Your search resulted in 118 documents. Displaying 25 entries per page.
The Development of a novel method to preserve reeds using an environmentally friendly timber preservative and a unique engineering design.
2006 - IRG/WP 06-40335
Reeds are used in the construction of bush lodges in Northern Kwa- Zulu Natal, South Africa. Fungal, insect and ultra-violet damage to these reeds is posing a severe problem. Within a space of two years, the reeds are attacked and have to be subsequently replaced; a time consuming and costly exercise. A novel method has been used to successfully preserve these reeds with an environmentally friendly preservative containing disodium octaborate tetrahydrate in a water-based polymer system. The polymer allows for uninhibited diffusion of boron into the reeds, whilst the polymer cures to form a continuous protective film. By making use of two strategically drilled holes, which are 2 mm in diameter, the preservative is introduced into the reed shafts and nodes. The boron successfully diffuses into the walls of the reeds and is prevented from leaching out of the reeds. The water-based polymer provides sufficient protection against excessive ultra-violet damage. The test site, which is situated in the Hluhluwe Game Reserve in Northern Kwa-Zulu Natal – South Africa, has been monitored for nearly two years and there are no sign of insect or fungal damage to the reeds. Over the two-year period, the reeds were periodically inspected for deterioration in colour and deterioration in structural integrity.
K Govender, K G Moodley
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.
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
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.
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
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
Diffusion treatment plants (Latin America - Africa)
1974 - IRG/WP 333
B N Prasad
HCB - a new preservative combination for wood pole maintenance
1996 - IRG/WP 96-30122
New combination of heavy creosoted boron (HCB) applied on hardwood and softwood logs at different moisture content revealed successful diffusion of boron in all sapwoods within 7 days and in all sapwoods plus hardwoods within 15 days. The new cost effective paste sterilizes wood through diffusion and suitable for pole maintenance at groundline and above groundline e.g. cut ends, drilled holes, woodpecker's holes etc.
A K Lahiry
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
Time dependent over-uptake of etherificated melamine resins
1998 - IRG/WP 98-40109
Waterbased methanol-etherificated melamine-formaldehyde resins can increase the fungal resistance of the treated wood though they are known to be non-toxic. Therefore melamine-resins are at the present an object of research activities of European projects and of some companies. The paper highlights the importance of quoting the duration of the diffusion when immersed in the treating solution, as major differences in the effectiveness against fungal attack can be obtained by extending the diffusion period. This paper also critically reviews the practice of referring the concentration of the solutions used for impregnation to a fixed solids content of this type of resins.
D Lukowsky, R-D Peek
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
The internal-external diffusion process: Table salt treated poles
2005 - IRG/WP 05-50224-25
This new technique of preservation of wooden poles consists of keeping preservative in stock, in a reservoir drilled inside the pole, in its whole length. This permits the use of non toxic, common products such as table salt, grease, etc, in the preservation of utility poles, building columns, or the like. Some major obstacles to a good implementation of a good preservation with the classical processes become advantages with the new technique, notably the low permeability of some sorts of wood, and inaptitude to the fixing of a big number of chemicals aimed to provide a durable protection to wood submitted to weather.
Diffusion of bifluorides and borates from preservative rods in laminated beams
1991 - IRG/WP 3644
Laminated beams from spruce, pine and larch were treated with two preservative rods, based on bifluorides and octaborate respectively. After 3 and 6 months placed in different climates (65% r.h., 100% r.h., water) the diffusion of the active ingredient was measured. After the 6 months period, the diffusion of the bifluorides was, in all species, ca. 5 times larger than the diffusion from octaborate rods. The bifluorides were not hindered by the glue-lines. The diffusion of the borate was poor, mainly perpendicular to the grain and was hindered by the glue-line.
A method for determining boron diffusion coefficients in wood
1999 - IRG/WP 99-30200
The radial unsteady-state diffusion coefficient for boron in southern yellow pine (Pinus spp.) was determined from measured concentration profiles using Egner's solution, a modified form of Fick's second law. The method uses a slicing technique to accurately determine concentration gradients with time in a single direction. The methodology should be applicable to any diffusible system.
J-B Ra, H M Barnes
Preliminary note on the fungal problem of rubber wood
1983 - IRG/WP 3246
Susceptibility of rubber wood to fungal attack limits its wider utilisation. Fungal problems encountered in treating rubber wood with boron compounds by diffusion process have been discussed. Sodium pentachlorophenoxide and 2-thiocyanomethylthio benzothioazole (TCMTB) were investigated for possible control of fungal growth during diffusion storage and their performance has been reported.