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The use of bifluorides-diffusion in remedial treatments
1983 - IRG/WP 3256
A description is given about the experience to date of a 14 years' development to bring bifluorides-diffusion from laboratory evaluation to commercial service application. The described treatment is an adjunct to good design and not a replacement for it. The process is also used with an injection method for the remedial treatment of premature decayed external joinery.
H F M Nijman


The dip diffusion treatment of tropical building timbers in Papua New Guinea
1972 - IRG/WP 310
In Papua New Guinea a dip diffusion process using a multi salt preservative developed by C.S.I.R.0. has been in commercial use for 8 years. Over 200 million super feet (236,000 m³ ) of timber has been treated during this period and current rate of treatment is 34 million super feet (80,400 m³ ) of timber per year in 70 licenced treatment plants. The process has been found to be simple to apply, convenient to control and has proved very successful in the protection of timber used out of ground contact and protected from the rain. No serious health hazards to process operators or product users have come to light. In common with other countries in the wet tropics P.N.G. is faced with very serious biological deterioration hazards to timber in houses but dip diffusion has overcome the major problems. During the 16 years in which dip diffused timber has been in service in P.N.G. there have been no notable falldowns, the only falldowns reported being in mouldings in which heavy dressing has removed the preservative envelope, but this is a very rare occurrence and cannot be considered of economic importance.
C R Levy, S J Colwell, K A Garbutt


Dip-diffusion of dressed timber - Effect of drying
1989 - IRG/WP 3509
The effect of drying on dip-diffused dressed freshly sawn timber was determined by the depth of penetration of boron achieved on the two test timber species, White cheesewood (Alstonia scholaris) and Light Hopea (Hopea papuana). The results obtained showed that light density White cheesewood was completely penetrated even after 3 days drying while Light hopea, treated immediately achieved 5.2 mm penetration after 2 days diffusion and subsequently better after 14 and 21 days diffusion. Adequate penetration was only achieved after 14 and 21 days diffusion when there was delay between 30 minutes and 72 hours.
H C Konabe


Boron treatment methods for lyctid susceptible hardwoods growing in Tasmania
1998 - IRG/WP 98-30168
A survey of existing boron plants that treat to protect hardwoods from attack by lyctids in Australia showed that hot and cold bath, and vacuum pressure impregnation (vpi), were the two most common methods employed. In experimental work, two of the treatment methods, vpi and dip diffusion, were used to treat seasoned and green messmate (Eucalyptus obliqua) and blackwood (Acacia melanoxylon). The treating solution in both cases was Diffusol. For vpi treatment, a solution of 2.5% boric acid equivalent (BAE) was used to treat rough sawn boards with a Bethell schedule. After treatment, boards were strip stacked on a pallet under cover, later cut in half, and the centres sprayed with turmeric reagent to reveal that all sapwood was adequately treated with boron. The solution for dip diffusion contained 12% BAE. Block stacked timber was dipped, wrapped, and stored to allow diffusion of the boron. All green E. obliqua and A. melanoxylon boards were adequately treated after dipping in Diffusol and two, four or six weeks diffusion. Some of the air dried A. melanoxylon boards could not be adequately treated by this method when diffusion periods were just two or four weeks. However, a six week diffusion period allowed full sapwood treatment of all boards.
L J Cookson, D Scown, K McCarthy


Dip-diffusion of dressed timber - Effect of drying
1990 - IRG/WP 3603
The effect of drying on BFCA dip-diffused, dressed, freshly sawn timber was determined by the depth of penetration of boron achieved on two test timber species, White Cheesewood (Alstonia scholaris) and Light Hopea (Hopea papuana). The results obtained showed that the light density White cheesewood was completely penetrated even after 3 days drying while Light Hopea, treated immediately achieved 5.2 mm penetration after 2 days diffusion and subsequently better after 14 and 21 days diffusion. Adequate penetration was only achieved after 14 and 21 days diffusion when there was delay between 30 minutes and 72 hours.
H C Konabe


Accelerated diffusion treatment of sawn Sitka spruce grown in the UK
1986 - IRG/WP 3395
The treatment of 'green' sapwood and heartwood of Sitka spruce by diffusion methods was investigated. Steam/dip treatment processes gave increased solution uptakes and depths of penetration of copper in comparison with a simple dip treatment. Further investigation is required to reduce diffusion gradients with copper based formulations and to improve the penetration of 'green' heartwood of Sitka spruce by diffusion methods.
R J Murphy, D J Dickinson


Dip diffusion treatments in the tropics. A preliminary report
1973 - IRG/WP 316
Diffusion treatments based on the use of boric acid alone or in combination with other preservatives are widely used in Australasia (see IRG/WP/310). As part of a general survey covering both temperate and tropical countries, a survey of diffusion treatments in South East Asia, Southern Asia and the South Pacific was carried out, and the results of this survey are reported here. The survey is far from complete as fewer than 30% of the laboratories contacted had replied to a questionnaire sent to them at the time of writing. However, the answers received clearly indicate that, apart from those countries receiving direct technical assistance from Australia and/or New Zealand, diffusion treatments are not being used for the preservative treatment of timber. However, most laboratories contacted expressed interest in diffusion and were either currently testing or planned to test dip diffusion methods.
C R Levy


Ambient-temperature borate dip-diffusion treatment of green railroad crossties
2011 - IRG/WP 11-40556
In the USA, borates are increasingly being applied prior to air seasoning and creosote treatment of railroad ties (railway sleepers). Borates are typically applied to green ties by vacuum pressure application at 1 to 10% disodium octaborate tetrahydrate (DOT) concentration or by traditional dip-diffusion treatments at elevated temperatures. Higher temperatures are used to maintain the 30 to 50% solution concentrations needed to deliver appropriate cross-sectional retentions with only a topical application. In our study, a thickened borate system similar to that developed in New Zealand in the 1970s for the treatment of framing lumber was investigated as a possible method for the treatment of the larger timbers used for rail ties. This paper reports on the penetration and retentions achieved with three wood species dip-treated green in DOT at ambient temperature in a high-concentration borate emulsion. In an initial test, freshly-sawn crosstie sections of three common wood species (sweet gum, red oak and white oak) were dipped for three minutes in one of five different concentrations (25-50%) of borate emulsion at approximately 10oC. It was found that dipping in a 30% concentration liquid provided weight retentions that approximated to American Wood Protection Association (AWPA) standard retentions (2.7 kg•m-3). In the subsequent study, tie sections dipped in 30% DOT liquid were stacked and stored outside, with moisture-barrier wraps or roof covers. Moisture content and boron retention and penetration were monitored over time. During 3 months of monitoring, 10-20% reduction occurred from the 65-75% initial moisture content. White oak samples had the lowest borate retention of the three species and gum had the highest. Penetration also varied according to wood species. The data suggest that an ambient temperature dip-diffusion treatment of green railroad ties with DOT could provide cost-effective creosote pretreatment with the additional benefit of protecting the wood during the air seasoning period.
Jae-Woo Kim, A M Taylor, C Köse


Steam accelerated borate diffusion: Optimizing dry tie treatment
2015 - IRG/WP 15-40713
A small laboratory study was carried out which demonstrated that dry wood dip treated in a high concentration borate solution could not be subsequently treated properly with oil borne copper naphthenate unless it was subsequently steam treated to accelerate borate penetration into the wood and re-dry the wood beforehand. A larger study with commercial sized cross ties (railway sleepers) was carried out to see if the same steaming approach could be successful in large dimensions, at a commercial treatment plant and with creosote. It was found that dry ties dip treated in a 25 % borate solution at ambient temperature easily met AWPA standard borate retention and railway specifications as determined by gauge and could then be subsequently and successfully creosote treated after a two hour steaming process. The steaming would not increase total treatment time in the cylinder as it could be considered part of the sterilization time and the treatment by dip had the advantage of treating all species approximately the same with regard to borate preservative retention, overcoming the weakness of pressure treating with borate which can reduce creosote penetration and retention by making the ties too wet and cannot properly treat the white oak and hickory ties to appropriate retentions when treated in the same charge as red oak ties. Some slight loss of borate seamed to occur as a result of steaming, as shown by assay, but the process was modified to avoid condensation in the process for full commercial adoption.
J-W Kim, J D Lloyd


Solvent drying and preservation of timber
1977 - IRG/WP 381
Processes which combine drying and preservation are first reviewed. Some preliminary experiments are then described in which blocks of green Sitka spruce sapwood were immersed, in a solution of tributyltin oxide (TBTO) in methanol at 60°C. Satisfactory penetration of the preservative and exchange of methanol and water occurred in a few hours. The methanol was removed rapidly from the wood by evaporation. Satisfactory penetration of TBTO into initially methanol-saturated samples occurred in a similar period. The factors influencing. such treatments are discussed. High initial moisture content of the wood and a high operating temperature are particularly desirable. Some aspects of the possible commercial operation of the process are discussed.
J A Petty


Sequestration of copper ions by the extracellular mucilaginous material (ECMM) of two wood rotting basidiomycetes
2004 - IRG/WP 04-10533
The radial growth rate of colonies originating from either whole or ECMM-free inocula of Coriolus versicolor was investigated. The presence of ECMM allowed colonies to maintain higher growth rates than those form ECMM-free inocula up to 2 mM CuSO4 in the medium. The ECMM of C. versicolor and G. trabeum was able to reduce the diffusion of copper ions in solution. The ‘raw’ ECMM of both fungi had a greater ability to reduce the diffusion of copper ions than ECMM which had been subject to dialysis to remove soluble, low molecular weight components. The ‘insoluble’ fraction of ECMM for both species was more effective than the ‘soluble’ fraction at reducing the diffusion of copper ions. It is concluded that ECMM confers some protection to hyphae against the toxic effects of copper ions on growth in vivo and that this due to the binding of copper ions to both the polysaccharide and to low molecular weight components of the ECMM
D Vesentini, D J Dickinson, R J Murphy


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


Performance of treated fence posts after 6 years in five test plots in the State of Sao Paulo - Brazil
1976 - IRG/WP 376
Fence posts treated with creosote, pentachlorophenol and creosote/ pentachlorophenol mixtures showed good performance after 6 years of exposure in five test plots located in the State of Sao Paulo - Brazil. Good results were also achieved with copper sulphate/sodium arsenate and copper sulphate/potassium dichromate mixtures. Fungi and termites were the main destroying agents found attacking the posts.
M S Cavalcante


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


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


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


Observations on the penetration of preservatives into green timber
1985 - IRG/WP 3335
Differences in the rate and extent of diffusion of MBT and NaPCP-based preservatives following a short dip treatment were observed. The importance of preservative distribution as well as toxicity to the target organisms in governing the ultimate performance of any anti-sapstain compound is discussed.
G R Williams, R A Eaton, D A Lewis


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


Preservative treatment of Eucalyptus saligna fence posts by the double-diffusion method
1982 - IRG/WP 3196
Eucalyptus saligna fence posts treated by the double-diffusion method with two chemical combinations showed average lives of 11.2 years (copper sulphate and potassium dichromate at 10.5 kg/m³ retention)and of 14.3 years (copper sulphate and sodium mono-H arsenate at 7.1 kg/m³ retention), as determined in five test sites in the State of Sao Paulo, Brazil. The exponential model was the best fit when expressing average life by the Decay Index (DI) as a function of time.
E S Lepage, A R De Freitas


Termite and decay protection - A superficial barrier field test
1983 - IRG/WP 3257
Samples of Pinus radiata were given a superficial barrier treatment and installed in the ground at two sites for five years to observe termite and fungal attack. The three best treatments of the series were Denso petroleum tape, Koppers hot dip tar enamel, and Arquad 2C/75 alkyl ammonium compound. As new fungicides and insecticides become available they are being added to the test using the same system of treatment and exposure.
R S Johnstone, W D Gardner


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


Fluorine compounds for wood preservation
1971 - IRG/WP 304
Fluoride compounds have gained a considerable importance in wood preservation, especially in Germany and some other countries of Europe. They are used as single compounde or in mixtures of different compounds. In the International Research Group on Wood Preservation which continues the activities of a former OECD-Group, it was moved to prepare a survey on fluorides in wood preservation together with other papers on the present state of knowledge of wood preservatives and methods of application. Monofluorides and silicofluorides have been used in the field of wood preservation for about 60 years and special development and application of hydrogen fluorides have been going on for 30 years. Much scientific work has been carried out on fluorides and much experience in practical use is available. It thus seems to be useful to briefly summarise the information on this group of compounds in wood preservation. Due to the voluminous literature, ie some 270 papers which are cited in the references, only an introduction into the problems and main results but not a detailed review of the publications is possible. The subjects dealt with in the publications are indicated in the references. With some exceptions the brief survey is limited to the compounds and mixtures without chromium which remain leachable in the wood. Questions of toxicity to human beings, animals and plants are not discussed in this paper.
G Becker


Maintaining the adoption of the equilibrium moisture content in timber by bifluorides under outdoor circumstance
1989 - IRG/WP 3541
A description is given of the practical application of bifluorides, f. ex. Diffusec in maintaining the adaption of the equilibrium moisture content in timber, as a result of a many years observation of treated timber under outdoor circumstances.
H F M Nijman


Treatment of dried sawn spruce and redwood building timbers with water-borne preservatives under a scheme for the quality control of the preservation and preserved wood in the Netherlands
1978 - IRG/WP 3123
Treatment of dried sawn spruce and redwood Building Timbers with water-borne preservatives under a scheme for the quality control of the preservation and preserved wood in the Netherlands. The aim of this article is to give the reader a modest description of the evaluation of fundamental research in wood preservation into a practical application.
H F M Nijman, N Burgers


The utilization of preserved rubberwood
1982 - IRG/WP 3186
The paper examines the use of processed and kiln-seasoned rubberwood for manufacturing furniture and doors and windows, discusses methods tested and found acceptable for preserving the timber as well as for drying the treated timber in conventional kilns. It considers a type of furniture where narrow width timber of preserved and kilned rubberwood has been used with great success. It recommends that wherever rubberwood is available, its use could be very profitable to local entrepeneurs.
V R Sonti, B Chatterjee, M S Ashraf


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