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Effects of seed origin and site on both wood density and longitudinal fluid uptake of Sitka spruce (Picea sitchensis (Bong.) Carr.) with height in the tree grown in the United Kingdom
2002 - IRG/WP 02-40226
The variation in density and longitudinal fluid uptake was investigated in short specimens of wood taken from eight seed origins of Sitka spruce trees grown at two sites in the UK. Five trees of each seed origin at each site were sampled at three heights (1, 2 and 3 m above ground level). The density of the samples decreased with increasing height within the stem. This corresponded with increasing ring width. The change of the longitudinal fluid uptake from base to apex showed an inverse trend to density. Site had an effect on density and increased density reduced fluid uptake. Seed origin had a marked effect on density and fluid uptake but the two factors showed no correlation. Some seed origins showed a variety of desirable characteristics and recommendations are made for the selection of seed origins for further UK plantations based on growth rate, density, tree form and permeability.
I Usta, M D C Hale
Comparison of permeability at different levels of moisture content in Bornmullerian fir (Abies bornmulleriana Mattf.) and Eastern spruce (Picea orientalis L.) impregnated under vacuum/pressure through full-cell method by using CCA and CCB of different concentrations
2007 - IRG/WP 07-40366
In this study, a comparison has been made in terms of the combined, longitudinal, tangential, and radial permeability of the species of Bornmullerian fir (Abies bornmulleriana Mattf.) and Eastern spruce (Picea orientalis L.) with moisture contents of 50 % and 15 %, which were impregnated under vacuum/pressure through full-cell method by using water-borne wood preservatives (impregnation materials) of Tanalith-C (CCA : copper-chromium-arsenic) and Wolmanit-CB (CCB: copper-chromium-boron) in concentrations of 2.5 % and 3.0 %. The experimental data obtained were examined in terms of the wood species concerned, level of moisture, type of the impregnation material used, concentration of the solution and the direction of the liquid flow, by taking as basis the level of absorption of the two different impregnation materials by the cell cavities of the wood species tested. Results of the tests made by using the impregnation materials of CCA and CCB in different concentrations (2.5 % and 3.0 %) have shown that the level of absorption (in the species of Bornmullerian fir and Eastern spruce) was the highest when the wood was dry (with a moisture of 15 %); and that when the wood was wet (with a moisture of 50 %), absorption of the wood preservative liquid was the highest in both of the species particularly when CCB is used. The results of this study have also revealed that the level of absorption of the impregnation material under all the experimental conditions was higher in the wood of Bornmullerian fir, compared to that of the Eastern spruce. The analyses made by using different concentrations of the impregnation materials have shown that in general, the impregnation materials of lower concentrations were absorbed relatively better by the wood, based on the direction of the liquid flow. In order to see the level of absorption of the impregnation materials, the amounts of liquid flow in different anatomic directions were compared in both species, and it was seen that under all the experimental conditions, the decreasing order of absorption according to direction was: combined>longitudinal>tangential>radial.
Developments in the protection of wood and wood-based products
1980 - IRG/WP 340
Technology is playing an increasingly important role in the field of wood protection. This current review highlights how modern techniques have provided greater insight into the biological and physical processes affecting the durability of wood and wood-based products. Emphasis is also given to developments in preservative testing methodology and to the encouraging changes towards both the correct use of timber and the improvement of Standards and Codes of Practice. A final section, on recent technical developments in wood preservation, considers subjects ranging from an evaluation of new specific biocides to methods of increasing the permeability of refractory timber species.
J M Baker
A review of the configuration of bordered pits to stimulate the fluid flow
2005 - IRG/WP 05-40315
As the bordered pits have generally been thought to have an influence on the refractory nature of softwoods, structural behaviour of this conducting pathways is discussed according to the published literature. Various theories on the role of bordered pits to axial flow are expounded in respect to preservative treatment. Pit aspiration is also reviewed.
Direct measurement of fluid flow within wood
1986 - IRG/WP 2248
The problematics of fluid flow mechanism within wood using a permeability concept are highlighted, and the non-feasibility of a practical and versatile model is explained. An alternative method using a negative temperature coefficient thermistor to measure flow velocity directly is presented. The method has been verified in living trees and shows extreme sensitivity for flow above 1 meter/hour. For measuring lower velocities, the method needs improvement.
J P Hösli
Time dependent over-uptake of etherificated melamine resins
1998 - IRG/WP 98-40109
Waterbased methanol-etherificated melamine-formaldehyde resins can increase the fungal resistance of the treated wood though they are known to be non-toxic. Therefore melamine-resins are at the present an object of research activities of European projects and of some companies. The paper highlights the importance of quoting the duration of the diffusion when immersed in the treating solution, as major differences in the effectiveness against fungal attack can be obtained by extending the diffusion period. This paper also critically reviews the practice of referring the concentration of the solutions used for impregnation to a fixed solids content of this type of resins.
D Lukowsky, R-D Peek
Analysing the characteristic role of moisture content for drying and fluid flow in Sitka spruce. - Part 1: The drying process of sapwood and heartwood of two different thickness of Sitka spruce using a kiln. - Part 2: Effects of moisture content on longitudinal permeability of Sitka spruce in vertical variation of the tree
2000 - IRG/WP 00-40173
The characteristic role of the moisture content in Sitka spruce (Picea sitchensis (Bong.) Carr.) that grown in the United Kingdom was examined by this study on the basis of (1) the reduction of moisture content in two different thickness of sapwood and heartwood by kiln drying process, and (2) the effects of moisture content to the longitudinal void volume filled of tanalith-C by the full-cell process from base (1 m) to apex (3 m) of the tree in sapwood zone. Accordingly, conclusions on indication of the drying process of sapwood and heartwood, and vertical variation of longitudinal flow with effects of moisture were listed separately: (1) Comparison of Drying Characteristic of Sapwood and Heartwood: The two different thickness (300x30x30 mm3 and 300x20x20 mm3) of sapwood and heartwood of Sitka spruce was dried using the suggested drying schedule in kiln. The reduction of moisture was schematically diagrammed according to sapwood and heartwood stakes. The reduction of moisture followed the same downward trend that sapwood (S) loses more moisture than heartwood (H) although the small stakes of S and H lost moisture rapidly compared with the large ones. (2) Vertical Variation of Moisture Content and Longitudinal Permeability: The 90 kiln dried defect free sapwood stakes (150x25x25 mm3) of Sitka spruce was taken from base to apex of the trees at 1, 2 and 3 m above ground level. After having the determination of moisture content in each experimental stake, the treatment was carried out by the full-cell process with CCA preservative (Tanalith-C) using a model pressure treatment plant. Significant differences observed among the tree heights from 1 to 3 m showing that slightly increases of moisture content from base to apex and conversely decreases of longitudinal void volume filled by preservative fluid.
A behaviour of CCA penetration of fir (Abies bornmulleriana Mattf.) at different ramp times and constant vacuum/pressure applications
2006 - IRG/WP 06-40346
A behaviour of CCA penetration of Bornmulleriana fir (Abies bornmulleriana Mattf.) at different ramp times and constant vacuum/pressure applications was illustrated for the main flow directions by the experimental pictures.
I Usta, R Despot, M Hasan
Effects of timber surface properties and dipping conditions on uptake of antisapstain actives from two aqueous suspensions, and ultimate effects on efficacy against mould and staining organisms
1995 - IRG/WP 95-30073
Green-off-saw rough sawn Pinus elliottii (slash pine) boards were dipped in aqueous suspensions of two antisapstain formulations, and the resultant surface retentions of active ingredients MTC (methylene bisthiocyanate), CTL (chlorothalonil) or TCMTB (2(thiocyanomethylthio)benzothiazole) were monitored by chemical analysis. Surface retentions increased with suspension concentration and surface roughness, and decreased with initial timber moisture content. Dipping time beyond 20 seconds, timber basic density and earlywood content had little effect. Relatively low surface retentions, produced by dipping smoother boards with higher initial moisture contents, provided lower protection against mould and stain during seasoning than higher retentions. Equations describing the effect of surface retention on efficacy were developed for both formulations, and retentions providing complete protection under the conditions of the test were determined.
M J Kennedy, T L Woods
Water-based water repellents for treatment of wood
1987 - IRG/WP 3446
The water uptake by wood can be reduced by treatment with a water repellent. The water repellents most commonly used are solvent based. In the present work a new type of water repellent that is water-based has been investigated. Two different treatments have shown an effect of the same order as a commercial solvent based product. The cellular distribution of the water repellents has been investigated and for one of the formulations a more uniform distribution can be seen at the impregnated surface. Use of water as a solvent would be advantageous due to lower cost and non-toxicity.
I G Svensson, G Hägglund, I Johansson, W B Banks
Technique for monitoring absorption during a vacuum pressure process
1992 - IRG/WP 92-3696
A laboratory technique was developed and an apparatus constructed which allowed for the direct and continuous measurement and observation of volumetric uptake of water-borne preservative into wood samples throughout a controlled vacuum-pressure treatment process. Fractional filling of void space was calculated. Graphing (fractional saturation) against time allows prediction of optimum cycle lengths with respect to achievable saturation values. Treatability evaluations using this technique were carried out on heartwood samples of six Malaysian hardwood species, kapur, kempas, keruing, punah, rubberwood, simpoh and on sapwood samples of Scots pine as a control. Generally the graphs exhibited two quasi-linear zones showing rapid initial absorption followed by slow absorption over a long period.
A J Pendlebury, J A Petty
Factors affecting the sorption of preservative during diffusion treatment of wood
1988 - IRG/WP 3500
The sorption of preservative into wood during soaking in aqueous solution was found to comprise absorption as well as diffusion of solute. Absorption was increased by partially seasoning the wood prior to soaking and was characterised by (a) a very rapid initial rate of uptake and (b) an extended period of slow uptake, the rate of which varied with prior conditioning. It was concluded that some partial seasoning was desirable to optimise absorption (and therefore reduce soaking times), but that extensive partial seasoning would not significantly increase the quantity of solution taken up during short soaking periods, because of the back pressure from air which tended to become embellished in the wood during soaking. The factors influencing the retention of solute following momentary immersion were identified and included: 1. Surface roughness (which may be influenced by the basic density of the wood species together with the wood sawing or machining processes used); 2. The critical surface tension of the wood substrate; 3. The solubility of the solute; 4. The surface tension of the solution. It was found that during momentary immersion the surfaces of the wood become saturated very quickly. When stored overnight under non-drying conditions however, there was movement of the solution from the surface to the coarse capillary structure of the wood. Subsequent dipping in solution resaturated the surface of the wood. Thus by a process of multiple dipping preservative retentions could be increased as though timber had been kept in the solution.
Effect of borate on uptake and efficacy of an anti-sapstain treatment
2005 - IRG/WP 05-30380
The potential for using borates to enhance uptake and efficacy of propiconazole-based anti-sapstain chemicals was assessed on ponderosa pine sapwood wafers. Borates had no consistent effect on either net solution absorption or propiconazole distribution in the wood. Even small amounts of borate, however, markedly improved the performance of propiconazole against fungal discoloration. These results are consistent with previous tests of borate addition to other fungicides and highlight the potential for using less expensive ingredients to boost the performance of more costly biocides.
Jianju Luo, Hua Chen, J J Morrell
The effect of treatment temperature on the biological performance of CCA treated wood
1990 - IRG/WP 3624
Birch and Scots pine sapwood blocks were treated with several concentrations of CCA at three different temperatures: 5, 20 and 35°C. The treated wood was maintained at the appropriate temperature for the fixation period. Leached and unleached samples were then exposed in a soft rot monoculture test using Chaetomium globosum and a brown rot monoculture test using Coniophora puteana. The treatment temperature had little effect on the performance against brown rot but the performance of birch against the soft rot improved as the treatment temperature increased particularly after leaching.
S M Gray
Novel wood modification processes for window and cladding products
2004 - IRG/WP 04-40285
Because of the low natural durability and low dimensional stability of European wood species, the usage of wood for window frames has decreased dramatically during the last decade. In a joint project of several German research institutes and the window industry, following wood modification systems were compared. heat treatment (3 different materials from 2 companies) acetylation (pine sapwood and beech wood acetylated with acetic anhydride) polymerisation (melamine resin treated pine sapwood, Interlace treatment, furfurylation) wax treatment (pine sapwood, which was impregnated with natural resin and waxes) Investigated was the moisture content, dimensional stability, capillary water uptake and the durability. The dimensional stability show a high increase for following materials: heat treated wood, acetylated pine, interlace treated wood and furfurylated wood. The melamine resin treated wood and the wax treated wood show no significant increase in the dimensional stability. The biological durability against different basidiomycetes was tested according to the EN 113. As test fungi, Coniophora puteana, Poria placenta and Coriolus versicolor were used. The results show a very high increase in the durability for most of the treated wood. The wax treated wood shows no significant increase in durability. A novel window frame consists of several functional layers. Different wood properties are demanded for the single layers to achieve optimal window properties. Every modified wood shows a special potential for the use in a functional layer.
A Krause, C Hof, H Militz
Observations on the uptake and penetration of various liquids in clear heartwood and sapwood of Pinus radiata D.Don
1983 - IRG/WP 3224
Volumetric uptake of water (aqueous copper-chrome-arsenic (CCA)) or methanol, applied by bulk hydrostatic pressure to air dried clear heartwood specimens of Pinus radiata D. Don, far exceeds that of a wide variety of polar and non-polar solvents. In air dried sapwood, the volumetric uptake of CCA tends to be less than that achieved for most solvents including methanol. No comprehensive explanation of the penetration mechanism in these two substrates can yet be offered. High temperature drying effects a significant increase of volumetric uptake of all liquids by heartwood, but not by sapwood, possibly because air dried material is nearly saturated after pressure treatment.
J E Barnacle
Alternative technologies for wood wastes recycling - Part B: Biotreatment of PCP- and creosote-treated wood
1998 - IRG/WP 98-50101-18 b
Alternative technologies have been investigated to detoxify treated wood. Two classes of organic compounds are studied. Creosote-treated wood are classified in France as dangerous wood wastes. A conventional incineration could be provided for these wood wastes but the cost of this elimination could be very high (> 2000 FFR/ton). For these reasons, we have tested two kinds of new processes as alternative ways. The developed strategy is described in this paper and illustrated by a few examples. Part B - The second one is based on an oxidative degradation of organic compounds directly in the wood: oxidative degradation by fungi. Few examples are presented in this paper. Three fungi are tested directly on treated wood. High levels of contaminants are tested around 0.6 g of PCP/kg and 3.7 g of 8 PAH/kg of wood. Few oxidation products generated by this biological treatment are identified. An ecotoxicological assessment is performed to validate this process. Technical feasibility of these developed processes as well as economic aspects are discussed,
S Legay, P Marchal, G Labat
Bending properties of TCMTB-treated Southern pine sapwood using supercritical carbon dioxide impregnation process
1997 - IRG/WP 97-40080
The effects of elevated pressure and treatment with thiocyanomethylthiobenzothiazole (TCMTB) on the bending properties of Southern pine sapwood were evaluated at pressures ranging from 1,800 to 3,600 psi. All bending properties were affected to some extent by supercritical fluid treatment. Modulus of elasticity and work to maximum load were not significantly affected by pressure levels. Modulus of rupture differed among individual pressure levels, but the effects on bending strength were less definitive. TCMTB retention had little or no effect on properties, suggesting a lack of chemical interactions between the lignocellulosic matrix and this biocide. The effect of treatment on bending properties was unexpected as previous trials on smaller specimens and selected composite panels had shown no negative effects. Further trials of other wood samples with increased replication are planned to more fully understand potential treatment effects on strength properties.
Gyu-Hyeok Kim, S Kumar, E S Demessie, K L Levien, J J Morrell
Comparative moisture uptake of Douglas fir and radiata pine structural lumber when exposed to rain wetting as an indicator of relative decay resistance
2004 - IRG/WP 04-20285
Trials were undertaken to determine the relative resistance of radiata pine and Douglas-fir to wetting when exposed to the weather. Douglas-fir samples were obtained from one Central North Island and three South Island sources and had a heartwood/sapwood mix typical for each resource. Radiata pine sapwood and heartwood samples were obtained from a Central North Island source. Material was exposed to the weather as horizontal studs in the first trial, and as horizontal and vertical studs in the second trial. The first trial ran over later winter from 29 July to 22 September 2003; the second, and more comprehensive investigation, from 22 October to 17 December 2003. In the first trial, after seven days exposure, radiata pine reached a moisture content which would sustain decay (~27% mc), and remained well above that moisture content for the remaining 48 days of the trial. However, the maximum moisture content attained by Douglas-fir throughout the trial was only 21.8 % mc. In the second trial, radiata pine sapwood rapidly attained a moisture content conducive to decay, and Douglas-fir did not. Because of the warmer and sunnier weather, fluctuations in moisture content were more pronounced than in the winter trial. Samples exposed horizontally attained higher moisture contents than those exposed vertically, irrespective of wood species or relative heartwood/sapwood content. It is concluded that Douglas-fir timber shows significant positive differences from radiata pine in terms of susceptibility to moisture uptake. This trial confirmed the ‘refractory’ reputation of Douglas-fir, and the ‘absorbent’ reputation of radiata pine. At a practical level, Douglas-fir heartwood and sapwood can be regarded as equally impermeable, and independent of where in New Zealand it was grown.
M E Hedley, G Durbin, L Wichmann-Hansen, L Knowles
Dip-diffusion of dressed timber - Effect of drying
1989 - IRG/WP 3509
The effect of drying on dip-diffused dressed freshly sawn timber was determined by the depth of penetration of boron achieved on the two test timber species, White cheesewood (Alstonia scholaris) and Light Hopea (Hopea papuana). The results obtained showed that light density White cheesewood was completely penetrated even after 3 days drying while Light hopea, treated immediately achieved 5.2 mm penetration after 2 days diffusion and subsequently better after 14 and 21 days diffusion. Adequate penetration was only achieved after 14 and 21 days diffusion when there was delay between 30 minutes and 72 hours.
H C Konabe
Moisture uptake and volumetric swelling as probable factors also affecting leaching in CCA-treated wood. A preliminary study of treated Eucalyptus saligna sapwood
2003 - IRG/WP 03-30318 IRG/WP 03-30318
A number of factors affecting leaching of CCA from treated wood have been variously investigated and discussed. However, the possible effects of moisture movement in treated timbers on leaching have not received attention yet. The present study examines and compares moisture uptake and volumetric swelling in CCA-treated and untreated sapwood of Eucalyptus saligna, and tries to establish a correlation between the mechanics of moisture movement, swelling and shrinking, and leaching. Small samples of E. saligna sapwood were air-dried to 12% MC, pressure-treated with CCA-C (oxide) at a commercial treatment plant, conditioned for 28 days, leached in static water, re-dried to 12% MC and average retentions (8.2 Kg/m3) calculated on a weight-gain basis. The samples were divided into two batches, including untreated controls, oven-dried to constant weight and weights recorded. One batch of samples (including controls) was soaked in de-ionised water until water-saturated, and moisture uptake calculated on a weight-gain basis. The second batch, including controls, was measured to calculate oven-dry volumes. They were then similarly water-saturated, removed, measured and volumetric swelling computed. Water-saturation increased the MC of the treated samples to 67.69% on average, compared to 89.29% in untreated samples. Volumetric swelling in treated samples was similarly lower (6.19%) than in untreated controls (6.59%). However, both moisture uptake and volumetric swelling were significant in treated samples. Exposure to conditions of alternating wetting and drying, as in soils, with intermittent moisture uptake and release, and resulting swelling and shrinking may accelerate removal of CCA from treated timbers, and allow faster microbial colonisation and degradation of the wood. High leaching of CCA and early microbial attack, especially bacterial and softrot fungal attack, is common in CCA-treated timbers exposed to wet soils, where a higher volume of treated timber is normally used. It is probable that leaching of CCA from timbers exposed to soils is accelerated by movement in the wood caused by intermittent moisture uptake, swelling and shrinking.
Service life of pressure treated deckings of spruce in direct contact with the ground
1988 - IRG/WP 3463
For decking outdoors in Sweden, pressure treated Scots pine (Pinus sylvestris L.) is used, on account of its treatability. The feasibility of using instead the refractory Norway spruce (Picea abies Karst.) is tested in a field trial. The spruce decks were treated together with pine decks with an ordinary Bethell process. As yet, after more than four years of exposure, neither in the battens nor in the slats of the treated spruce decks any visible sign of decay has been observed. The status of the deckings is followed up with observations of the moisture content and with Pilodyn measurements of the depth of penetration of the striker pin. The pressure treated spruce material has a consistently lower moisture content and mostly also a lower penetration depth of the Pilodyn striker pin than other untreated material.
J B Boutelje, T Sebring
Contradiction between uptake of preservative in practical situation and laboratory testing
1992 - IRG/WP 92-2392
By brush treatment water- and solvent-based products were applied on boards of Scots pine and Norway spruce to achieve an uptake of 100 and 200 g/ml. In addition the scope of work to achieve the required uptake of preservative was determined under practical conditions for both product groups. EN 113 (RAL-GZ 830) tests were carried out to test the biological efficacy of products. After 18 months exposure to outdoor weathering, physical tests were carried out to evaluate the properties of the paint-film. Results of physical tests show the influence of binder-type, binder-content and paint-system on the long term stability of products. The scope of work to achieve an uptake of 100 and 200 g/m² for solvent based products is approximately two times higher than for water based products. EN 113 (RAL-GZ 830) tests with solvent based products demonstrate that contrary to water based products, the amount of applied preservative has a considerable influence on the results. Weight loss measured in accordance to the RAL-GZ 830 regulations demonstrates that for nearly all solvent based products an uptake of 100 g/m², for water based products an uptake of 200 g/m² were sufficiant to protect the wood against Gloeophyllum trabeum. Except for three tested products with an uptake of 200 g/m² neither product protects the wood against Poria placenta.
R Gründlinger, O Janotta, M Melzer
Determination of absorption, accumulation and transport of copper in mycelium of some wood decay fungi
1999 - IRG/WP 99-10323
Copper compounds are common wood preservatives. However, tolerance of some wood decay fungi to copper compounds has been observed recently. Therefore, we tried to elucidate possible causes of this phenomenon. We investigated uptake, accumulation and secretion of copper in the mycelium of potentially copper tolerant fungi (Antrodia sp.) and non tolerant fungus Trametes versicolor. We observed that potentially tolerant fungi have lower uptake of copper to the mycelium than non tolerant species. They also do not transport copper into the medium. That means that copper tolerance of fungi is probably based on low uptake of copper to the mycelium and not on the active transport from the mycelium to the medium.
F Pohleven, S Breznikar, P Kalan, M Petric
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