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A comparison of inductively coupled plasma spectroscopy and neutron activity analysis for the determination of concentrations in wood
1993 - IRG/WP 93-10048
As wood decays the ionic composition changes, with increases often being seen in the concentrations of Ca, Mg, Fe, Mn and sometimes K. The concentration of eight cations in red spruce sapwood and heartwood samples was determined independently by inductively coupled plasma spectroscopy (ICP) and by neutron activation analysis (NAA) as part of an effort to standardize our analytical procedures and create a uniform wood standard for use by multiple researchers. Preliminary studies indicate a difference in the values of Ca and K as estimated by ICP and NAA, possibly due to a loss of these elements due to volatilization during ashing.
J Jellison, J Connolly, K C Smith, W T Shortle
Adsorption of ACQ components in wood
2010 - IRG/WP 10-30522
To investigate the chemical adsorption capacity of copper-monoethanolamine (Cu-Mea) components on wood, the Na+ cation exchange capacity (CEC) of red pine (Pinus resinosa Ait.) was determined and compared to the adsorption capacity of free Mea and Cu-Mea complexes. The CEC increased with increasing pH. Free Mea adsorption as a function of pH followed the sodium adsorption curve except at pH over 9, when it exceeded the CEC. Cu-Mea adsorbed up to the CEC at pH 9.0-9.5 apparently as Cu(Mea)+, whereas the complex in solution is predominantly of the form Cu(Mea)2+. For the quaternary ammonium compound, alkyl dimethyl benzyl ammonium chloride (ADBAC) adsorption isotherm showed two different adsorption mechanisms into wood: ion exchange reaction at low concentration and hydrophobic interaction at high concentration. ADBAC adsorbed at solution concentrations below a critical concentration (hemi-micelle concentration) had high leaching resistance while ADBAC adsorbed into wood at above the critical micelle concentration (CMC) had low leaching resistance. The CMC decreased with addition of Mea and Cu-Mea. The anion, Cl- of ADBAC was only adsorbed at solution concentrations above the CMC and was easily leached out. The adsorption capacity of ADBAC into wood by cation exchange reaction did not achieve the cation exchange capacity (CEC) of wood. However, the total adsorption of ADBAC and Cu achieve the CEC of wood in the presence of copper amine, and ADBAC competes with copper to occupy the same sites in wood.
Myung Jae Lee, P Cooper
A case study on quality control on telephone poles as a cost saving tool in Tanzania
1987 - IRG/WP 3418
A sample of 28 CCA treated Eucalyptus poles from a lot of 2,000 poles awaiting delivery to the field, was studied to reveal the quality of treatment. Results showed a product of very poor quality. Average figures for penetration and retention were 8.4 mm and 2.2 kg/m³; these results are 66% and 91% below the required standards, respectively. Consequences of such results are estimated to amount to losses of billion of shillings.
K K Murira
Wood extractive concentration and sem examination of pretreated southern yellow pine wood chips with blue-stain fungi for mushroom production
2001 - IRG/WP 01-10407
Mushroom-producing white-rotting basidiomycetes either do not colonize or else colonize very poorly on freshly prepared southern yellow pine wood chips. This study evaluates the resinous extractive content of southern yellow pine before and after treatment with colorless mutant blue-stain fungi. The blue-stain fungi penetrate into the sapwood of southern yellow pine and utilize nonstructural resinous extractives, simultaneously reducing the total resinous extractive content. Scanning electron microscopic examination showed that heavy mycelial growth with good sporulation occurred on the surface of wood chips within 2 days and in parenchyma cells within 6 days. Ophiostoma spp. removed 61.1% to 99.9% of the extractives from the southern yellow pine wood within a period of 4 to 5 days. We conclude that white-rot basidiomycetes can easily colonize and produce fruiting bodies on treated southern yellow pine wood wastes.
S C Croan, J Haight
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
The effect of temperature on the rate of fixation of an alkyl ammonium compound (AAC) wood preservative
1984 - IRG/WP 3293
The rate of fixation of an alkyl ammonium compound wood preservative was measured by soaking samples of wood wool in various preparations of the preservative for arbitrary times followed by immediate leaching in water. The wood wool was then analysed for residual preservative. The results indicated that fixation was very rapid and increased at higher temperatures.
CCA fixation experiments. Part 1
1989 - IRG/WP 3504
A method of squeezing solution from CCA treated wood that has not been dried at various times after treatment appears to be useful in following the fixation of CCA in wood. Experiments confirm that temperature governs the rate of fixation.
W S McNamara
Soil chemistry and wood decay
1978 - IRG/WP 2109
Soil is a most complex biological, chemical and physical material; its study is effectively a separate branch of science but almost entirely in relation to ist ability to grow plants - this paper is intendet just to note some known facets that might have relevance to the decay of wood and the performance of wood preservatives.
E A Hilditch
Investigation of the fixation in wood of chromated zinc chloride and copperised chromated zinc chloride preservatives
1976 - IRG/WP 372
A biological method of evaluating the extent to which CZC and CCZC preparations are retained in wood in terms of the potential protection which they afford against destruction by Merulius lacrymans (dry rot) is given. CCZC is recommended for protection of wood under moderate leaching conditions, while the use of CZC under such conditions is not recommended.
V N Sozonova, D A Belenkov
Health hazards and environmental aspects when using Cu-HDO-containing wood preservatives in vacuum pressure plants
1993 - IRG/WP 93-50001-11
Apart from the biological efficacy of wood preservatives, the health and environmental aspects concerning the utilisation of wood preservatives, the use of treated timber and the disposal of impregnated wood are of high significance today. Therefore, information on a possible aerial concentration of wood preservatives, on the mobility of active substances in soil leached from treated timber in service and on the composition and toxicity of thermal decomposition gases releasing on combustion of impregnated wood, are of absolutely fundamental interest. Measuring procedures relevant for the practical application will be presented, and the results concerning the utilisation of Cu-HDO-containing wood preservatives will be described. With the proper use of Cu-HDO-containing wood preservatives, the aerial concentration at workplace falls distinctly below the maximum permissible limit. If vacuum pressure treated timber is used properly, no active substances will seep into the ground water as a result of the leaching process of impregnated wood in service. The composition measured and the acute toxicity of the thermal decomposition gases released on combustion of impregnated wood may axtually be compared to those of untreated timber.
W Hettler, S Breyne, M Maier
Sludge formation in timber treatment with CCA preservatives. Origin and elimination
1984 - IRG/WP 3276
The exact distributions between lignin and holocellulose and retentions on wood of copper, chromium and arsenic as a function of various sets of conditions in a factorial experiment in which combinations of three temperatures of treatment, three CCA solution concentrations, four pH's of the initial CCA solution and two timber species, namely Pinus radiata and Eucalyptus grandis, are reported. Temperature and concentration appear to have an equally important effect on the preservative chemicals retentions and distribution in timber. pH, has also an effect but somewhat less marked than temperature and concentration, with the exception of the formation of sludges. Multivariable regression equations describing the amounts of Cu, Cr and As fixed on lignin and holocellulose for both pine and eucalyptus are also presented. The timber species treated also appears to have an important influence on the amounts of chemicals fixed and their distribution. Eucalyptus appears to be much less tolerant than pine to extremes of treating conditions. The influence of treating time under the most common treating conditions is also briefly discussed.
A Pizzi, W E Conradie, A Jansen
The influence of gaseous oxygen concentration on fungal growth rates, biomass production and wood decay
1998 - IRG/WP 98-10283
The effects of air and several levels of oxygen balanced with nitrogen (% oxygen (v/v) nitrogen to 100%) on growth rates, biomass production and wood decay were investigated. The best technique for measuring daily growth rates in anaerobic jars was found to be by using 40 mm petri dishes which were attached to the walls of the jars. At the end of the test period the same petri dishes were also used for determining the dry weight of the fungal mycelia. The results showed that 5% oxygen concentration was very favourable for white rot and brown rot fungi (Basidiomycetes). When oxygen levels were reduced from 1% to 0.01%, the growth rates and dry weight of these fungi were steadily decreased. On the other hand, there was a large difference between very low oxygen levels (0.01 to 1%) and other levels (5 to 21% 02). In the case of other fungi there was not a big difference on their growth rates and biomass. Observational and numerical results on Fagus sylvatica (beech) and Pinus sylvestris (Scots pine) degradation by Coriolus versicolor, Coniophora puteana and Chaetomium globosum showed that there was a large difference in the degradation of the wood samples caused by C. puteana and C. versicolor when exposed to air and other levels of oxygen (0.25,1, 5 and 10% 02). Weight losses obtained by C. globosum as a soft rot on timber specimens in air and other oxygen levels were all in same range and below 5%. On the other hand there was a safety point at 5% 02 below which the fungus was unable to degrade beech. This point was 10% 02 for scots pine. At these points, weight losses were under 5%.
S M Kazemi, D J Dickinson, R J Murphy
An investigation into the influence of soil cation exchange capacity on preservative component depletion
1994 - IRG/WP 94-20050
The mobility of preservative components from treated wood into the soil environment is regarded as an important determinant of preservative performance. Standard procedures for the investigation of this phenomenon have not been developed to any great extent. Soil bed studies conducted in this laboratory using natural soil and modified soil media have provided interesting comparative data on the influence of cation exchange capacity on preservative depletion. Some of these data are discussed with reference to the development of a standard soil contact depletion procedure.
K J Archer, L Jin
Practical consequences of the clarification of the chemical mechanism of CCA fixation to wood
1983 - IRG/WP 3220
Practical consequences derived from the chemical investigation of the mechanism of fixation of CCA to the wood constituents are discussed. Among these, formulas for the calculation of the time of hexavalent chrome fixation are presented. Furthermore, three parameters are shown to be important to the long-term effectiveness of CCA-treated timber: (i) the temperature of treatment, (ii) the initial pH of the CCA solution and (iii) its concentration. Variation in the values of these three parameters cause drastic differences in the distribution between lignin and holocellulose of the preservative chemicals which will considerably affect the durability of CCA-treated timber. New, more economical and more effective application schedules and CCA formulations both in chemical composition and requiring lower retentions (softwoods) and imparting equal or superior durability to the treated timber can be devised from the results presented. From the results it appears that CCA formulations producing better soft-rot resistant hardwoods can be devised and the changes necessary to obtain this, are outlined.
Environmental risk assessment of treated timber in service: The Environment Focus Group approach
2000 - IRG/WP 00-50162
In the context of the Biocidal Products Directive (98/8/EC), and of the OECD work on wood preservatives, the Environment Focus Group (EFG), comprising 8 institutes and the European Wood Preservative Manufacturers Group, has been working on the environmental risk assessment of treated timber in service. A literature review of emissions from treated timber has revealed that very little existing data is usable for environmental risk assessment; the most relevant data are kinetic curves of emissions over time, which show clearly the non-linear emissions behaviour of treated wood over time. The EFG has suggested real exposure conditions for treated timber in the environment, and listed typical exposure scenarios. Five representative scenarios are characterised in detail, for use in the calculation of Predicted Environmental Concentrations (PECs). The existing methods to determine emissions from treated wood have been reviewed. Most existing experimental models cannot be used to predict environmental emissions. Monitoring of commodities in service has its specific constraints. Chemical analysis and ecotoxicity testing have also been reviewed and their relationship has been discussed. Principles for the design of experimental models, for the determination of emission fluxes from treated wood to the environment, have been established.
G Deroubaix, G Labat, I Le Bayon, S Legay, P Marchal, C Yrieix, E Melcher, R-D Peek, S De Geyter, J Van Acker, W J Homan, D J Dickinson, R J Murphy, E D Suttie, A J Nurmi, A-C Ritschkoff, D Rudolph, I Stephan, D Aston, E F Baines, J B Simonin
Influence of concentration, catalyst, and temperature on dimensional stability of DMDHEU modified scots pine
1998 - IRG/WP 98-40119
Dimethyloldihydroxyethyleneurea (DMDHEU) is being used in textile industry to improve wrinkle recovery. Trials on solid wood have been performed to minimise swelling of the wood. This paper focuses on the effect of various types and concentrations of catalyst and reaction temperature on the dimensional stability of Scots pine. Three different catalysts, NKS (based on magnesium chloride), 3282 (based on aluminium chloride) and citric acid have been tried separately or in combination with tartaric acid. Reaction temperatures between 100° and 125°C have been investigated. The results showed that an anti shrink efficiency of up to 50% can be obtained.
M Van der Zee, E P J Beckers, H Militz
Occupant re-entry times following insecticidal remedial treatments of timber in dwellings
1995 - IRG/WP 95-50055
This work was carried out principally to obtain quantitative data on the aerial concentrations of permethrin and white spirit likely to arise following the remedial treatment of timber in buildings, using insecticidal formulations. Such data are needed to allow assessments to be made of the length of time buildings should remain unoccupied following such treatments prior to re-occupation, and the likely levels of exposure of the occupants to the treatment products concerned. Two large, free-standing, wood-lined chambers were treated (in separate experiments) with a dilute oil-in-water emulsion and a micro-emulsion, both containing 0.2% m/m permethrin. The atmospheres in the chambers were sampled at intervals and analysed for their permethrin content. In addition, the aerial concentrations of white spirit were determined following treatment with the dilute oil-in-water emulsion. Results indicated that the aerial concentrations of permethrin following treatment never exceeded 20 µg/m³. Comparison of the measured levels with the threshold limit value (TLV) for permethrin (modified to a TLV/40 to represent the value associated with 24 hours-a-day continuous occupancy) indicated that such levels of permethrin constituted no significant risk to occupants. Aerial concentrations of white spirit in the test chambers from the dilute oil-in-water emulsion product indicated by calculation that the TLV/40 of this solvent would be attained approximately 10 hours after treatment in a model domestic situation having the relatively low air exchange rates of the test chambers. This work has shown the importance of further studies needed to identify the rate determining step in the evaporation of deposited constituents from the surface of timber and to quantify the effect of different air exchange rates in treated premises on the aerial levels of formulation constituents.
R J Orsler, G E Holland, G M F Van Eetvelde
The suitability of high pressure sap-displacement for the retention of UK grown spruce and pine
1990 - IRG/WP 3595
The concentration and radial distribution of copper, chrome, arsenic (CCA), and the moisture content and depth of radial checking in UK grown, field exposed spruce and pine poles treated by high pressure sap-displacement are examined. The concentration of CCA elements in samples obtained from increment cores is similar in Norway spruce, Scots pine and Corsican pine but is significantly lower in Sitka spruce. The concentration of chromium in all species, arsenic in Sitka spruce, Norway spruce and Corsican pine and copper in Sitka spruce are at a maximum in the outer sapwood and decrease centripetally with increasing core depth. In contrast, arsenic in Scots pine and Norway spruce at groundline and copper in Norway spruce, Scots pine and Corsican pine are at a maximum in the inner sapwood. The slopes of metal concentration against radial core depth are similar in Norway spruce and Scots pine but are significantly larger (steeper) and smaller (less steep) respectively in Sitka spruce and Corsican pine. Checking is more severe in Sitka spruce than in the other species and appears to be associated with steep moisture gradients. In Sitka spruce, checks penetrate the preservative treated annulus thus greatly facilitating decay since micro-organisms have access to untreated non durable wood. The results suggest that high pressure sap-displacement is suitable for the treatment and long term protection of Norway spruce, Scots pine, and Corsican pine but is inadequate for the protection of Sitka spruce. Modifications to the high pressure sap-displacement process that could improve the treatment of Sitka spruce are discussed.
P D Evans, S D Hainey, A Bruce, G M Smith, B King
Evaluating the potential of amine chemicals for use as wood protecting agents. Part 1: Investigation of cation components of quaternary ammonium compounds
1994 - IRG/WP 94-30049
Quaternary ammonium compounds (quats) have shown a great potential as more environmentally acceptable wood preservatives. In order to identify chemicals possessing the wood protecting potential, an evaluation was carried out of a range of commercially available 'quats', using a modified soil block test. Ponderosa pine sapwood blocks were treated with selected 'quat', leached with water and sterilized with gamma radiation. The blocks then were exposed to Postia placenta, Gloeophyllum trabeum and Trametes versicolor in soil jars. After incubation at 25°C for twelve weeks, weight losses of the blocks after the test were calculated and the fungal toxic threshold determined. The four 'quats' examined were very effective in preventing attack of ponderosa pine sapwood blocks by the three fungi.
Hang Tang, J N R Ruddick
Effect of climate, species, preservative concentration and water repellent on leaching from CCA-treated lumber exposed above ground
2001 - IRG/WP 01-50178
Few studies have examined leaching of chromated copper arsenate (CCA) from treated wood in above ground exposures due to the assumption that leaching is less severe compared to wood in continuous contact with soil or water. However, a significant portion of CCA treated wood is used for above ground applications, exposing considerable volumes of the preservative to precipitation and potential leaching. This paper presents preliminary results of a one-year study that continuously monitors CCA leaching from above ground, naturally exposed 5.08 cm x 15.24 cm (2 x 6 inch) dimensional lumber. Three wood species, southern yellow pine (Pinus spp.), jack pine (Pinus banksiana Lamb.), and black spruce (Picea mariana (Mill.) B.S.P.), along with two preservative concentrations and one commercial water-repellent are evaluated for their effect on leaching rates. Preliminary leaching results indicate significant differences between wood species, treating solution concentrations, and the use of water repellent. In addition it appears that climatic variables affect elemental leaching of copper, chromium and arsenic differently. However, the exact effects of climatic variables are inconclusive at this time. Upon completion, this study will offer a substantial amount of leaching data to validate the findings of previous leaching tests, and provide insight into the leaching mechanism of CCA-treated lumber in above ground exposures.
J L Taylor, P A Cooper
The remaining concentration of inorganic wood preservative components in EN 252 stakes after ground contact
2000 - IRG/WP 00-50159
In order to determine the biological efficiency and the remaining concentration of different inorganic and organic active ingredients during service, EN 252 specimens were impregnated with 3 copper based wood preservatives. The stakes were installed in the test field of the DESOWAG GmbH, Rheinberg, for at least 7 years. At the end of the field test some of these stakes were divided into 10 uniform segments. Afterwards each segment was milled and mixed to guarantee a nearly homogenous sample. After further sample preparation like an acidic digestion the remaining concentration of the inorganic components copper, zinc, boron and fluoride were measured by means of AAS, ICP and an ion selective electrode. Concerning the remaining concentration the following ranking of the investigated active ingredients could be deduced: Cr (90%)> Zn (60%)> Cu (40-70%) >= F (40%) > B (concentration <10%). Furthermore the results show that the remaining content of copper differs depending on the wood preservative used. The lowest content was detected for the CCZnF-formulation, the highest for the copper-quat-preservative. Furthermore it is obvious that the rate of biological decay correspond well with the distribution of the wood preservative components in the segments.
E Melcher, H-W Wegen
Standardization of preservative treated timber species for conductor, insulator and transformer packing of REB
1996 - IRG/WP 96-40071
In order to resolve the post landing failure problem of wooden packing for conductor, insulator, transformer of REB, the names of the suitable timber species from different parts of the world, irrespective of countries of origin have been standardized along with their strength and treatability grades. The CCA treatability of some Pakistani timber species have been presented for example which was treated at high impregnation pressure with low moisture (12% MC) and low concentration (1.5% W/V) of CCA-C (chromated copper arsenate type-c, oxides) and was analyzed spectroscopically for finding out the dry oxide retentions (W/V & W/W%) of individual components of CCA-C as well as chemical balance.
A K Lahiry
Chitosan for wood protection - state of the art
2005 - IRG/WP 05-30378
The aim of this paper was to give a state of the art description of chitosan as a wood protecting agent. Chitosan is a metal free natural compound derived from crustacean shells and is under evaluation as an environmentally benign wood protecting agent. Information from journals states that chitosan may act both fungistatically and at higher concentrations, as fungitoxic, but the mode of action is not yet fully understood. The hypothesis with most support in the literature is that chitosan interacts with the cell membrane and causes alterations in permeability. It is not proven that chitosan is more effective against a particular class of fungi, but morphological changes and reduction in growth rate is reported from a range of fungi. Results from agar plate growth rate tests are not conclusive with respect to whether high or low molecular weights are most effective against micro-organisms. Other factors than the molecular weights may influence microbial activity of the species studied, i.e. FA, pH, and internal distribution of the monomers, concentration and additives. In results available in the literature it is obvious that there is a dose-response relationship between chitosan and antimicrobial activity. In agar plates a lethal/totally inhibiting concentration is usually between 0.1 and 1 %. Chitosans in solution are more effective against antimicrobial growth than chitosans in suspension (i.e. solid chitosan particles). This is further reflected in that higher concentrations of chitosan are needed in wood than in agar amended plates. If the treated wood is subjected to leaching, around 5 % (w/v) chitosan solutions seems to be needed for good efficacy against fungal decay. Some tests where chitosan fails in decay tests are probably because of the use of to low concentrations, or to low penetration of chitosan solution due to high molecular weight.
M Eikenes, G Alfredsen, E Larnøy, H Militz, B Kreber, C Chittenden
Differences in pH, electrical resistance, cation composition and NIR spectra of red spruce wood during early stages of brown rot degradation
2002 - IRG/WP 02-10449
Red spruce sapwood was exposed to degradation by the brown rot fungi Coniophora puteana, Postia placenta, Gloeophyllum trabeum and Serpula lacrymans for 0, 1, 2 or 3 weeks using a modified soil block assay design. Average weight losses over time ranged from 0-8.9% during this time period. Detectable changes in pH, electrical resistance and cation compostion were observed in the wood as early as 1 week. The magnitude and temporal patterns of these changes varied with the species of fungus. Near Infrared (NIR) spectroscopy was used to predict degradation with good reliability even at early stages of degradation (2-4 weeks). Principal component analysis (PCA) of the NIR spectra was used to differentiate among early decay stages associated with the four brown rot fungi tested.
J Jellison, S Kelley, B Goodell, D Hui, A Ostrofsky
Site characteristics impacting historic waterlogged wood: A review
2000 - IRG/WP 00-10344
Survival of waterlogged wood from hundreds and in rare cases millions of years presents scientists with a unique opportunity to examine wood specimens which, due to select properties of the wood itself and/or the depostional environment, have not been completely degraded. Although degradation patterns of various types of microbial wood decay have been studied in detail, the site parameters of the zone from which the wood was removed has not been systematically characterized and correlated to the specific types and cause of degradation. Studies have been conducted attempting to relate factors such as hydrogen-ion concentration (pH), redox potential (Eh), oxygen (O2) concentration, and chemical end-member concentration to specific environments, but there has been no unification of testing methodology. This paper proposes to review the literature concerning site characteristics that impact the biodegradation of historic submerged wood, and discuss the implication of such research to future needs for further advancement of the science.
B A Jordan, E L Schmidt