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Soil-bed studies (Part 3): A cause of failure of multisalt preservatives following soil-bed exposure
1983 - IRG/WP 3261
P Vinden, J F Levy, D J Dickinson


Examen chimique du traitement de poteaux effectué à St-Michel s/Meurthe
1974 - IRG/WP 337
J Guillemain-Thévenot, C Jacquiot


Literature survey on the permanence and distribution of salt-type wood preservatives
1969 - IRG/WP III 1B
The objective of this survey is generally to review some of the more important published work dealing with the distribution and permanence of salt-type waterborne wood preservatives in treated timber. The survey is limited to the major chrome-containing formulations and the classification system proposed by Becker (1964) has been adopted throughout. CK - chromium, copper (copper, chrome); CKA - chromium, copper, arsenic (copper, chrome, arsenate); CKB - chromium, copper, boron (copper, chrome, boron); CFK - chromium, fluorine, copper (copper, chrome, fluorine); CFA - chromium, fluorine, arsenic (fluor, chrome, arsenate); CF - chromium, fluorine (fluor, chrome). The literature compilation covers the performance of these preservatives assessed from laboratory tests, field tests and practical experience; their application and distribution in the treated wood; and their influence on materials such as glues, paints or metals and the wood itself. It is not the purpose of this survey to draw conclusions regarding the relative merits of the various formulations, the choice of a formulation in a given situation depending upon many factors outside the terms of reference of this review, and not all of a technical nature. In general, there is insufficient directly comparable data for a definitive assessment and in the few comparisons available special factors frequently apply.
Anonymous


Retention and distribution of copper/chrome/arsenic (CCA) in pressurised sap-displaced UK grown spruce and pine
1986 - IRG/WP 3366
Increment cores were taken from UK grown Scots pine (Pinus sylvestris L.), Corsican pine (Pinus nigra var. maritima Ait), Sitka Spruce (Picea sitchensis (Bong) Carr), and Norway spruce (Picea abies (L) Karst) distribution poles treated by pressurised sap-displacement using a 1.8% copper, chrome, arsenic (CCA) solution. Each increment core was sectioned radially and the copper, chrome, and arsenic content analysed. All four wood species showed a higher CCA content in the outer sapwood which declined radially towards the centre of the pole. The net preservative retention in the outer sapwood of Scots Pine, Corsican Pine and Norway Spruce was in the range 13-23 kg/m³. The CCA content in the outer sapwood for Sitka spruce was low (in the range 4-7 kg/m³). Little longitudinal variation in CCA content occurred along the length of the poles for the four wood species studied. The concentration of the individual CCA components varied in a radial direction. Chrome and Arsenic concentrations were at a maximum in the outer sapwood in all four wood species whereas Copper tended to be in a maximum concentration in the inner sapwood some 20-40 mm from the pole surface. This effect was particularly noticeable in Scots pine and Corsican pine. It is believed that the preservative gradients reported may be important in determining the performance of treated wood and as such should be taken into account when designing predictive tests of the efficacy of preservative treatments.
P D Evans, G M Smith, B King


A Soil Bed Test of the Effect of CCA Penetration on the Performance of Hem-fir Plywood
2004 - IRG/WP 04-30332
An accelerated decay test was set up to compare the performance of CCA-treated Western hemlock/amabilis fir plywood treated to meet the preserved wood foundation (PWF) retention standard with various patterns of preservative penetration. Short lengths of treated plywood and comparable untreated material were installed in a soil bed. After eleven years of exposure, the CCA treatments were all sound regardless of penetration, while the untreated material had failed due to decay within three years.
P I Morris, J K Ingram


Preliminary study on relation of wood structure to copper/chrome/arsenic (CCA) distribution in kempas (Koompassia malaccensis)
1995 - IRG/WP 95-40054
Kempas had been treated with copper/chrome/arsenic (CCA) preservative using full cell process. Analysis of preservative distribution at the micro level in relation to wood structure was carried out using scanning electron microscope (SEM) and energy dispersive X-ray (EDXA) analysis. The results showed that CCA elements were detected in all wood tissues at different ratios. Distribution of chemical elements appeared to be much greater in the tangential longitudinal section (TLS) than the transverse section (TS). Though the amount of chemical elements had not been quantified from the radial longitudinal section (RLS), the SEM observations showed a high distribution of chemical precipitate. In all the wood tissues observed, Cr appeared in highest amount. The precipitate analysed by EDXA, showed As in greater amount than Cr or Cu. Silica content was highest in fibres and rays as determined by EDXA but could not be detected in structural form under SEM or light microscope.
S Ani, S Salamah


Anatomical Characteristics to the Distribution of Water-borne Copper Wood Preservatives in Wood
2004 - IRG/WP 04-40277
The objective of this study was to understand the micro-distribution of a copper-based preservative in wood in connection with anatomical morphology and to consider the fixation of copper in wood. Bulk specimens and semi-ultra thin sections (0.5µm) obtained from Japanese cedar were treated with a CuAz preservative solution. After fixation, SEM-EDXA was used to investigate the micro-distribution of copper. In sapwood, copper was more abundant in the compound middle lamellae than in the secondary wall in both earlywood and latewood, and also concentrated in the tori. Copper was most concentrated as crystalline deposits in longitudinal parenchyma cells. Semi-quantitative analysis revealed the copper amount to increase in this order: secondary wall in tracheid < middle lamellae < membrane of half-bordered pit < tori in tracheid < deposits in longitudinal parenchyma cell. These different concentrations may indicate significant interactions between the amine-copper complex in CuAz and chemical constituents of wood.
H Matsunaga, J Matsumura, K Oda


Equilibrium distribution of toxic elements in the burning of impregnated wood
2001 - IRG/WP 01-50172
The current work focuses on predicting the behavior of arsenic, chromium, and copper in the burning of impregnated wood. A theoretical method is used to study the chemistry of the system, with special interest directed towards the vaporization tendency of the potentially toxic elements. The core of the study is the global equilibrium analysis that simultaneously takes into consideration all chemical reactions. The results of the present study indicate that chromium and copper are unlikely to volatilize at combustion temperatures. Arsenic appears to be more volatile. Nevertheless, the prediction showed that it may be captured by calcium of the wood ash, and small amounts are likely to dissolve in the slag-phase of the ash. It may also form non-volatile compounds with magnesium, copper, and chromium and other elements of the impregnated wood, which efficiently hinders its emissions as gaseous species.
K Sandelin, R Backman


Remedial ground-line treatment of CCA poles in service. Results of chemical and microbiological analyses 6 months after treatment
1986 - IRG/WP 3388
CCA-treated poles in service with incipient internal soft rot were remedially treated by inserting borate rods, brushing with a boron/glycol solution and injecting boric acid paste, copper/creosote paste or a commercial product (DFCK paste). The spread of active chemicals in the treated zone as well as the change in microflora have been studied with time. After six months chemicals had spread to most parts of the pole in the ground-line zone and the microflora had been changed - in some cases drastically. The test is still in progress. Chemical and microbiological analyses after 12, 28 and 60 months will be published at a later date.
B Henningsson, H Friis-Hansen, A Käärik, M-L Edlund


The non-uniform uptake of chromium and copper during the impregnation of wood using the example of a CCB-salt
1998 - IRG/WP 98-20137
The correct impregnation of wood requires among other things a regular control of the concentration of the treating solution as this and/or its stoichometric composition can change as a result of the impregna-tion process and the treated wood. The preferential uptake of individual wood preservative components by the wood is of particular importance in this connection. Dipping and vacuum impregnation of wood specimens was carried out in laboratory studies, whereby the concentrations of chromium and copper in the impregnation solution were determined before and after impregnation. In addition to this, some specimens were segmented after fixation, analysed and the ratio of the active ingredients in dependence on their penetration depth was calculated. The ratio of the constituents in the solution after the impregnation process was shown to vary from that of the initial composition. Furthermore there was a striking deficit of chromium in comparison to copper in the areas of wood near to the surface, but an excess of chromium in deeper zones. This therefore results in a comparatively greater concentration gradient for chromium which causes the wood to absorb chromium to an increased degree. It can be deduced from these results that not only the density of the solution should be analysed after certain intervals of time, but also the stoichometric composition of the impregnation agent. Further investigations will be carried out as there remain a number of unanswered questions about the increased uptake of wood preservative components (e.g. when using other treating procedures or other wood preservatives without chromium).
P Jüngel, E Melcher, R-D Peek


Distribution of copper/chrome/boron preservative in light red meranti (Shorea leprosula) before and after exposure test for 72 months
1995 - IRG/WP 95-20073
Copper/chrome/boron (CCB) preservative at 6% w/w was impregnated into light red meranti (Shorea leprosula) by full cell process. The quantitative analysis for copper, chrome and boron contents in treated wood samples was carried out by Inductive Couple Plasma (ICP). Electron Probe Microanalyser (EPMA) was used to monitor the distribution of copper, chrome and boron in the various treated wood tissues before and after exposure for 72 months.
S Salamah, S Ani


A note on the distribution of copper-chrome-boric (CCB) along the culm length of freshly felled bamboo treated by modified Boucherie process
2005 - IRG/WP 05-40317
Preservative treatment of green and dry bamboo poses severe problems. A number of bamboo/ wood preservatives (Chemical formulations) for the destroying organism like fungi, borers and termites etc. In this paper we reported preliminary results of treatment of fresh green round bamboo attached with baranches by modified Boucheri process. Sample full length of an Indian species of bamboo Dendrocalamus strictus is taken for the treatment. Bamboo culm is treated with 8% solution of copper-chrome-Boric (CCB) for 6 hours. The treatment was discontinued after six hours. When the out coming solution showed almost equivalent concentration and bamboo was removed from the equipment. Branches were removed and bamboo culm was stored under cover for slow drying to allow diffusion of salts from the vessels to the adjoining tissues. The results from the study indicate excellent penetration, retention and absorption of CCB preservative in bamboo culm.
R Lal, C N Vani


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


Diffusion and interaction of components of water-borne preservatives in the wood cell wall
1988 - IRG/WP 3474
This study investigates the rates of diffusion and ultimate distributions of copper and arsenate components of wood preservatives in wood cell walls following vacuum treatment. Adsorption studies of copper on red pine (Pinus resinosa) and trembling aspen (Populus tremuloides) wood confirm the importance of cation exchange reactions on the ultimate distribution of copper in the wood substance and its strong dependence on pH of the treating solution. Formulations containing both copper and zinc preferentially adsorb or exchange copper relative to zinc. Under high pH conditions, the arsenate anion is significantly adsorbed into the cell wall. The combined adsorption and fixation of low pH CCA solutions is much slower than adsorption of high pH ACA and CZA formulations, but the reaction with wood is more complete. Diffusion coefficients were estimated for the movement of copper and arsenate components of ACA in cell wall material of both aspen and pine sapwood using a simple membrane model for non-steady state diffusion. The longer diffusion paths inherent in the diffuse porous hardwood (aspen) resulted in much slower equalization of the solute in the cell wall matrix than in red pine. However, in both species, equalization was achieved in a relative short time compared to accepted fixation times for conventional waterborne wood preservatives.
P A Cooper


Microdistribution of Copper in Copper-Ethanolamine (Cu-EA) Treated Southern Yellow Pine (Pinus spp.) related to density distribution
2004 - IRG/WP 04-40270
The relationship between copper absorption and density distribution in wood cell walls was investigated in this study. The density distribution on layer level was obtained from two approaches: (1) calculation by using data obtained from literature; (2) microdistribution of carbon and oxygen atoms in the wood cell. The microdistribution of carbon and oxygen in untreated southern yellow pine (Pinus spp.) sapwood, as well as copper in cell walls of copper-ethanolamine (Cu-EA) treated wood was determined by scanning electron microscopy coupled with energy dispersive X-Ray analysis (SEM-EDXA). Both approaches for density distribution led to the same result: the density was higher in the compound middle lamella (ML) and cell corners (CC) than in the secondary wall. The concentration / intensity of Cu, C and O in the cell wall follow the same trend as the density distribution; suggesting that density may play a major role in SEM-EDXA study of the distribution of metal-containing wood preservatives within the wood cell wall.
Jinzhen Cao, D P Kamdem, E Pasek


The micro-distribution of copper/chrome/arsenate in Acer pseudoplatanus and Eucalyptus maculata
1973 - IRG/WP 319
The excellent field performance of copper-chrome-arsenate (CCA) treated timber has been accepted for many years. The preservative loadings used in practice have been based on field trial results, backed by service tests. The performance of treated hardwoods in trials and practice indicated that provided the required loading and penetration could be achieved the performance would be good. Recent unexpected failures in a few hardwoods treated to specification indicate that some hardwoods behave differently in ground contact from the normal test species with equal preservative loadings. Field evidence with creosote suggests that some discrepancies can occur with other preservatives as well. The immediate problem is confined to a vary few species and in all cases failure has been due to soft-rot at the ground line. Petty & Preston (1968) demonstrated that CCA preservatives penetrate deeply into the tracheid wall of conifers affording excellent protection to the timber. It was decided to investigate the micro-distribution of CCA preservative components in two problem hardwood species, Acer pseudoplatanus and Eucalyptus maculata. If the components were found to be distributed less uniformly than in softwood tissues this could possibly account for the unexpected field performance of these hardwoods in ground contact.
D J Dickinson


Fixation of chromated wood preservatives through technical drying
1990 - IRG/WP 3623
Twin samples of sawn timber of Pinus sylvestris and Picea sp. were treated with copper-chromate-containing wood preservatives and subsequently kiln resp. air dried. After drying, the distribution of preservative and rate of fixation were determined. Drying of freshly treated wood in a condenser type kiln at temperatures of 60°C and 80°C and in a vacuum type kiln at 55°C with a pressure of about 200 hPa leads to an almost complete fixation of copper-chromate-containing wood preservatives after about 70 to 100 hours resp. 10 hours depending on the drying schedule applied. In the course of drying the amount of preservative increases on the wood surface. Chromium from treated wood was not found in the "condensate" of the condenser type kiln. Further experiments are ongoing with the vacuum type kiln for collection and analyses of "condensate".
R-D Peek, H Klipp


Interactions between soft rot fungi and CCA preservatives in Betula verrucosa
1988 - IRG/WP 1367
Ultrastructural investigations were carried out to obtain information on the cell wall distribution of CCA elements during soft rot decay of 4% K33 CCA preservative treated birch (Betula verrucosa) wood. TEM observations on fibres at various stages of S2 cavity formation by mutabilis showed a distinct pattern of electron dense materials to occur within the S2 cell wall region. These materials (granular and fibrillar) were observed either concentrated around existing or previously existing cavity hyphae or more loosely associated within intervening hyphal S2 regions. TEM X-ray microanalytical studies on these materials showed high levels of CCA to be present particularly with the granular materials (thought to be melanin type material) associated with fungal hyphae; levels which greatly exceeded that recorded in neighbouring, but undegraded S2 cell wall regions. Lesser CCA levels were also found associated with non-hyphal electron dense fibrillar-like materials produced as a result of either true soft rot cavity formation or erosion attack within S2 fibre cell walls. X-ray studies on cavity hyphae has so far shown only significant levels of copper and possibly arsenic to have been taken up, and to be located in both the ground cytoplasm (only Cu) and in electron-dense bodies (Cu and As). The distribution of CCA in the degraded wood cell walls is discussed with respect to both the decay pattern, metal resistance of the fungus and the known biochemical nature of the attack process by soft rot fungi. Aspects of extracellular CCA detoxification by Phialophora mutabilis and other soft rot forming Phialophora species are further considered.
G F Daniel, T Nilsson


The Effect of Wick Action upon Moisture Distribution in Ellagate Treated Pinus radiata Wood
2006 - IRG/WP 06-40328
Sapwood stakes of Pinus radiata D. Don were treated with water-soluble tetraguanidinium, tetracholine and tetrakis-benzyltrimethylammonium ellagates. The effect of these treatments upon moisture distribution was investigated by wick action. Given that chemical reactions within the wood substrate between nutrients and treatment solutions may alter the properties of the wood with regard to moisture distribution, the presence of Cu2+ in the system was also examined. Incomplete saturation of the stakes, due to air embolism within the wood, was noted after 92 days of soaking. Percentage saturation was dependent upon the ratio of moisture uptake to moisture loss. Saturation was greatest at the base and at the air/water interface of the stakes. The high moisture content at the interface was due to moisture evaporation from the top of the stakes overcoming the influence of air embolism. The effect of the chemical treatments trialed and Cu2+ upon moisture distribution in the stakes was negligible. Cu2+ was not relocated to any significant extent, it is proposed that it was fixed by the formation and precipitation of an insoluble copper-ellagate complex within the timber.
S R Przewloka, B J Shearer, J A Hann


Micro-Distribution of Metals in Wood Treated with a Nano-Copper Wood Preservative
2007 - IRG/WP 07-40360
The microdistribution of copper in southern pine treated with a newly-developed nano-copper wood preservative was examined to determine if it differed from that reported for wood treated with conventional copper-based wood preservatives. Field Emission Scanning Electron Microscopy (FE-SEM) in combination with x-ray microanalysis (EDX) revealed the presence of nano-sized copper and iron particles in treated wood. These particles ranged in size from 10 to 700 nm and were abundantly present in pit chambers and on tertiary wall layers adjacent to the lumens of tracheids and ray parenchyma cells. FE-SEM and EDX clarified that copper and iron was mainly present as separate particles. Copper was also found in wood cell walls where its concentration was slightly higher in the middle lamella than in the secondary wall layer. In this respect the microdistribution of copper in wood treated with nano-copper resembles that observed in wood treated with conventional copper-based wood preservatives. However, the presence of numerous particulate deposits of copper in voids within the wood creates a different microdistribution pattern for copper in wood treated with the nano-copper preservative compared to that observed in wood treated with current copper-based wood preservatives.
H Matsunaga, M Kiguchi, P Evans


Micro-Distribution of Micronized Copper in Southern Pine
2008 - IRG/WP 08-30479
For copper-based preservatives to be used in ground contact, penetration of copper into the cell wall is believed to be important to protect the wood from soft rot fungi. Preservatives containing soluble copper are known to do this. It is not known whether preservatives containing particulate copper will also migrate into the cell wall in sufficient quantities to control soft rot decay. An AWPA standard E11 leaching test found that leachate from southern pine blocks treated with a preservative containing particulate copper (Micronized copper quat) contained copper ions, suggesting that copper-containing particles in the treated wood slowly release mobile copper. Southern pine sapwood samples treated with wood preservatives containing soluble (ACQ-D) and particulate copper (Micronized copper quat), as well as untreated southern pine sapwood, were analyzed by Environmental Scanning Electron Microscopy (ESEM) and Energy Dispersive X-Ray Spectrometry (EDS). Copper was detected in the lumens of wood treated with both preservatives, and not in the untreated control. Moreover, the presence of small amounts of copper in the cell walls of samples treated with Micronized copper quat and ACQ-D was indicated by ESEM and EDS. This was further supported by the results of a fungal cellar test and a field stake test which demonstrated that wood treated with Micronized copper quat is resistant to soft rot attack. Future work will investigate copper mobility from particles lodged in the lumens.
R Stirling, J Drummond, Jun Zhang, R J Ziobro


Re-Distribution of Copper in the Cell Walls of Wood Treated with Micronized Copper Quat
2009 - IRG/WP 09-30506
Wood treated with copper-based preservatives to be used in ground contact may fail to inhibit soft rot fungi if penetration of copper into the cell wall is insufficient. Preservatives containing soluble copper are known to penetrate the cell wall; however, it is not known whether preservatives containing particulate copper will also migrate into the cell wall in sufficient quantities to control soft rot decay. A method was developed to accelerate and detect re-distribution of copper into the cell wall. Copper was found to re-distribute into the cell wall, presumably from cell lumen deposits, in both ACQ- and micronized copper quat-treated samples after exposure to high temperature and relative humidity. In a non-accelerated test, copper was not found to re-distribute into the cell wall in either ACQ- or micronized copper quat-treated samples after exposure in soil at 15°C for eight weeks.
R Stirling, J Drummond


Distribution and availability of preservative components in ACQ treated wood - effects of coatings and weathering
2010 - IRG/WP 10-30537
Copper and quaternary ammonium compound (quat) distributions across lumber (gradients) and availability, as measured by amount removed by intensive leaching of wood flour, were measured in ACQ treated southern pine lumber. Samples were evaluated just after treatment and stabilization, or after 3 years of laboratory storage, or after 3 years of natural weathering exposure. The objective was to investigate how the distributions of copper, quat and monoethanolamine (MEA) changed under different exposure conditions to try to explain the long terms effects of semi-transparent wood coatings to reduce leaching, even after partial failure of the coatings. In unweathered lumber, there was a slight copper gradient from the surface to the interior of the lumber and a steeper quat gradient. Analysis of specimens after 3 years of weathering exposure confirmed the effectiveness of the coatings to reduce copper and quat leaching and showed that quat leaching from uncoated samples was substantial. There was little effect of aging indoors on availability of ACQ components. However, the availability of copper was significantly reduced after 3 years of natural exposure, even after accounting for the copper that leached during weathering. It was observed that the MEA availability was greatly reduced, presumably by preferential leaching compared to copper and quat during weathering. This appears to have reduced the amount of soluble/available copper resulting in lower long term copper leaching, especially in coated samples that were protected from high copper losses by the effect of the coating. The reduced quat leaching from coated samples is attributed to the long term effectiveness of the coatings in the earlywood portions of the samples.
T Ung, M Nejad, P Cooper


Copper nanoparticles in southern pine wood treated with a micronised preservative: Can nanoparticles penetrate the cell walls of tracheids and ray parenchyma?
2010 - IRG/WP 10-30547
This study tests the hypothesis that copper nanoparticles can penetrate the cell walls of southern pine wood treated with a micronised preservative. We examined the nanodistribution of particles in tracheid and ray parenchyma cell walls using state-of-the-art HR (High Resolution)-TEM and HR-STEM (Scanning Transmission Electron Microscope)-EDX. These devices are capable of atomic-scale resolution. FIB (Focused Ion Beam) processing was used to make ultra-thin sections for electron microscopy. Our results show that FIB sectioning in combination with HR-TEM and HR-STEM is a powerful tool for observing the penetration of wood cell walls by nanoparticles or clusters of metal atoms. HR-STEM with a Cs corrector revealed that copper carbonate nanoparticles could not penetrate the cell walls of tracheids. Copper, however, is present in cell walls of tracheids as atoms or ions. In contrast, small copper nanoparticles (2.5 nm in diameter) were able to penetrate ray parenchyma cell walls. These particles were identified as copper carbonate by HR-TEM lattice image analysis. We conclude that the cell walls of unlignified ray parenchyma tissue in southern pine are accessible to copper nanoparticles whereas nanoparticles are excluded from lignified tracheid walls.
H Matsunaga, Y Kataoka, M Kiguchi, P Evans


Influence of Copper Preservative Type on Earlywood and Latewood Distribution of Copper in Treated Wood
2010 - IRG/WP 10-40507
Some of the new water based copper containing wood preservative systems use particulate “micronized” copper as the primary biocide instead of the more traditional soluble amine copper based systems. Studies were conducted to investigate how this difference in the type of copper system might impact both initial and post drying distribution of the preservatives in wood. Of specific interest was to determine the influence of the copper type on the distribution in earlywood and latewood portions of southern pine lumber, where significant differences in wood density might impact preservative loadings for the soluble and particulate systems. Our results support that the copper distributions were distinctly different between the two systems in air-dried boards, although amine copper treated boards had a similar copper distribution immediately after treatment to that observed in dry micronized copper treated boards. Both the air-dried boards treated with micronized copper and the freshly treated amine copper treated boards had distinctly higher copper concentrations in the early wood bands than in the latewood bands on a wood mass basis. After air-drying, this difference is dramatically reduced in all but the outermost growth rings in the amine copper treated boards, suggesting some copper redistribution on drying, as well as copper binding to the wood substance in direct ratio to the amount of wood substance present.
A Zahora


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