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Soft rot decay in acetylated wood. Chemical and anatomical changes in decayed wood
2002 - IRG/WP 02-40231
Acetylated Beech (Fagus sylvatica) and Scots Pine (Pinus sylvestris) wood were studied in soil beds under laboratory conditions for longer periods. High mass losses and dynamic MOE losses were measured in non-acetylated wood and at lower weight percent gains (WPG). Rapid losses of lignin, holocellulose and ?-cellulose occurred in non-acetylated beech wood and no losses were detected at the highest WPG. Changes in chemical composition of acetylated beech wood at lower WPGs was measured. Slight changes in chemical composition of non-acetylated Scots pine wood were also observed and minor changes in acetylated wood at all WPGs; except in holocellulose. An intensive anatomical study was performed by light microscopy and SEM microscopy. The results are presented and discussed. Results showed a significant prevention of acetylation against fungal growth above 8 % and 10 % WPGs in beech and pine respectively.
B Mohebby, H Militz


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


Durability of heat-treated wood
1999 - IRG/WP 99-40145
Heat-treated wood from the French process were laboratory tested against decay using agar block test and a modified soil block test. Water absorption, bending strength, lignin content and acid number were also determined to evaluate the effect of heat treatment. Heat treated samples exhibit a higher lignin content and a lower acid number compared to untreated control indicating the degradation of some hemicellulose and extractives compounds. The significant amount of water absorbed during water soaking or exposure to different relative humidity suggest that the heat treatment help in releasing the stress in wood after the removal of hemicellulose and degradation of lignin rather than the reported significant cross link reaction of organic acid and the benzene ring of lignin. Cubes extracted with water or acetone or chloroform and challenged with pure culture of fungus show an appreciable weight loss which confirm the absence of any extractable compounds toxic to decay fungi during the heat treatment. After 12 weeks exposure for laboratory soil block or 6 to 8 weeks for agar block test, significant weight loss was observed. For soil block test, weight loss of 11% was obtained for heat-treated samples exposed to G. trabeum and 46% for P. placenta. About 56% and 54% weight losses were obtained for southern pine control exposed to G. trabeum and P. placenta, respectively. The weight loss of water and acetone extracted heat-treated sample exposed to P. placenta was 49.7% and 53.9%, respectively. Only about 11% and 14.8% weight loss was obtained for water and acetone samples challenged with G. trabeum. The moisture content of tested sample was about 70 ±10% for the un-heated control and 50 ± 10% for heat-treated samples. This treatment may modified the durability from non resistant to moderate/resistant species depending on fungus species as defined in the ASTM 2017 standard. The data from the bending test indicate that such treatment may create a 10 to 50% reduction in MOR and deflection which will limits the use of such wood for structural purposes.
D P Kamdem, A Pizzi, R Guyonnet, A Jermannaud


Protection of wood for above ground application through modification with a fatty acid modified N-methylol/paraffin formulation
2007 - IRG/WP 07-40378
Hydrophobic chemical modification can be regarded as an alternative approach to conventional wood preservation using biocides in order to protect wood in hazard class 3 according the European Standard EN 335-1. A formulation containing fatty acid modified N-methylol/paraffin and an aluminium salt catalyst was used to change the material properties of wood in order to protect wood from fungal decay and deterioration through weathering. Beech wood (Fagus sylvatica) treated to weight percent gains (WPG) of 10-14% resulted in significant decrease in water uptake in a submersion test of 40-50% when compared to that of untreated wood. The treatment slightly reduced the equilibrium moisture content at 60% and 90% relative humidity by 2% compared to untreated wood. An anti-swell efficient (ASE) of 26.6% was achieved at a WPG of 15.7% and indicated a moderate dimensional stabilisation. Strength properties of treated wood were not reduced by the treatment. In addition to the improvement of water related properties, the durability towards basidiomycetes was highly increased (tested according to EN113); the weight loss at 15% WPG was lower than 3%. Infection by the blue stain fungus Aureobasidium pullulans was significantly reduced in a laboratory test due to the treatment. Outside exposure over 1 year revealed less cracking and blue stain compared to untreated wood. The results of this study show that wood modified with a formulation of fatty acid modified N methylol/ paraffin was able to protect wood applied in hazard class 3 according to the European standard EN 335-1 over a long time period without the application of conventional biocidal products.
Nguyen Hong Minh, H Militz, C Mai


Adsorption of ionic liquids by Scots pine wood (Pinus sylvestris L.) and beech (Fagus sylvatica L.): equilibrium and kinetic modeling
2010 - IRG/WP 10-20447
In this paper methods for the adsorption study of quaternary ammonium-based ionic liquids on Scots pine (Pinus sylvestris L.) and beech (Fagus sylvatica L) are presented. Kinetic and equilibrium adsorption of compounds were evaluated. The equilibrium data fitted very well to the Langmuir adsorption models. The highest correlation coefficients determined from the pseudo-second order kinetic model confirm the key role of chemisorptions in the process of thickening of ionic liquids on the wood surface. The bonding identification of the ammonium nitrates into the Scots pine and beech wood was carried out using IR spectroscopy.
J Zabielska-Matejuk, A Stangierska, M Kot


Extraction and analysis of DNA from green and seasoned timber as basic methods for determination of wood species and origin
2013 - IRG/WP 13-20523
Against the background of the European timber trade regulation EUTR, commenced to law by March 2013, the determination of wood species and tracing of its origin is getting a great importance. A promising approach for establishing fast and reliable tracking systems for wood products is DNA analysis. A critical point is the extraction of analysable DNA from the wood and its lignified cell walls. Thus, aim of the work was the analysis of DNA content in different areas of the cross section of green and dry, well-seasoned wood from pine, spruce and beech, using quantitative, real-time PCR analysis. DNA from green timber was successfully extracted and amplified with primer set ycf3hm at all three wood species and zones of cross-section. Whereas the results with pine and spruce confirmed the expectation, that the DNA content decreases from cambium to pith, this was not observed with beech. DNA detection with 20 year old well-seasoned wood was successful only with beech. Further systematic studies are necessary to get better information about the influence of wood processing and ageing on DNA quantity and quality.
K Jacobs, H Mende, W Scheiding


Virulence of two Laboratory Test Strains and one Natural Isolate of Rhodonia (Oligoporus) placenta against Thermally Modified Pine and Beech Wood
2013 - IRG/WP 13-20524
Rhodonia (Oligoporus) placenta is known as a relative aggressive basidiomycete fungus against thermally modified timber. In durability lab tests, this often results in a lower durability class, compared to other test fungi. In the reported work, the virulence of three different strains of Rhodonia placenta for untreated and thermally modified timber was determined and compared. Therefore, two lab strains and an isolate (sourcing from a field sample) were used for durability tests according to CEN/TS 15083-1. Complementary, Coniophora puteana and Trametes versicolor were used as test fungi. The tests were performed with untreated and thermally modified wood (180 °C, 190 °C and 200 °C) from Scots pine sapwood (Pinus sylvestris L.) and European beech (Fagus sylvatica L.). To verify the identity of the fungi species, the strains were specified by both morphological and molecular analysis, the last one based on sequencing the internal transcribed spacer (ITS) of the nuclear ribosomal DNA (nrDNA). As expected, the durability of beech and pine sapwood was considerably increased by thermal modification. Distinct differences were found between the virulence of the R. placenta strains. Generally, at all 8 material variants the isolate of R. placenta showed a higher degradation capability than the lab strains. At thermally modified pine sapwood, the isolate of R. placenta led to higher mass losses and resulted in lower durability classes than the standard test strains required by CEN/TS 15083 1. The highest mass loss at pine and beech wood, untreated or modified at 180 °C or 190 °C, was caused by C. puteana. From 190 °C to 200 °C treatment level, the durability class of thermally modified beech changed remarkably from 3-4 to 1-2, referring to all fungal strains. In contrast to the durability tests, the R. placenta isolate, as the strain with the highest virulence, showed the least cellulolytic enzyme activities, which were determined in rapid tests.
K Plaschkies, W Scheiding, K Jacobs, N Rangno


Dynamics of biofilm formation on wood impregnated with vegetable oils
2016 - IRG/WP 16-40769
Biofilms can be used as a living protective coating for wood, showing advantages compared to traditional wood-coatings regarding sustainability and self-repair. Biofilms can be formed on oil impregnated wood. Such an oil-biofilm system has the potential of protecting the wood against UV and bio degradation, creating a homogeneously black surface with self-healing properties. Results of biofilm formation from an 18 month’s field test experiment containing beech (Fagus sylvatica), yellow pine (Pinus sylvestris) and Douglas-fir (Pseudotsuga menziesii) impregnated with olive and raw linseed oil are presented in this paper. Oil treated wood samples were exposed to natural outdoor conditions on the roof of the Eindhoven University of Technology in the Netherlands. Biofilm formation was monitored by imaging the wood surface with a digital camera. Current results show that biofilm formation on olive oil and combination of beech and linseed oil was completed in a period of 1 year.
K Filippovych, H Huinink, L van der Ven, O C G Adan


Penetration behaviour of different hydrophobic carrier substances for oily wood preservatives in Beech and Scots pine sapwood
2017 - IRG/WP 17-40804
The use of creosote as a wood preservative has a long history. Current areas of application are railway sleepers, transmission poles, timber bridges and marine applications. If the approval for creosote will not be prolonged, alternative wood preservatives will be needed. As the penetration behaviour after pressure impregnation of different alternative oily products in this fields of application is so far little investigated, research has been implemented for hydrophobic carrier substances. Viscosity as one main influencing factor has been evaluated. Furthermore, the penetration behaviour in Beech (Fagus sylvatica) and Scots pine sapwood (Pinus sylvestris) after a vacuum/pressure impregnation has been analysed on macroscopic- and microscopic-level. During temperature increase, the investigated hydrophobic carrier substances showed differences in viscosity. Also differences in penetration depth after impregnation has been observed between Beech and Scots pine sapwood on macroscopic level. The microscopic analyses show the penetration pathways of the products for the tested wood species. The results will be used to optimize the impregnation processes with new oil based wood preservatives on pilot plant level as well as on industrial scale.
M Starck, A Gellerich, H Militz


An examination of the potential for the use of the Maillard reaction to modify wood
2018 - IRG/WP 18-40829
Finding efficient ways to decrease wood decay caused by fungi and increasing its dimensional stability is an important issue in the timber construction. A possible way to avoid wood decay by fungi is by reducing the water content of wood, since water is a primary condition for fungal growth. Bulking of the wood cell wall by chemical reagents occupies the space where water normally occurs. At the same time this also improves the dimensional stability of the modified wood. However, for effective protection using impregnation modification, it is a requirement that the bulking agent is located in the cell wall of the wood and is non-leachable in service. A commercially-viable process also requires a water-based delivery system, the use of impregnation agents of low-toxicity, thermal-curing and no concerns regarding toxicity at end of life of the modified wood product. The aim of the work was to react non-toxic reagents using a Maillard type of reaction in the wood cell wall. Wood was soaked in different aqueous solutions with a primary amine and a sugar as the main constituents. The wood was thereafter cured in an oven at 120°C. The preliminary results showed that the use of the Maillard reaction for wood modification is a promising method and is worth further research.
K Peeters, E Larnøy, A Kutnar, Č Tavzes, C A S Hill


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


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


Screening potential preservatives against stain and mould fungi on pine timber in Zimbabwe
1995 - IRG/WP 95-30063
The search for environmentally and toxicologically safer chemicals for use in the timber preservative industry against stain and mould fungi has been intensified during the past few years. Results of field tests with two chemicals previously evaluated in the laboratory are presented. The conventional sodium pentachlorophenate was the more efficacious chemical against stain and mould fungi, providing up 90% control at a concentration of 2.5%. A potential alternative, Stopstain a borate-based chemical, gave results only slightly better than the untreated control timber, at a concentration of 5%. Unless the environmental cost and toxicological hazards of traditional chemicals are highlighted the newer and safer chemicals will be reluctantly accepted by industry as they are regarded as being prohibitively expensive.
A J Masuka


Dimensional stability and decay resistance of hot-melt self-bonded particleboard by surface benzylated pine chips
1991 - IRG/WP 3652
Akamatsu (Pinus densiflora Sieb. et Zucc: Japanese red pine) particles were pretreated with 40% NaOH solution and benzylated with benzyl chloride, and the surface of particle was converted into meltable materials. Hot-melt self bonded particleboard having smooth and high glossiness surface was prepared by hot pressing at 150°C and 1.96 MPa without using any conventional adhesives. Dimensional stability and decay resistance of the benzylated particleboard were evaluated. Particleboards made of benzylated particles having more than 38% of weight percent gain (WPG) showed that dimensional stability and decay resistance were superior to the conventional particleboard made by using phenolformaldehyde resin as a binder, because hydroxyl groups of wood were substituted by hydrophobic benzyl groups with benzylation. Though bending strength of the board was a little lower than control board due to the damage of benzylated particles during benzylation, its internal bonding strength was very high, because the hot-melting strengthened the inter-particle bonding.
M Kiguchi, K Yamamoto


Strength loss associated with steam conditioning and boron treatment of radiata pine framing
1987 - IRG/WP 3438
The combined effect of included defects and wood moisture content on the strength loss of second rotation radiata pine framing following conventional steam conditioning is investigated. The green Modulus of Elasticity (MOE) is reduced by approximately 13% after steaming. When dried after steaming, however, neither the MOE nor MOR is significantly different from unsteamed dried controls.
M J Collins, P Vinden


Soil virulence tests using Scots pine sapwood
1973 - IRG/WP 222
Following the tests reported in Document No: IRG/WP/210, in which soils from different laboratories were investigated for virulence, supplementary tests have been carried out using Scots pine sapwood and an extended incubation period.
J K Carey, J G Savory


Types of decay observed in CCA-treated pine posts in horticultural situations in New Zealand
1984 - IRG/WP 1226
The few reported failures of 11-12-year-old horticultural posts in New Zealand in 1982 were caused by brown-rot. A subsequent survey of CCA-treated posts in all the major horticultural areas has revealed decay of many posts. A microscopic examination of these posts has shown decay by brown-rot, white-rot, soft-rot and bacteria. Several types of bacterial decay have been observed.
J A Drysdale, M E Hedley


Effect of medium-term degradation of beech wood by erosive (Phanerochaete chrysosporium) and lignin-selective (Ceriporiopsis subvermispora) strains of white rot fungi on its selected physical properties
2004 - IRG/WP 04-40292
At the Faculty of Wood Sciences and Technology a fungal delignification of normal and tension beech wood by erosive and lignin-selective strains white-rot fungi has been studied. The pre-treatment of both kind of wood samples was accompanied by partial delignification and apparent changes of their physical properties influencing the polar liquids penetration.
R Solár, S Kurjatko, M Mamonová, J Hudec


Termite resistance of pine wood treated with chromated copper arsenates
1997 - IRG/WP 97-30128
Two four-week, no-choice laboratory tests were performed with CCA-treated southern yellow pine and radiata pine against Formosan subterranean termites, Coptotermes formosanus. CCA retentions as low as 0.05 kg/m3 (0.03 pcf) provided protection from all but light termite attack (rating of 9 on a 10-point visual scale). Similar and consistent light attack on wafers containing retentions as high as 6.4 kg/m3 (0.4 pcf), coupled with complete termite mortality, demonstrates that the mode of action of CCA treatments relies upon toxicity rather than having any repellent effects against termites.
J K Grace


Durability of pine modified by 9 different methods
2004 - IRG/WP 04-40288
The decay resistance was studied for pine modified by nine methods of wood modification: 1) Acetylation, 2) Treatment with methylated melamine resin (MMF), 3) Acetylation followed by post-treatment with MMF-resin, 4) Thermal modification, 5) Furfurylation, 6) Maleoylation (using water solution of MG or ethanol solution of maleic anhydride), 7) Succinylation, 8) NMA-modification and 9) modification with reactive linseed oil derivative (UZA), Wood blocks of Scots pine (Pinus sylvestris L.) sapwood were modified in pilot plants. Methods 1-5 were performed by the authors at Chalmers University of Technology or at BFH in Hamburg. Methods 5-9 were part of a European research project (the Chemowood project, FAIR-CT97-3187) and therefore each of these modifications was performed by the project participant responsible for the method. For laboratory testing in TMCs (modified European standard ENV 807) and pure basidiomycete culture bioassays, smaller test specimens were cut from the modified wood blocks. Most of the modification methods were applied on test specimens for marine field testing (EN 275) and some methods to produce mini-stakes for field tests in five Swedish fields. Some modification methods result in modified wood with poor durability, whereas other methods (acetylation, furfurylation and MMF-treatment) seem to provide excellent resistance to microbial decay.
M Westin, A O Rapp, T Nilsson


Performance of Tebbacop in laboratory, fungus cellar and field tests
2000 - IRG/WP 00-30222
A novel organo-copper wood preservative ("Tebbacop") has been exposed to 12 years fungus cellar testing and 6 years above ground field testing. In the fungus cellar, Tebbacop at a retention of 0.053% Cu m/m oven dry wood out-performed CCA at a retention of 0.55% m/m oven dry wood. In above ground tests, L-joints treated to a Tebbacop retention of 0.012% Cu are performing as well as joints treated with TBTN to a retention of 0.08% Sn. In a slightly more severe decking test, 0.016% Cu as Tebbacop was more effective than 0.08% Sn as TBTN.
M E Hedley, D R Page, B E Patterson


Leaching of copper, chromium and arsenic from CCA-treated Scots pine exposed in sea water
2000 - IRG/WP 00-50149
A laboratory leaching trial combining a static and a flowing seawater system was carried out to measure the leaching rates of copper, chromium and arsenic from the surface of Scots pine panels vacuum-pressure treated to 3, 6, 12, 24, and 48 kgm-3 CCA. Untreated and treated panels were exposed in flowing seawater for up to 8 weeks followed by 2 weeks submersion in static seawater which was taken for analysis. The study revealed a leaching hierarchy of Cu>Cr>As which supports the findings of other investigators. Over the 8 week leaching trial there was a time-related decrease in the rate of copper and chromium loss. Over the first week of leaching in flowing seawater, the rates of loss of copper and chromium decreased to between one-half and one-seventh, followed by lower rates of leaching over the remaining period of the investigation. In contrast, the rate of loss of arsenic from the wood appeared to increase slightly over the same period. The data are compared with minimal leaching rates of toxins from the surface of anti-fouling paints and are discussed in terms of the fouling communities which are established on Scots pine panels treated to similar target retentions.
C J Brown, R A Eaton


Light organic solvent preservative treatment schedules for New Zealand-grown radiata pine
1986 - IRG/WP 3379
The influence of pressure differential and treatment time on preservative uptake and distribution in radiata pine heartwood and sapwood is investigated. Treatment schedules are defined which minimise solvent usage but ensure complete sapwood penetration and optimise heartwood penetration.
P Vinden


Creosoted radiata pine by non-pressure methods
1988 - IRG/WP 3486
Posts of Pinus radiata have been impregnated with creosote by immersion for 1, 3, and 7 days, and by hot-and-cold open tank with hot bath temperatures at 40°C and 60°C. On the basis of the retention rates obtained, suitable procedures are described for wood elements that are going to be in ground contact, and an analysis is made of the way in which the variables tested affect the results.
M V Baonza Merino, C De Arana Moncada


Light organic solvent preservative treatment of glue-laminated radiata pine
1986 - IRG/WP 3380
The high permeability of radiata pine (Pinus radiata D. Don) is associated with ray-tissue and in particular the cross-field pits linking ray-tissue to tracheids. This pathway is absent in the tangential grain direction, leading to poor preservative penetration when treatment is restricted to the radial face - for example, timber fabricated into glue-laminated beams.
P Vinden


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