, up to 3 kg/m³. TCMTB at 1.5-1.7 kg/m³ proved to be able to reduce slightly the susceptibility for insect attack. Organic insecticides gave the best results, with nearly no attack for plywood treated with lindane or cypermethrin. In spite of a preservative uptake of 25 to 30 kg/m³, endosulfan only could reduce attack by 50%. Protection by permethrin at 0.1% a.i. required a retention of 28 kg/m³. Besides the fact that variability in wood species and composition of the plywood are leading to different retention levels, variation in penetration and distribution of a.i., and as a consequence to a different insect resistance of the impregnated boards, some poor results were directly related to inadequate insecticidal activity and/or concentration of a.i. in some commercial formulations for Lyctus control.
J Van Acker, M Stevens, M Pallaske


Non-pressure treatability of plywood by CCA, CCB and boron
2005 - IRG/WP 05-40295
Study on diffusibility and absorbability of CCA, CCB and boric acid in 3 mm thick 3-ply hardwood plywood at water saturated and air-dry conditions and dipped at same concentration (5%) and same duration of time (12 hours) revealed complete diffusion of all the preservatives at water saturated condition. Only the CCA-C was found absorbed by the plywood at air-dry condition. The rate of absorption and diffusion of CCA-C was found about 4.5 times higher than CCB and boric acid.
A K Lahiry


Leaching of the new boron based biocide from coated wood
2001 - IRG/WP 01-30267
We investigated leachability of the new boron based biocide - a complex of an amine and boric acid - from vacuum impregnated spruce wood samples. It was determined by the standard ENV 1250-2 procedure that the new biocide is susceptible to leaching so from the water borne as well as from the ethanol borne boron containing preservative treated wood. Leaching may be retarded by application of surface coatings. The ability of a surface finish to prevent leaching is correlated to its water vapour permeability.
M Petric, M Pavlic, F Cadez


CCA modifications and their effect on soft rot in hardwoods
1982 - IRG/WP 3201
Decay tests were carried out on wood samples treated with three waterborne compounds all identical in composition but applied in different forms. There were significant differences in the effectiveness of the treatments particularly as regards the control of soft rot.
S M Gray, D J Dickinson


Depletion of boron and copper from CCB treated test specimens using different leaching protocols
2004 - IRG/WP 04-50208
The objective of this study was to measure the depletion of inorganic wood preservative components regarding the proposed OECD guideline "Estimation of emissions from preservative-treated wood to the environment: laboratory method for wooden commodities exposed in the use class 4 and 5" as part of the project "Investigations concerning the influence of test parameters on the release of biocidal actives from treated timber in leaching tests". Pine sapwood specimens (50x10x150) were pressure impregnated with CCB according to European Use Class 4. Before leaching all samples were stores 4 weeks for fixation. In addition leaching tests were performed according to the European Standard EN 84 by means of EN 113 blocks. Parallel investigations were carried out between two laboratories to assess the repeatability and comparability of the methods. The results of chemical analysis of leachates taken at different time intervals show that similar depletion rates were determined for copper and boron independent on the leaching protocol used. However, the loss of copper as well as chromium in short term dipping experiments was often lower than the detection limit. Furthermore it can be stated that the difference between parallels was higher for the results which were obtained for the OECD guideline that EN 84. A comparison of both laboratory results indicate that a quite good repeatability is given in case of the CCB treated material.
E Melcher, R-D Peek, U Schoknecht, R Wegner


Water-based wood preservatives for curative treatement of insect-infested spruce constructions
1998 - IRG/WP 98-30171
On laying down sanitation measures for wooden constructions infested by wood boring insects, we must take into account static risks for the construction - and, thus, for the security of the user - as well as risks for humans and environment due to the chemical preservative compounds of the treated wood. Analyses on many roof constructions made with spruce (Picea abies L.) have revealed that Hylotrupes bajulus L. and Anobium punctatum De Geer have not the significance given to them for decennies. That often allows to replace solvant-based with water-based wood preservatives in old buildings, for the protection of humans and environment. Therefore, a method has been developed in Switzerland for testing wood preservatives with delayed curative efficacy against the house longhorn beetle. Like the European Anobium Standard EN 370 this method intends to prevent the emergence of Hylotrupes beetles. Laboratory tests with diverse water-based wood preservatives available on the market in Switzerland have shown that particularly boron and benzoylphenylurea derivatives containing products get a sufficient penetration in the wood and prevent the emergence of the beetles.
E Graf, P Manser, B Lanz


The long-term performance of boron treated joinery in service - A case study
2000 - IRG/WP 00-20208
Joinery treated with borates 23 years ago and in service in residential flats was surveyed and analysed for boron content. The levels of boron still present were sufficient to prevent decay. None of the windows surveyed showed any decay despite the fact that moisture and sapwood contents were conducive to decay.
D J Dickinson, R J Murphy


Reticulitermes lucifugus Rossi, and its damages in Turkey
1982 - IRG/WP 1152
The moist-wood termite, Reticulitermes lucifugus Rossi, is generally observed on the wood material which has a direct contact with the soil as trunks and fence stakes. It was reported to be found in some provinces in Turkey. The termite has been seen in these areas so far at the endemic level, but any considerable damage or epidemy has not yet been reported. Considerable damages were observed on the fibreboard stored under unsuitable conditions at Artvin fibreboard factory during the depression period of building sector in the years of 1980-1981.
O A Sekendiz


Boron treatments for the preservation of wood - A review of efficacy data for fungi and termites
1994 - IRG/WP 94-30037
Boron treatments have been used for many decades for protection of timber from biological attack and also as a fire retardant treatment. In recent years there has been an increased interest in boron treatments as an option for protection of structural timbers' e.g. timber framing used in termite risk areas. This paper reviews efficacy data for both fungi and termites relevant to this end-use.
J A Drysdale


Mould resistance of lignocellulosic material treated with some protective chemicals
1984 - IRG/WP 3294
Effectiveness of preserving lignocellulosic material against moulding by treatement with water solutions of commercial wood preservatives and mixtures of various inorganic salts was investigated and compared with the effectivenes of sodium pentachlorophenoxide and boric acid.
K Lutomski


Finite element analysis of boron diffusion in wooden poles
2003 - IRG/WP 03-40263
The problem of describing the migration of dissolved boron in wood is treated with special reference to the commonly used remedial treatment of wooden poles. The governing equations are derived and discussed together with some of the material parameters required. The equations are solved by the finite element method and finally, results showing the effect of different treatment strategies are presented.
K Krabbenhøft, P Hoffmeyer, C G Bechgaard, L Damkilde


Report of meetings of remedial treatments Sub-group held in Madrid, Spain during 27-28 April 1988
1988 - IRG/WP 3502
J N R Ruddick


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


Fire resistance of Alder wood treated with some chemicals. Part II. Effect of Other Chemicals on the Combustion Properties
2002 - IRG/WP 02-40235
Samples from alder wood (Alnus glutinosa (L.) Gaertn. subsp. barbata (C.A.Mey) Yalt.) were impregnated according to ASTM D 1413-88 with boron compounds (boric acid, borax, sodium perborate), vinyl monomers (styrene, methyl methacrylate), Tanalith-CBC, Phosphoric acid, Vacsol, Immersol, Polyethylene glycole (PEG-400) and their mixed solutions of chemicals in order to determine their combustion properties. The results indicated that inorganic boron compounds with aqueous solutions were very effective as fire retardant and reduced burning of some vinyl monomers at some extent such as styrene and methylmetacrylate when used as a secondary treatment chemical polimerized later on wood structure and phosphoric acid was also showed fire-reterdancy. Further studies are suggested on boron-vinyl monomers, and boric acid+borax with different concentrations by physical and chemical interactions in terms of fire reterdancy.
A Temiz, Ü C Yildiz


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


A new approach to the maintenance of wooden railway sleepers. (Second report)
1988 - IRG/WP 3492
The microenvironment and micro-ecology of wooden railway sleepers was investigated to assess their condition to determine the necessary treatment, repair and replacement criteria. In this report the efficacy of the secondary preservative treatment with solid boron rods is discussed and the development of an in-situ, nondestructive test method based on the creation and assessment of structural dynamic vibrations is described.
W Beauford, P I Morris, A M Brown, D J Dickinson


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