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Novel microscopic approaches to visualise chitosan within impregnated wood
2012 - IRG/WP 12-20485
Chitosan, a deacetylated product of an abundant naturally occurring biopolymer chitin, has been used in a range of applications, particularly in food and health areas, as an antimicrobial agent. In the work reported here Pinus radiata wood was impregnated with chitosan as an environmentally compatible organic biocide. It is important to understand micro-distribution of bioprotectants in impregnated wood products to properly evaluate their performance. We developed a novel microscopic techniques to visualise impregnated chitosan within wood tissues using light microscope and field emission scanning electron microscope (FE-SEM) in combination with a dye that specifically stained wood cell walls and a heavy metal stain that chemically react with chitosan. Sections were viewed with the light microscope without staining with a dye as well as after staining with the dye toluidine blue. Light microscopy was also undertaken on sections that had been stained with 1% aqueous osmium tetroxide (OsO4). For SEM observations, the sections were treated with OsO4 and then examined with the FE-SEM, first in the secondary electron imaging mode (SEI) and then in the backscattered electron imaging (BEI) mode, imaging the same areas of a section in both SEI and BEI modes. The preparation techniques employed and the combined use of light and scanning electron microscopy provided valuable complementary information, revealing that chitosan had penetrated into the cavities (cell lumens, intercellular spaces) of all sizes present within wood tissues and had also impregnated early wood cell walls.
A Singh, T Singh


Preliminary Studies on ZiBOC- A Potential Eco-friendly Wood Preservative
2005 - IRG/WP 05-30372
Over the past decade, the wood processing industry has been increasingly involved in strategies to minimize the environmental impacts of treated wood. One sign of this is the dramatic increase in the use of preservatives based on inorganic metal oxides, which fix in wood. Among such preservatives the most common is chromated-copper-arsenate. In Ascu chromium and arsenic both are carcinogenic thus in the present study a new and fixed composition of three chemicals (Copper sulphate, Zinc chloride and Sodium borate) has been used to develop an environment friendly preservative. The formulation is amorphous and water insoluble and dissolved with the help of co-solvents. Fixation study of ZiBOC in Chir and Poplar exhibited only 23.6, 13.1 and 12.1 % leachability of Copper, Zinc and Boron in Chir and 53.5, 6.5 and 5 % leachability of respective metals in Poplar. Efficient fixation of Zinc, Boron in both the species and Copper in Chir was achieved. Efficacy against Polyporous versicolar (PV) and Poria monticola (PM) a white and brown rot fungus respectively showed that 0.50% concentration of salt (3.13 kg/m3) protected Poplar completely against both the fungus as compared to control whereas PV caused 18% and PM caused 52.1% weight loss in control samples. In Chir, 0.2%(1.39 kg/m3) and 0.1% (0.68 kg/m3) concentration of salt protected blocks completely against PM and PV respectively as compared to control (54 and 11.4% weight loss caused by PM and PV). Accelerated field test after three months of installation reveals full protection of both the species against termite & fungus. Scanning electron micrograph revealed the difference of parent individual salts with the derived product. Thus, study is directed to develop synergistic biocidal compositions that combine a copper salt and inorganic biocide, removing arsenic and chromium, giving fourth generation of preservatives.
S Tripathi, J K Bagga, V K Jain


The invasion channels of damage fungi in bamboo lumber
2010 - IRG/WP 10-10712
The micro-agents on bamboo lumber damage are mould, stain, and decay fungi. This research is about invasion channels of bamboo lumber damage fungi by scanning electron microscope (SEM). The results showed that the conidia of mould were only accumulated on the surface of bamboo and no hyphae detected in bamboo vascular bundle, and hyphae of stain penetrated into bamboo and grew in metaxylem vessel, then expanded from cell to cell through the pits. The brown-rot hyphae extended in cell to cell of bamboo via pits of cell wall, like stain fungi. But branches of brown-rot hyphae were gradually increased and thicker. Hyphae formed nicks (bore holes) on lumen wall contact and then rapidly penetrated. The bore holes later enlarged uniformly. Vertical section showed that bamboo decay firstly on metaxylem vessel wall, then parenchyma cells, finally fibre.
Xingxia Ma, Mingliang Jiang, Daochun Qin


The Protective Effect of Different Tree Bark Extractives against Decay Fungi
2017 - IRG/WP 17-30707
There are various modification methods which increase the resistance of wooden materials. Due to recent environmental regulations, there is a need for new and environmentally-friendly wood preservatives. In this study, six different tree bark extractives were evaluated for their wood resistance against fungal degradation. For this purpose, the white rot fungi (Tramates versicolour) and brown rot fungi (Coniophera puteana) were used to determine the level of resistance of the tree bark extractives. The tree bark extractives demonstrated high resistance to fungi decay. Different tree bark extractives prevented fungus degradation for both fungi. SEM images also exhibited this phenomenon. The wood samples treated with extractives were covered with less hyphae as compared to the control samples. The tree bark extractives can be evaluated in a wood protection area.
Ö Özgenç, S Durmaz


SEM of wood dust particles
1997 - IRG/WP 97-50084
Dust particles from beech and oak trees have been classified in Germany as being "working materials which are definitely carcinogenic to humans". All other wood dusts, including those from softwoods, are classified as being materials "with reasonable suspicion of carcinogenic potential". The carcinogenic principle of action continues to remain unclear. The mechanical irritation is one of a number of possible triggering principles. In this connection the morphology of the dust particles is of decisive importance. With the aid of a scanning electron microscope this study characterises the dust from spruce, Scots pine, beech and oak. With regard to shape and size the dust particles of all sample collections were divided into 5 groups with principle structural similarity. Therefore a different particle morphology with correspondingly different mechanical irritation in the nose can not be the main principle of action. When compared to asbestos fibers, the small amount of fibrous dust particles as one of the five groups could be clearly distinguished by their structure and dimensions. Mechanical irritation as the main principle of action in the formation of malignant nasal tumors is also contradicted by the findings of different working groups which have established a strong association between hardwood dust and adenocarcinomas of the nasal cavity and paranasal sinuses, and a connection between softwood dust and other types of nasal carcinoma.
U Schmitt, R-D Peek, A O Rapp


Termite and fungal resistance of in situ polymerized tributyltin acrylate and acetylated Indonesian and USA wood
2000 - IRG/WP 00-30219
Wood [Indonesian pine (IP), Indonesian Jabon (IJ) and USA southern yellow pine (USP)] was either in situ polymerized with tributyltin acrylate (TBTA) or acetylated and then exposed to termite and fungal degradation both in laboratory tests and field exposure. The TBTA woods had an average weight percent gain (WPG) of 11% for IP, 12% for IJ, and 10% for USP. The acetylated woods had a WPG of 15-27% for IP, 16% for IJ, and 12-21% for USP. All levels of TBTA and acetylation treatments were effective against the brown-rot fungus Tyromyces palustris and the white-rot fungus Coriolus versicolor in laboratory testing. Resistance to subterranean termites [Coptotermes gestroi (Wasmann)] and dry wood termites [Cryptotermes cynocephalus (Light)] was shown in laboratory tests with all treatments. After one year of field testing in Indonesia (AWPA Standard E7-93), TBTA treated specimens gave a grade number of 8 for all 3 woods compared to 0 for the untreated controls (based on a 10 - point scale.) The acetylated specimens gave a grade number of 4 for IP, 8 for IJ, and 6 for USP. Scanning electron microscopy (SEM) showed polymer located in the lumen of the earlywood and latewood of selected TBTA treated specimens, but at low overall polymer weight gain the lumens were not evenly filled. Termite field testing continues on all treated wood specimens.
R E Ibach, Y S Hadi, D Nandika, S Yusuf, Y Indrayani


Studies of the ray parenchyma cell ends on the radial flow of Sitka spruce (Picea sitchensis)
2000 - IRG/WP 00-40164
It is widely accepted that either ray tracheids or ray parenchyma cells offer the major flow pathways radially for the impregnation of softwood with preservative chemicals. It is now generally recognised that, if radial flow does occur through ray parenchyma cells, the cross-field pits play a dominating role for the liquid movement in the radial direction. In this case, the radial flow of fluid is through the ray parenchyma cells to the longitudinal tracheids across cross-field pit apertures and then back again to the other ray parenchyma cells. It is in this context that cross-field pits which favours flow in the radial direction via a longitudinal route, and thus gives a long path length for radial flow. However, the presence of small channels (i.e. simple pits) between the two ray parenchyma cells may also have a recognisable influence on the radial flow, and exceed the continuous pathway for liquid movement. In this study, therefore, the anatomical structure (the end platform angle, the number of the simple pits per ray parenchyma cell end, their dimensions and the changes in dimensions across growth rings) of the ray parenchyma cell ends have been examined by scanning electron microscope (and microscopic images were then analysed by image analyser) to explain the differences in radial permeability between the extremes in the radial treatment data.
I Usta


Immuno-scanning electron microscopic localization of extracellular polysaccharidases within the fibrillar sheath of the brown rot fungus Postia placenta
1991 - IRG/WP 1497
Extracellular polysaccharidases of the brown-rot fungus Postia placenta were localized using colloidal gold labeled monoclonal antibodies to the B-1,4-xylanase (32-36kDa) fraction of Postia placenta. Postia placenta was grown from agar onto glass coverslips, immunolabeled with or without prior fixation, and examined by SEM. Enzymes were localized on the hyphal surface and on the clumped fibrillar elements (mycofibrils) of the hyphal sheath following fixation with enzymes. If fixation was omitted, labeling was diffuse and not localized on individual or clumped mycofibrils. We conclude that extracellular decay enzymes are weakly bound (non-covalently), but not identical to, the linear mycofibrillar elements of the hyphal sheath. Enzymes appear to dissociate into the water soluble glucan matrix of the sheath during incubation in physiological buffers when fixation is omitted.
F Green III, C A Clausen, M J Larsen, T L Highley


Comparison of laboratory tests and field experiments for the estimation of emissions from treated wood
2005 - IRG/WP 05-50224-6
The authorisation procedure for biocidal products according to the European Biocides Direc¬tive in¬cludes the assessment of possible environmental risks by the emission of ac¬tive ingre¬dients. This needs an input of data on the expected emissions of biocides into environmental com¬part¬ments. The procedures for the estimation of these emissions should be harmonised. La¬boratory test proce¬dures as proposed by the CEN TC38 WG27 might be a suitable means to obtain emis¬¬sion data. However, laboratory data cannot directly represent variable service con¬ditions. Only a limited number of the en¬vi¬ron¬mental conditions that can influence the emis¬¬¬sion of bio¬cides are represented in the la¬bo¬ratory tests. Never¬theless, water contact is a crucial factor for the emission of sub¬stan¬ces into water that can be controlled under labo¬ra¬to¬ry conditions. Al¬though there are only few studies that directly compare biocide emissions in laboratory and field ex¬pe¬riments it is helpful to summarise literature data for active ingre¬dients that have been ex¬ten¬sively investigated. Emission data from different types of experi¬ments are summa¬rised. Limitations and benefits of laboratory tests and field experiments as well as the resulting con¬se¬quences for the assess¬ment of emission data are discussed. Finally, it will be necessary to com¬promise about the suitability and repeatability of the test pro¬cedures and the applicability of the test results to different environmental conditions.
U Schoknecht


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


Environmental Emission of Wood Preservatives: Interpretation of Data Relevant to BPD Risk Assessments
2009 - IRG/WP 09-50259
The risk assessments for the use of wood preservatives proposed by the OECD and used under the Biocidal Products Directive (BPD) (98/8/EC) require the derivation of leaching rates for active substances. These rates are to be used as input data in to agreed exposure scenarios. The leaching rates can be derived from laboratory testing and from field testing. The relationship between laboratory and field tests has been studied in order to determine the correlation between the two modes of testing. EN84 tests have been used as a method. However, the determination of environmental leaching rates is beyond the scope of this test and it has been found to over-estimate leaching. The OECD guideline 1 (dipping) test has been designed specifically to determine environmental leaching rates from UC3 wood. This paper compares the leaching fluxes derived from OECD guideline 1 dipping tests to those derived from field tests. This allows a comparison of both the magnitude of flux rates and leaching flux profiles derived from the two tests. The magnitudes of the flux rates require the application of correlation factors in order to get agreement; these factors are presented and found to be of the order 5 – 10. The leaching flux profiles are found to be very different when the flux rates are plotted against time. The laboratory test gives an “exponential” profile, i.e. a profile that decreases quite sharply with time and then levels off. The field test produces profiles that are “sawtooth” patterns with time. This “sawtooth” pattern correlates with rainfall. This is in agreement with, and confirms, data previously presented (Baines, 2008). In the present study, however, an alternative method of data analysis is explored. If the field data is normalised according to the amount of rain falling then it is found that the laboratory and field tests produce very similar leaching profiles. Thus, the contrast previously discussed is shown to be an artefact of the method of analysing the data obtained from field tests. This is due to the inherent variability of weather patterns with time that cannot be replicated in the laboratory. If annual average rainfall figures are used, the risk assessments at differing time points can be carried out as assessments at average rainfall amounts. This alternative method of data analysis according to rainfall rather than time suggests a method of analysing the models for OECD risk assessment that can increase their utility.
D G Cantrell


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


Study of Microscopy Properties of Modified Wood During Weathering Process
2010 - IRG/WP 10-40517
In this study spruce (Picea excelsa) and Beech (Fagus orientalis) wood acetylated and has been subjected of artificial weathering in difference times (0, 50,150&300 h), then wood surface analyzed using Scanning Electron Microscopy (SEM). The SEM results shown that the surface of wood exposed to weathering undergoes distinct physical changes and the surface degradation appears to be directly proportional to the time of exposure to the weathering conditions. Changes were minor in samples weathered after 50 h. Physical changes after weathering in acetylated samples lower than un treated samples. SEM observation visualized the formation of the large surface check along the fiber lengths in the un treated specimens, but checks were dispersed over the surface with small sizes in the treated ones. The changes observed in the SEM of the surfaces after acetylated Beech and Spruce wood samples were subjected to 150 and 300h weathering are minor compared with untreated wood samples. physical changes (surface checks and color) in Beech wood is lower than spruce wood. Acetylation of the wood servers to protect the surface from the weathering effect of light and water.
M Akhtari


Decay resistance of a commercial pistachio twig-plastic composite
2011 - IRG/WP 11-40553
In this research, the decay resistance of commercial extruded pistachio twig flour-plastic composite was investigated against the white-rot fungi Trametes versicolor and the brown-rot fungus Coniophora puteana. The composite specimens containing 60% pistachio twig flour were exposed to a decay test according to modified ASTM standard for 3 months. The results showed that the composite could be decayed by the fungi. The weight loss of the composite due to decay by C.puteana was noticeably higher than that for T.versicolor. By employing scanning electron microscopic (SEM) studies, cracks and voids in the control (unexposed samples), and hyphae penetration in the sample decayed by C.puteana were shown.
M R M Farahani, M Safarzadeh


Use of Variable Pressure Scanning Electron Microscopy for in situ Observation of Degradation of Wood Surfaces during Artificial Weathering
2012 - IRG/WP 12-20489
Variable pressure scanning electron microscopy (VPSEM) is capable of observing electrically non-conductive materials like wood without the need to render the surface conductive by applying a coating of gold, platinum or carbon. Hence, there is the possibility that VPSEM could be used to non-destructively follow the structural changes occurring at wood surfaces during weathering, because specimens can be observed initially (before weathering), and then re-examined after exposure to the weather. This study uses VPSEM to examine the time-dependent micro-structural changes occurring at untreated and treated wood surfaces exposed to artificial weathering. Cryptomeria japonica (sugi) sapwood was treated by grafting a UV absorber (UVA) to the wood. We compared the micro-checking of bordered and half-bordered pits at treated (grafted) and untreated wood surfaces exposed to weathering. We hypothesised that the grafting treatment would restrict micro-checking of pits. VPSEM revealed significant micro-checking of pits at untreated surfaces exposed to artificial weathering for only 30 h. The dimensions of pit micro-checks increased when untreated samples were exposed to weathering for an additional 30 h. Pit micro-checking occurred more slowly in sugi sapwood treated with a UV absorber. We conclude that pit micro-checking at wood surfaces exposed to artificial weathering is restricted by grafting a UVA to the wood. We further conclude that VPSEM is a valuable tool to follow the time-dependent micro-structural changes occurring at wood surfaces exposed to weathering.
F Hatae, Y Kataoka, M Kiguchi, H Matsunaga, J Matsumura


Modern Instrumental Methods to Investigate the Mechanism of Biological Decay in Wood Plastic Composites
2014 - IRG/WP 14-40674
Various instrumental techniques were used to study the fungal decay process in wood plastic composite (WPC) boards. Commercial boards exposed near Hilo, Hawaii (HI) for eight years in both sun and shadow locations were inspected and tested periodically. After eight years of exposure, both boards were evaluated using magnetic resonance imaging (MRI), while a selected area of the board exposed in shadow was additionally tested using microscopy and micro x-ray computed tomography (CT). Experimental boards exposed to either exterior conditions in Vancouver, British Columbia (BC) or a laboratory decay process were used for verification of MRI and CT results obtained from the commercial board. MRI detected the presence of free water and its distribution in the exposed commercial board samples tested. Fibre saturation in the experimental board was found to be about 22%, in comparison to 27 – 30% present in most wood species. There was good correlation between the detection of free water by MRI and by destructive testing. Reconstructed volumes from CT scans of the tested boards allowed for the WPC microstructure to be observed in various planes of view and for void analysis of the material to be conducted. A significantly higher average percentage volume of voids was detected in the exposed sample compared to its reference unexposed counterpart. CT scans and subsequent void analysis of the experimental soil block culture test samples of known weight loss in wood demonstrated this technique to be reasonably accurate in the detection of voids created due to biological decay. No obvious relationship was established between the presence of free water detected by MRI and the average volume of voids detected by CT. Scanning electron microscopy (SEM) confirmed the presence of fungal mycelia in the exposed commercial board cross-section imaged by both MRI and CT. It was confirmed that both MRI and micro CT could be used for non-destructive evaluations of WPC materials, including their decay process. This work also found that many different decay fungi species could colonize and internally damage WPC, and that fungal decay in WPC seems to be a self-propagating process requiring an initiation time period where no obvious decay damage is observed.
G Sun, R Ibach, M Gnatowski, J Glaeser, M Leung, J Haight


Investigation of enzymatic effect on pit membranes by light and scanning electron microscopy
2016 - IRG/WP 16-40721
Spruce wood, one of the refractory wood species has pit membranes, which has an influence on the permeability of wood providing liquid flow between the wood cells. However, these membranes tend to close under the fiber saturated point (FSD), which makes impregnation more difficult. In this study spruce sapwood samples were treated with two different commercial enzymes to improve the permeability of spruce sapwood. Bioprep 3000 L and Viscozyme L, which are mostly used in the textile industry, are alkaline pectinase enzymes as well as acidic pectinase enzymes, respectively. Following enzymatic treatment, wood samples were analyzed under by light microscopy (LM) and scanning electron microscopy (SEM). Primarily, all enzyme treated and untreated wood samples were stained with toluidine blue. The pectin material was coloured red with toluidine blue stain. However, enzymatic treatment caused red coloration loss along with expansion and rupturing of pit membranes. According to these results, pit membranes are known to be destroyed. As expected, the acidic pectinase enzyme degraded torus more so than the alkaline enzyme.
S Durmaz, Ü C Yildiz, M Öztürk, B Serdar


Environmentally Friendly Wood Modification based on Tannin-Furfuryl alcohol - Effect on stabilisation, mechanical properties and decay durability
2022 - IRG/WP 22-40929
Furfurylation is a well-known wood modification technology. This paper studied the effect of tannin addition on the wood furfurylation. Three kinds of dicarboxylic acids, adipic acid, succinic acid, and tartaric acid, as well as glyoxal as a comparing agent, were used to catalyse the polymerisation of furanic or tannin-furanic solutions during wood modification. Impregnation of furanic or tannin-furanic solution at a certain concentration into the wood followed with curing at 103°C for a specific duration was performed for the wood modification. Different properties of the modified woods like dimensional stability, resistance of treatment to leaching, mechanical properties, decay durability against white-rot (Coriolus versicolor, Pycnoporus sanguineus) and brown-rot (Coniophora puteana) as well as their chemical and anatomical characteristics were evaluated. Results revealed that the partial substitution of FA by the tannins improved the fixation of the chemicals impregnated in wood. Further, dimensional stability, leaching resistance, Brinell hardness, modulus of elasticity/modulus of rupture, and decay durability properties of the furfurylated wood were also improved in the presence of tannins. Scanning electron microscopy revealed the polymerisation of the polymer in the wood lumen cells and in the wood cell walls.
M Mubarok, E Azadeh, F O Akong, S Dumarçay, A Pizzi, C Charbonnier-Gérardin, P Gérardin


Progress report on co-operative research project on L-joint testing
1983 - IRG/WP 2192
A F Bravery, D J Dickinson, M Fougerousse


Confocal laser scanning microscopy of a novel decay in preservative treated radiata pine in wet acidic soils
1997 - IRG/WP 97-10215
Light microscopy of radiata pine (Pinus radiata D. Don) field test stakes (20x20x500mm3) exposed in wet acidic (pH 3-4) soil for 12 - 24 months showed predominance of an unusual type of decay characte-rised by tunnelling attack of wood cell walls. After two years decay was moderate to severe in wood treated to ground contact CCA specifications and also equivalent retentions of creosote, and a number of new generation preservatives. Relative to other New Zealand temperate test sites and also an Australian tropical site, the New Zealand acidic soil test site was very aggressive. Correlative scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were used to elucidate the micromorphology of this attack. Tunnels of diameter 0.2-5 µm were present throughout all layers of the cell wall, and their orientation was not related to cellulose microfibril orientation. They also showed no preference for particular cell wall layers, indicating a lignin degrading capability. CLSM images showed that living, connecting fungal hyphae were present in the cell lumina and tunnels. This type of attack was predominant in wood that was highly saturated with water whereas wood that was less moist was predominantly attacked by classical white rot. Ongoing isolation and incubation studies in conjunction with further microscopy should enable identification of the fungal species involved.
R N Wakeling, Ying Xiao, A P Singh


A comparison of soft rot, white rot and brown rot in CCA, CCP, CCF, CCB, TCMTB and benzalkonium chloride treated Pinus radiata IUFRO stakes, after 9-15 years exposure at five test sites in New Zealand
1991 - IRG/WP 1485
The aim of this study was to determine if decay type varies significantly between five field trial test sites of different soil type, aspect and climate in 9-15 year old, replicate CCA, CCF, CCP. CCB, TCMTB and AAC treated IUFRO stakes. A visual on-site assessment of decay type on every test stake was made and observations confirmed by microscopical examination. Regression analyses were used to determine significant differences of percentage frequency of occurrence of each rot type between sites and preservatives. Large differences in percentage frequency of occurrence of rot type were evident between sites. One site was dominated by brown rot (85%) and two were dominated by soft rot (99 and 91%). The fourth site had intermediate proportions of brown rot (40%) and soft rot (71%) but had the second highest occurrence of white rot (32%) (highest = 37%; lowest = 11%). The fifth site was distinct in that a large proportion of stakes (69%) had both well established brown rot and soft rot. Stakes at the other four sites tended to have only one rot type. Some highly significant preservative effects were also found. Possible causes of these differences are discussed in terms of inter-site soil type, climate and other differences.
R N Wakeling


Field trial with poles of Scots pine treated with six different creosotes
1996 - IRG/WP 96-30115
In the middle of the 50's field trials with creosote-treated poles were started in France, Germany and Sweden. The trials were initiated by WEI (Western-European Institute for Wood Preservation). Six different creosotes were used and 40 poles per creosote were installed at each test field. Results after 39 years of exposure in Simlangsdalen, Sweden are reported. Poles treated with a heavy creosote were less decayed than poles treated with medium-heavy creosotes. Poles treated with a light creosote were most decayed.
Ö Bergman


Wood preservatives: Field tests out of ground contact. Brief survey of principles and methodology
1976 - IRG/WP 269
This paper contains the following spots: 1.: The general need for field tests. 2.: Interests and limits of field tests in ground contact. 3.: Various methods in use for out-of-ground contact field tests. 4.: Fungal cellar tests are they an alternative to above-ground decay exposure tests? 5.: Conclusions.
M Fougerousse


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