Your search resulted in 97 documents. Displaying 25 entries per page.
Termite Management and the U.S. Experience: A Case for Wood Treatment & Integrated Control
2015 - IRG/WP 15-30678
A brief overview of termite control is given using specific experiences from the U.S.A. Five major types of termite treatment now prevail: soil applied chemical barriers, in-structure chemical barriers (in-situ applied wood and foundation treatments), physical barriers, treated wood and termite baits. In general, ‘stand-alone’ pretreatments or ‘primary’ treatments are often discussed and even required, although in actuality control typically relies on a number of interacting factors. The different termite control systems are discussed as well as some important building code and construction aspects which can help or hinder long-term protection against termites. The control strategies in current use are explained and performance of primary control strategies for various pests and construction types, and possible supplemental treatments are suggested. It was found that no single treatment can perform in all areas and on all construction types and a summary table developed should help specifiers select appropriate protection.
J D Lloyd, K van den Meiracker
Low temperature drying conditions of Pinus radiata wood for avoiding internal stain
1989 - IRG/WP 3507
It has been observed that, if in little sawmills, timber is dried with a low temperature schedule, it arrives at destination with internal sapstain besides of superficial mould. In this study, the lowest drying temperature at which wood should be exposed for sterilization, which results to be 52°C, is searched. It is not possible to avoid entrainment of pentachlorophenol, even though a waiting period of 72 hours after dipping the wood in a pentachlorophenate/borax solution before drying is considered. The residual content of pentachlorophenol in wood should be at least 400 µg/cm² or the moisture content less than 23% for avoiding the development of mould.
M C Rose
Effect of protective additives on leachability and efficacy of borate treated wood
2002 - IRG/WP 02-30290
Borate preservatives have been used extensively in many countries as an effective means for protecting wood against fungal and insect attack especially in interior environments. Under exterior conditions, borate compounds have a main disadvantage as they can be leached from treated wood as a result of their water solubility. In this study, we compared the potential of different additives for reducing the leachability of boron preservatives from treated wood. Scots pine sapwood (Pinus sylvestris) and poplar (Populus trichocarpa x deltoides) test samples were vacuum treated with 1 % BAE (Boric Acid Equivalent) disodium octaborate tetrahydrate (DOT) solutions containing various additives e.g. glycerol/glyoxal, polyvinylpyrrolidone (PVPY), a commercial resin compound and a commercial water repellent. The European Standard EN 84 was used as a leaching test for both coated and uncoated specimens. The results of chemical analysis of leachates taken at different periods showed that the use of protective additives reduces the boron leachability. The glycerol/glyoxal additive applied to treated pine sapwood showed the best performance. The percent of boron retained in uncoated pine sapwood was 26% while coated samples still retained 45% after 14 days of intense leaching. Similar tests on poplar revealed 19% and 34% for uncoated and coated samples, respectively.This represents a gain of 20 to 25% compared to pure DOT treated specimens of both wood species. Preliminary biological tests were carried out on malt agar using a miniblock technique for uncoated pine sapwood and beech, with Poria placenta and Coriolus versicolor, respectively. After six weeks of exposure to fungal attack all boron protective systems tested proved their effectiveness, as none of the test samples exhibited a mass loss exceeding 4%. The reference 1% BAE without protective additives showed an average mass loss of 15%. Finally, test data are reported of standard EN 113 testing in view of a further evaluation of the biological efficacy of combined DOT-additive treatments.
A Mohareb, J Van Acker, M Stevens
An attempt to evaluate wood resistance against fungal decay in non-sterile conditions by measuring the variation of resistance to bending test
1988 - IRG/WP 2308
The main object of this work was to determine the variation of strength on large test specimens of wood (800 x 45 x 45 mm³) when exposed to accelerated fungal attacks close to natural conditions, out of test vessels. The modulus of elasticity (MOE) and the modulus of rupture (MOR) have been assessed. Thereby, the natural resistance of the wood species to fungal decay, the efficiency of preservative as well as the treatment applied are discussed. The wood tested is a guianese secondary species (Couma guianensis). The fungi tested are two guianese strains of brown and white rot. The exposure time is 12 weeks. No mould contamination has been recorded by use of a selective fungicide. The results obtained show that it is possible to infest in nonsterile conditions large wood specimens. Furthermore, modulus of rupture appears to be the most reliable criterion. The investigation, that requires limited equipment and staff could be performed in any tropical research station as it has been done at CTFT, French Guiana center.
L N Trong
Rules and conditions of the Ron Cockcroft Award Scheme RCA
1994 - IRG/WP 94-60025
Conditions of the Ron Cockcroft Award scheme
1997 - IRG/WP 97-60086
Conditions of the Ron Cockcroft Award scheme (RCA)
2003 - IRG/WP 03-60177
Conditions for membership of IRG
1994 - IRG/WP 94-60024
Conditions for membership of IRG
2003 - IRG/WP 03-60176
Conditions for membership of IRG
2007 - IRG/WP 07-60246
Conditions and possibility of nanobiocides formulation for wood protection
2008 - IRG/WP 08-30467
During development of nanobiocides for wood protection the need to identify mineral composition of wood in respect of trace elements and nourishing conditions of wood destroying fungi in relation to these elements was discussed.
J Wazny, A Kundzewicz
Conditions for membership of IRGWP
2012 - IRG/WP 12-60338
Conditions for membership of IRGWP
2017 - IRG/WP 17-60411
Observations on the failure of anti-sapstain treated timber under non-drying conditions
1990 - IRG/WP 1437
A range of bacteria and yeasts were isolated from antisapstain treated timber and fresh sawdust. Solution samples containing 100 ppm of TCMTB in a nutrient medium were inoculated with these organisms and incubated at 25°C for 5 days. The levels of TCMTB remaining in solution were determined by HPLC analysis after this time. Results indicated high losses of active ingredient for a range of organisms. These results suggest that active biodetoxification of organic biocides could occur in a short period of time during storage of antisapstain treated timber under favourable conditions. The implications of these results are discussed.
G R Williams
Accelerated wood decay in a soil bed test under greenhouse conditions compared with a stake test under field condition
1991 - IRG/WP 2384
The rate of decay of oak, beech, Douglas fir, pine and spruce stakes in an outside test field were compared with the decay rate of the same species in a greenhouse soil-bed test. Strength loss after four and six months respectively was measured by determining the compression strength parallel to the grain. The results show that all species, strength loss in the greenhouse was 2 to 4 times higher than under field conditions. The rate of strength loss correlates with the rate of weight loss.
J E Polman, S G Michon, H Militz
Effects of timber surface properties and dipping conditions on uptake of antisapstain actives from two aqueous suspensions, and ultimate effects on efficacy against mould and staining organisms
1995 - IRG/WP 95-30073
Green-off-saw rough sawn Pinus elliottii (slash pine) boards were dipped in aqueous suspensions of two antisapstain formulations, and the resultant surface retentions of active ingredients MTC (methylene bisthiocyanate), CTL (chlorothalonil) or TCMTB (2(thiocyanomethylthio)benzothiazole) were monitored by chemical analysis. Surface retentions increased with suspension concentration and surface roughness, and decreased with initial timber moisture content. Dipping time beyond 20 seconds, timber basic density and earlywood content had little effect. Relatively low surface retentions, produced by dipping smoother boards with higher initial moisture contents, provided lower protection against mould and stain during seasoning than higher retentions. Equations describing the effect of surface retention on efficacy were developed for both formulations, and retentions providing complete protection under the conditions of the test were determined.
M J Kennedy, T L Woods
Conditions for basidiospore production in the brown rot fungus Gloeophyllum separium in axenic culture
1984 - IRG/WP 1232
Attempts to control and optimize the production of hymenial structures and basidiospore production in Gloeophyllum sepiarium in axenic culture resulted in the proposal of the following conditions as being suitable. The dikaryotic mycelia originally isolated from basidiocarps could consistently be induced to produce hymenial structures and pure basidiospore collects if illuminated by near ultraviolet light with emission maximum at 355 nm ("black light") at a temperature of 15°C on a chemically defined medium, where the concentration of the carbon and the nitrogen sources were shown to be of critical significance. The necessary conditions for basidiospore production in lignicolous fungi in general are is briefly discussed.
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
Effect of asphyxiation on wood decay fungi treated
with argon and nitrogen gas
2002 - IRG/WP 02-10452
The effects of low-oxygen conditions, achieved with either argon or nitrogen gas, on the viability of wood decay fungi Coniophora puteana, Antrodia vaillantii and Trametes versicolor, cultivated on PDA medium and infected wood samples, were examined. The fungal cultures were exposed to low oxygen concentration (below 10 ppm) for one to five weeks in hermetically sealed vessels. Anoxic treatment did not affect T. versicolor cultures in the time span of the experiment. Therefore treatment of only C. puteana and A. vaillantii mycelial cultures was extended to 10 and 16 weeks. After treatment, respiration and regeneration of mycelium were tested by measurements of CO2 production and resumed growth of hyphae onto fresh PDA growth medium. The effect of anoxic conditions on the mycelia of treated fungal species was expressed as an increased time needed for regeneration or as a complete absence of growth of inocula taken from the exposed cultures or wooden blocks reintroduced on new nutrient medium. The cultures that were retarded by the low oxygen concentration consequently produced less CO2. For C. puteana cultures, the effects of anoxic treatment became evident in the second week of the treatment. The number of affected cultures rose steadily with the prolongation of anoxic treatment. By the sixteenth week of the anoxic treatment, 80% of the inocula of C. puteana did not regenerate. A. vaillantii inocula regeneration was not affected until after the fourth week of treatment, and similarly for infected wood samples, after five weeks. The influence of anoxic treatment on the cultures of this species was more pronounced on the tenth and especially after the sixteenth week, when 67% of inocula did not regenerate. In general fungal species were differently sensitive to asphyxiation. T. versicolor cultures were not affected by anoxic conditions, caused by either argon or nitrogen gas, and A. vaillantii mycelial cultures proved to be less sensitive than those of C. puteana. In the test with infested wood blocks argon proved to be more effective, compared to nitrogen gas.
C Tavzes, F Pohleven, M Janisek, R J Koestler
Improvement of liquid penetration of wood by precompression under appropriate conditions and recovery process
1993 - IRG/WP 93-40014
A new system for enhancing the penetration of liquid into wood using a precompression treatment was designed, and the effects of compressive deformation and recovery on liquid uptake were evaluated. Precompression of up to 60% under appropriate moisture and heat conditions effectively increased the penetration of liquid into refractory wood samples of practical sizes without producing any strength reduction. Water-saturated wood was compressed perpendicularly to the grain at temperature of 30 to 80°C, and two types of pretreated wood were prepared; i.e., set-recovered wood in which loading was released immediately after precompression, and preset-fixed wood which was dried under the influence of a decompressive force. The amount of liquid taken up by set-recovered wood was 2-3 times that taken up by untreated wood. When preset-fixed wood was dipped in liquid and the deforming force was released, liquid penetration was more than 25 times that seen in untreated softwood heartwood. Liquid effectively penetrated even long samples when pressure impregnation was applied to precompressed and preset-fixed wood. No significant reduction of strength was observed for treated wood except for that which had been precompressed up to 60%. Fracture of pit membranes during compression with little damage to unpitted cell-walls and an elastic recovery process were believed to improve liquid penetration with negligible compression defects.
I Iida, Y Imamura
Effect of leaching temperature and water acidity on the loss of metal elements from CCA treated timber in aquatic conditions. Part 2: Semi-industrial investigation
1995 - IRG/WP 95-50040-13
In continuation of previous leaching research on the quantification and modelling of metal elements released from CCA treated timber, a series of experiments has been carried out dealing with the influence of temperature and pH of the relative aquatic environment. The leaching method used is the Dutch prestandard for building materials, a long term static leaching test simulating practical bank-shoring situations. Parameters of study are type of fixation, wood species and specimen profiles. With decreasing water temperature, significantly less leaching of copper, chromium and arsenic is observed. An outdoors/indoors temperature ratio of 0.7 could be established. Increasing acidity of the leaching water mainly enhances the release of copper, whereas chromium and arsenic show a minimum leaching tendency at neutral pH. Both conditioning chamber fixation and steam fixation prove to be effective in fixing the metal elements in the wood substrate. With steam fixed timber, however, a higher loss of copper is observed during the early leaching cycles, due to the presence of copper salts on the wood surface. With regard to specimen profiles, boards in comparison with posts demonstrate a remarkable resistance to leaching of active ingredients, presumably due to the different heartwood/sapwood distribution and the specimen dimensions. In conclusion, the observations made confirm the results obtained from previous leaching studies. Converting the emission data into leaching fluxes, a highly correlated double logarithmic flux formula is regarded the best tool for curve fitting, however, for a limited time span. Other models which are more suitable for extrapolation of emitted quantities over a longer period of time are still under investigation. Likewise, proprotional metal ratios versus retention levels highlight the relativity of experimental data obtained with standard emission tests.
G M F Van Eetvelde, W J Homan, H Militz, M Stevens
A new laboratory technique devised with the intention of determining whether, related to practical conditions, there should be a relationship between growth rate and decay capacity (of different strains) of Serpula lacrymans
1989 - IRG/WP 1384
Most laboratory techniques for the determination of growth rate not only use a medium (agar) unrelated to practice, but also yield values that are often far less than those found in practice. Also, most laboratory techniques for the determination of decay capacity ensure that the whole of a small test block becomes fully surface-colonised within the first few days; whereas in Australian practice Serpula lacrymans most often grows in one direction, from the walls across floorboards, with resulting collapse first evident near the ends of boards adjacent to that wall. This paper reports on a new, medium-scale, laboratory technique enabling growth rate measurements and (subsequently) a decay capacity measurement, all using the same piece of timber. Eight strains of Serpula lacrymans have been used in the three evaluation experiments carried out to date. Mean values for growth rate on wood have been suitably high, probably as high as for the most favourable practical situations. Resulting mass losses have, as was intended, been reduced in comparison with values previously obtained in small-scale techniques. This direct technique has confirmed the conclusions that others have made based on their comparisons; that it seems unlikely that the pattern of differences between growth rates of different strains has any consistent similarity with their corresponding decay capacities.
J D Thornton
The effect of selective additives and conditions on the decomposition of Basamid in Douglas fir heartwood
1992 - IRG/WP 92-3698
Basamid is a solid, powdered chemical used as an agricultural soil fumigant. Decomposition of Basamid isothiocyanate, hydrogen sulfide, methyl amine, and formaldehyde. Basamid has some potential as a wood fumigant, but it decomposes too slowly to be effective. Various additives and conditions were tested for their ability to enhance Basamid decomposition in Douglas-fir heartwood. Higher MC's and temperature, as well as copper sulfate and powdered pH 12 buffer increased decomposition rates with copper increasing the efficiency of breakdown to form MITC.
P G Forsyth, J J Morrell
Treating Eucalyptus tereticornis wood with boron: Optimizing treatment conditions
2005 - IRG/WP 05-40309
Even though Eucalyptus tereticornis wood is suitable for small timber purposes, being non-durable, it needs to be treated with preservative chemicals. As it is a heavy, hard and difficult to treat species, the possibility of using diffusible boron compounds was investigated. The present study explored the effect of impregnation conditions such as treatment schedule, concentration of treatment solution and the moisture content of wood on the achievement of desired dry salt retention (DSR) of the preservative in the treated wood by conducting a commercial scale trial. The study revealed that wood density and moisture content adversely affected the boron impregnation. It was clear that even E. tereticornis wood in green condition could be effectively boron impregnated using appropriate treatment schedule. Only long duration treatment schedules were found to yield the desired DSR levels. A solution concentration of 8% boric acid equivalent (BAE) was found to be required. Application of an initial vacuum of 760 mm Hg (- 85 kPa) for 15 minutes followed by a pressure of 1300 kPa for a minimum period of 60 minutes and a final vacuum of 760 mm Hg(- 85 kPa) for 5 minutes was found to be an appropriate treatment schedule.
T K Dhamodaran, R Gnanaharan
Leaching of CCA components from treated wood under acidic conditions
1993 - IRG/WP 93-50004
The leaching of CCA components from treated wood under acidic conditions were investigated. Western hemlock treated with three types of CCA and two levels of target retention was subjected to leaching at four different levels of pH. After leaching tests, leached samples were subjected to laboratory decay and soft rot tests. The amount of CCA components leached was dependent on acidity of leaching solution, CCA formulation, and target retention. The leaching of CCA components at pH 4.0 or above was not significant even though a relatively low amounts of arsenic were leached. The resistance of leaching according to the type of CCA was in the sequence of CCA-Type C (oxide), CCA-Type C (salt) and CCA-Type B (oxide). The amount of leaching was increased with the increase in target retention. The reduction of biological effectiveness was not distinct for treated wood leached in acidified water of pH 4.0 or above. Based on the results of this study, it might be concluded that losses of CCA components at pH 4.0 or above were not great enough to cause public concern about environmental problems and reduction of biological efficacy in service.
Jae-Jin Kim, Gyu-Hyeok Kim