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Testing wood in ground contact: An artificial soil
1977 - IRG/WP 280
This document is an interim report on the development of the artificial soil medium. It includes some information on the relationship between soil, wood and water which is of relevance in testing.
E F Baines, D J Dickinson, J F Levy


Modélisation sur maquette du rejet accidentel d'un gaz toxique et inflammable dans l'atmosphere - Emission de type "bouffée d'oxyde d'éthyléne [Water model simulation of toxic and flammable gases in the environment on industrial sites - Puff of ethylen oxide]
1990 - IRG/WP 3576
M Milhe


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


Decay patterns observed in butylene oxide modified ponderosa pine attacked by Fomitopsis pinicola
1983 - IRG/WP 1183
Small blocks of ponderosa pine chemically modified by butylene oxide to three different weight percent gains (WPG) were decayed for 2 months with the brown rot fungus Fomitopsis pinicola. Wood substance loss and the type of decay pattern recognised were fairly similar both for control and blocks treated to 8 and 15 WPG. No difference in attack was observed between radial or tangential walls in latewood tracheids. Microscopical examination of undecayed wood blocks treated to 23.7 WPG revealed numerous cracks in both the middle lamella regions of radial walls and in cell corners of latewood tracheids. The fungus had gained entry to the cracks, possibly via bordered pits and rays. Attack started from the cracks and progressed along the middle lamella and towards the cell lumen.
T Nilsson, R M Rowell


Effect of fatty acid removal on treatability of Douglas-fir
1993 - IRG/WP 93-40008
Treatment of Douglas-fir with chromated-copper-arsenate (CCA) poses a major challenge. Several hypotheses based on the anatomical aspects as well as chemical reactivity of the preservative formulations with cell wall constituents and deposits have been proposed. Techniques to prevent pit aspiration or slow fixation reactions have, however, not significantly improved treatment. The presence of high molecular weight fatty acids have been reported to be responsible for higher hydrophobicity in some wood species. These acids can react with Cu+2/Cr+3 ions to form insoluble metallic soaps, thereby immobilizing Cu/Cr and increasing wood hydrophobicity by a mechanism similar to that employed in paper sizing. The effect of fatty acids on treatability was explored by removing these components via several extraction methods. In general, extracted wood had higher gross solution absorptions and chemical retentions, but preservative penetration was largely unaffected. The results suggest that removal or disruption of fatty acids can improve treatability of Douglas-fir heartwood.
S Kumar, J J Morrell


Detoxification of preservatives: Tri-n-butyltin oxide as a biocide
1982 - IRG/WP 1156
T E Dudley-Brendell, D J Dickinson


Rapid leaching test
1991 - IRG/WP 2367
An accelerated test which is suitable for measuring the extent of metal fixation in both chromium and non chromium containing preservatives is described.
J A Cornfield, M Bacon, A Lyman, C Waldie, M R Gayles


Fixation of CCA in Pinus sylvestris after kiln-drying
1990 - IRG/WP 3594
Tanalith C Paste is 98% fixed and Tanalith Oxide C is 99% fixed irrespective of whether treated Pinus sylvestris is kiln or air dried. A schedule suitable for kiln drying of CCA treated Pinus sylvestris is described.
P Warburton, J A Cornfield, D A Lewis, D G Anderson


Effect of sterilization method on germination of spores of wood decay fungi observed by contact agar block method
1978 - IRG/WP 2117
Previous studies of germination of spores of wood decay fungi on wood have generally concluded that method of wood sterilization has little significant effect on germination response. This study expands the numbers of test fungi as well as number of sterilization methods employed to determine the influence of sterilization method on spore germination response of decay fungi. Germination was assessed on agar discs fused by aqueous diffusion path to 1 cm³ samples of aspen and white spruce sapwood.
E L Schmidt, D W French


The formation of organotin carboxylates in bis(tributyltin) oxide - treated Pinus sylvestris sapwood
1990 - IRG/WP 3618
Tributyltin compounds have been successfully used for many years as wood preservatives, although their chemical nature in timber have not been fully elucidated. This study by 119Sn and 13C NMR spectroscopy has shown that, on impregnation into Pinus sylvestris sapwood, bis(tributyltin) oxide, (Bu3Sn)2O, is rapidly converted to tributyltin carboxylates, Bu3SnOCO·R, via reaction with components of the wood resin. It is further suggested that the formation of these species is a prerequisite for the known disproportionation reaction which occurs in (Bu3Sn)2O - treated timber.
S J Blunden, R Hill


Decay patterns observed in butylene oxide modified ponderosa pine after exposure in unsterile soil
1982 - IRG/WP 3211
Small blocks of ponderosa pine (Pinus ponderosa Laws) chemically modified with butylene oxide to three different weight gains were exposed for 6 weeks in unsterile soil. Severe surface decay caused by soft rot fungi and tunnelling bacteria was observed in blocks with 8 weight percent gain. The soft rot attack was restricted to the outer parts of the radial walls in the latewood tracheids. Bacterial attack occurred both in the radial and tangential walls. Very few soft rot cavities were found in blocks with 15 weight percent gain. Some attack by tunnelling bacteria was observed in the outermost parts of the radial walls in the latewood tracheids. Wood blocks with 23.7 weight percent gain showed no signs of attack. A solution of crystal violet was used for examining pathways in ponderosa pine wood. The results indicate that the uneven distribution of cavities is due to improper penetration of the modifying agents into the outer parts of the radial walls in the latewood tracheids.
T Nilsson, R M Rowell


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


Comparisons of differences in electrical conductivity and corrosivity between CCA-oxide and CCA-salt treated wood
1981 - IRG/WP 3178
CCA preservatives have served well in many applications throughout the world. In developed areas it is the preservative in demand for clean dry paintable surfaces with long durability. In developing areas it is widely used for economic and logistical reasons. With the current emphasis on energy resources, the CCA preservatives are gaining greater acceptance as a substitute for hydrocarbon-related preservatives. While there are several formulations with apparent wide differences in the proportions of active ingredients, (chrome, copper and arsenate), the performance of each appear to be essentially equivalent as wood preservatives. This performance has lead to an almost blind acceptance in the market place in the U.S. in that any CCA is considered equivalent in all respects. When all aspects are considered, it is readily apparent that this equivalency does not exist.
J A Taylor


The chemical nature of bis(tributyltin) oxide in Pinus sylvestris sapwood
1989 - IRG/WP 3508
Tributyltin compounds have been used for many years as wood preservatives. This study has provided, for the first time, an explanation for the previously reported dealkylation and/or volatilisation of the tributyltin species in, and from, Scots pine (Pinus sylvestris) sapwood. Thus, 119 Sn nuclear magnetic resonance studies have shown that, on impregnation into this timber, bis(tributyltin) oxide is rapidly converted to other tributyltin species, Bu3SnOX, and that these subsequently undergo disproportionation to Bu4Sn and Bu2Sn(OX)2 compounds. We have additionally demonstrated that Bu4Sn, so produced, is not substantive in Pinus sylvestris and is lost by volatilisation. Since the rate of disproportionation of the Bu3SnOX species should be dependent upon the nature of the X group, it should be possible to significantly affect, if not stop, this process by the use of alternative tributyltin fungicides, e.g. tris(tributyltin) phosphate or tributyltin methanesulphonate. However, tributyltin fungicides have been used successfully in wood preservation for at least 25 years. Therefore, it must be concluded that, even after disproportionation in timber, in service, sufficient preservative action is retained to prevent decay of wood under the conditions of natural exposure. Nevertheless, it is becoming evident from this work and from previous studies of the compatibility of tributyltin fungicides with synthetic pyrethroid insecticides, that, on chemical grounds, (Bu3Sn)2O should not be the preferred tributyltin preservative.
S J Blunden, R Hill


Leaching of Arsenic from Mulch Made from Recycled Construction and Demolition Wood
2005 - IRG/WP 05-50232
Mulch made from recycled construction and demolition (C&D) wood has been reported to contain chromated copper arsenate (CCA)-treated wood and potentially release arsenic in the leachate by rainfall. Such recycled wood mulch is commonly masked with iron-oxide colorant, which is known to combine with arsenic. The objective of this study was to evaluate the levels of arsenic leaching from C&D recycled wood mulch and potential effects of the colorant on leaching rates. Mulch samples observed were paired (dyed and non-dyed) in three groups [untreated wood, 5 % treated wood, and 100 % treated wood]. The leachates were collected for one year and analyzed for arsenic. Arsenic in the leachate from untreated wood mulch was consistently at low levels (< 3 ~ 13 ug/L). The average concentrations from 5 % treated wood mulch were 341 (non-colored) and 258 &#956;g/L (colored). The average concentrations from 100 % treated wood mulch were 4,490 (non-colored) and 3490 &#956;g/L (colored). For the entire one year monitoring period, the colorant reduced the arsenic concentration by 24 and 29 % for the non-colored 5 % treated wood mulch and 100 % treated wood mulch, respectively. The study showed that recycled C&D wood mulch, which contains small percentages of CCA-treated wood, release significantly large levels of arsenic by rainfall and iron oxide colorant reduces the arsenic leaching rate for a short period.
T Shibata, H M Solo-Gabriele, T G Townsend, B Dubey


Low polymer levels containing bioactive monomer polymerized in situ provide resistance to Gloeophyllum trabeum
1995 - IRG/WP 95-30066
Wood preservation based on in situ polymerization of potentially bioactive monomers has been studied. Tributyltin oxide acrylate (TBTOA) and pentachlorophenol acrylate (PCPA) were synthesized. Wood samples were treated at 2, 5, 10, 15 and 20% by weight solutions with varying amounts of crosslinker (trimethylolpropane trimethacrylate, TMPTM) and polymerized in situ in wood samples (2.54 x 2.54 x 0.635 cm³). Methyl methacrylate (MMA) also was run at the same concentrations as a non-bioactive monomer comparison. Soil block testing was performed on acetone leached samples using Gloeophyllum trabeum in a standard ASTM test for 12 weeks. TBTOA was effective at all levels except when using greater than or equal to 10% crosslinker concentrations. PCPA showed some efficacy with 0% crosslinker present, but otherwise it gave no more protection than the MMA controls alone. This is probably due to the stable ester linkage formed in the polymer. Further investigation is underway to synthesize and biologically evaluate new bioactive monomers at low polymer levels for wood protection.
R E Ibach, R M Rowell


Influence of CCA and TnBTO on wood decay, under different oxygen levels and various initial moisture content
2001 - IRG/WP 01-10415
Fagus sylvatica (beech) and Pinus sylvestris (Scots pine) were impregnated by TnBTO (tributyl-tin oxide) and CCA (chromated copper arsenate). In wood blocks two levels of moisture content (50% and 100% of saturation point) were used. Three levels of oxygen concentrations (10, 21, and 50%) were chosen. Treated and untreated wood were exposed to three fungi (C. versicolor a white rot, C. puteana, a brown rot, and C. globosum a soft rot). The results showed when TnBTO was used and wood samples exposed to C. versicolor between treated (TnBTO) and untreated specimens was no a big difference in weight losses. Using high moisture content (100%) in wood blocks caused very low weight losses in all treatments to be appeared. When CCA was applied decay by C. puteana was very decreased in Scots pine, therefore, there was a large difference in weight losses between treated and untreated wood. Low oxygen and high moisture content in treated samples caused wood decay by C. puteana did not occur. In the case of C. globosum effect, increasing the moisture content caused that wood decay in all specimens (treated and untreated) to be increased. However, low oxygen concentration in middle moisture content (50% SP) increased decay in beech.
S M Kazemi, R J Murphy, D J Dickinson


The Protection of Wood with Oxy-aluminium Compounds
2002 - IRG/WP 02-30286
Wood inorganic composites (WICs) containing aluminium compounds were developed and tested in relation to some essential requirements of preservative treated wood. Four different oxy-aluminium treatments were developed and identified according to the final insoluble compounds formed (sodium aluminate, aluminium hydroxide, magnesium aluminate and aluminium borate) in wood. Vacuum impregnation or double diffusion were used as delivery systems for the chemicals. Higher weight percent gains were obtained when wood was treated by vacuum impregnation. Inorganic deposits were detected throughout the structure of treated wood using scanning electron microscopy. A high degree of dimensional stability was imparted to Scots pine by the treatments, and significant dimensional stability was retained even after treated wood was subjected to cold-water leaching. The oxy-aluminium treatments did not, however, impart water-repellency to wood. The decay resistance of oxy-aluminium treated wood, which was assessed through the use of terrestrial microcosms, was dependent on treatment, soil type and temperature, and exposure times. Oxy-aluminium treated wood showed increased resistance to brown rot. Sodium aluminate and aluminium hydroxide were more effective than magnesium aluminate and aluminium borate in protecting wood against soft rot. The results suggest that it is possible to protect some important wood properties with the use of oxy-aluminium compounds. Further research is needed to fully explore the potential of oxy-aluminium treatments for the protection of wood.
F A Ximenes, P D Evans


The effect of preservative distribution in small blocks of Pinus sylvestris on the toxicity of tributyltin oxide to Reticulitermes santonensis Feytaud
1971 - IRG/WP 206
Small blocks of Pinus sylvestris (50x25x15 mm³) were treated by a full-cell method with various concentrations of tributyltin oxide in benzene. Replicate blocks were then freeze dried, rapidly air dried or slowly air dried and exposed to surface attack by the subterranean moistwood termite Reticulitermes santonensis Feytaud. At all concentrations it was found that the freeze-dried blocks were more heavily attacked than the air-dried ones, and that a threshold value determined in the normal way using air-dried blocks could be much underestimated. This agrees with what one would expect from the uneven distribution of preservative produced by air drying compared with the uniform distribution obtained by freeze drying. The results with slow air drying were in between those obtained from the other two methods. Further work is required to check the value of this method.
M P Levi, D N R Smith


Pentachlorophenol and tributyltin oxide - the performance of treated Pinus radiata after 12 years' exposure
1986 - IRG/WP 3361
Pinus radiata samples were impregnated with a range of light organic solvent preservatives and copper/chrome/arsenic salt and exposed with no surface coating both in and above ground for 12 years. Inspection of the test samples revealed that some formulations of light organic solvent preservatives will give good fungal protection and reduce splitting in Pinus radiata exposed externally without a supplementary surface coating. Tributyltin oxide performed poorly in the test compared to pentachlorophenol which gave relatively good protection under both hazard conditions. Copper/chrome/arsenic salt was clearly the most effective.
R S Johnstone


Experiments on the degradation of tributyltin oxide: A progress report
1984 - IRG/WP 3287
A variety of experiments designed to assess the chemical and physical factors affecting the degradation of tributyltin oxide in treated timber are described. Simple procedures in which temperature and oxygen availability were increased in the presence of wood and water suggest that the wood itself was of prime importance. Attempts to decrease degradation with antioxidants were unsuccessful but led to the idea that free radicals may be instrumental in the degradative mechanism. Subsequent work in which a range of antioxidants and free radical producing systems were used confirmed the susceptibility of tributyltin oxide to the action of free radicals. It is suggested that the presence of free radicals in the painted and treated wood system may be an important factor in the eventual degradation of tributyltin oxide.
R J Orsler, G E Holland


Environmental consequences of various materials in utility poles - A life cycle analysis
1992 - IRG/WP 92-3726
A model for environmental life cycle analysis, LCA, has been created to compare environmental impact from transmission poles, made alternatively of concrete, steel, aluminium and pine wood treated with CCA type B or creosote. The main pollution sources and energy use are included in the LCA. One pole size, 12 meters long, is presented in the study, a so called "45 kV" pole. Poles of different materials can be divided into different groups considering different types of pollution. The use of poles made of concrete, steel and aluminium leads mainly to emission to the air, while treated wood mainly leaches preservatives during the operation and service phase. It is, by the knowledge we have today hard to compare these two types of discharge.
M Erlandsson, K Ödeen, M-L Edlund


Tropical In-Ground Durability of Structural Sarawak Hardwoods Impregnated to High Retention with CCA-salts, CCA-oxide and FCAP after 20 Years Exposure
2005 - IRG/WP 05-30384
Statistical analysis (ANOVA) was conducted on durability (termite and decay combined) rating data collected over 20 years exposure period of over 140 species of Sarawak timbers with altogether 30,000 stake specimens, at the Forest Department’s Sibu “graveyard” stake test sites from 1977. About 20 replicated stakes were pressure-treated to refusal with 10% g/ml concentration of up to 3 CCA-salt formulations and 1 CCA-oxide product and FCAP were visually evaluated every 6 months according to the 5-point ASTM D1758 durability rating scale, and the treated durability results reported in this paper are between 5 and 20 years exposure. The analysis was confined to 7 relatively high density hardwood species that are regarded suitable for in-ground structural use (ie, basic density >600 kg/m3), and had achieved a minimum preservative retention of 16 kg/m3 (as required for CCA-salts) but up to 48 kg/m3 retention. The results revealed that the in-ground durability of treated wood decreased usually after 5 years to poor-to-moderately durable levels with CCA-salts, moderate-to-high durability with CCA-oxide, but failed with FCAP after 20 years. CCA-oxide treated hardwoods out-perform the CCA-salt treated counterparts despite their relatively similar retention and “over-treatment factor”. The non-leach-resistant FCAP is clearly unsuitable as an industrial used in-ground wood protectant.
Wang Choon Ling, A H H Wong


CCA type C depletion of Southern yellow pine utility poles
1995 - IRG/WP 95-50049
Depletion and redistribution of preservative components were evaluated on five CCA-C treated poles in service for over six years in Conley, Georgia. A statistical approach was taken in which retentions below ground were compared to retentions above ground due to a lack of initial data on individual poles. It was hypothesized that the below ground retentions should be lower than the corresponding above ground retentions based on the premiss that wood in ground contact is subject to a higher leach potential than wood above ground contact. There were no significant differences between above ground and below ground CCA-C retentions in any of the six 12.5 mm zones. Linear regression performed on the retentions across zones showed no significant difference between the slopes of the gradient curves on either exposure for any of the components indicating there has been no redistribution of chemicals among zones.
P D Osborne, R F Fox


Evaluation of hydroxamates as wood preservatives
2004 - IRG/WP 04-30330
Fungicidal activity of different hydroxamates was investigated by laboratory malt-agar block tests to evaluate their potential as wood preservatives. Results obtained indicate that benzohydroxamic acids substituted or not on the aromatic nuclei were unable to protect wood blocks against the white rot fungus Coriolus versicolor while 2-hydroxypyridine-N-oxide (2-HPNO) possesses an interesting activity. The effect of 2-HPNO was also studied on Poria placenta, a brown rot fungus, and the minimal inhibiting concentrations determined on both rotting fungi. Structure/activity relationships evaluated with different analogs of 2-HPNO as hydroxypyridine (2-HP), 3-hydroxypyridine-N-oxide (3-HPNO) and pyridine N-oxide (PNO) indicated that hydroxamic acid is essential for antifungal activity.
P Gérardin, S Dumarçay, E Gelhaye, A Mbamba, V Mussavu


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