Your search resulted in 183 documents. Displaying 25 entries per page.
Changed susceptibility of the chemically and thermally degraded spruce wood to its attack by the dry rot fungus Serpula lacrymans
1999 - IRG/WP 99-10322
In buildings, some intentional or unintended situations can occur at which some wood products are exposed to aggressive chemicals and also to higher temperatures. Occasional activity of fungi on such pre-attacked wood products can be either higher or lower. This paper deals with changes in the susceptibility of spruce wood (Picea abies L. Karst.) to attack by the dry rot fungus Serpula lacrymans, in such situations, when the wood samples 8.5x8.5x120 mm3 (RxTxL) were first pre-treated with 1% water solutions of selected acids (H2SO4, CH3COOH), bases (NaOH, NH4OH) or oxidizing agent (H2O2), or they were also exposed to a higher temperature (190°C/3h). The activity of S. lacrymans was totally restricted only in one situation, if the wood was pre-treated with sulphuric acid and then exposed to 190°C. On the other hand, specimens pre-treated with ammonium hydroxide were more susceptible to bio-attack (in both situations: without or with high temperature pre-treatment effect) than sound ones.
Preservative treatment of Pinus elliottii
1987 - IRG/WP 3435
The treatment of Pinus elliottii with copper-chrome-arsenic preservative by four alternative seasoning and treatment methods is investigated. Steam conditioning followed by either alternating pressure method (APM) or 'Q' treatment resulted in inadequate preservative penetration. Air drying or high temperature drying followed by the Bethell process resulted in a high standard of treatment.
P Vinden, L Carter
Resin bleed after light organic solvent preservative treatment - the effect of drying method and process type
1986 - IRG/WP 3378
The effects of drying method and treatment process type on resin bleed were investigated. High-temperature drying of resinous radiata pine (Pinus radiata D. Don) heartwood resulted in improved wood permeability, higher preservative uptake, and greater resin bleed when treated by the Rueping process. Resin bleed was reduced substantially when timber was treated by the Lowry process, and totally eliminated when Bethell-treated. The incorporation of 2% wax into the preservative formulation may control resin bleed after Rueping treatment.
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
The effect of high temperature and long pressing time on the dimensional stability and decay resistance of OSB
2002 - IRG/WP 02-40237
The exterior use of OSB is restricted because when it is exposed to wet conditions swelling, loss of internal bond strength (IB) and decay occur. In this study an alternative process of pressing which results in the production of dimensionally stable and a more decay resistant strandboard was investigated. Boards were pressed at elevated temperatures for prolonged pressing cycles and their physical (thickness swelling and water absorption after 2 and 24 hours soak), mechanical properties (IB, MOR, MOE) and decay resistance were assessed. Analysis of variance (ANOVA, p=0.005) between pressing time/temperature and each property tested were used for the assessment of the results. The decay resistance of the boards was tested according to a draft European standard (DD ENV 12038: 1996) with a slight modification to the sample size. Boards were tested against Coniophora puteana, Postia placenta, Trametes versicolor and Pleurotus ostreatus. The results of this study showed that the increase of pressing time and temperature resulted in significant reductions in the thickness swelling and water absorption of the boards. The treatment had little effect on board mechanical properties. The resistance to fungal biodegradation was significantly improved at the higher temperature / pressing time combinations tested. The results of this study show that the production of a dimensionally stable and a more decay resistant OSB is possible without excessive use of preservative chemicals. If adopted these findings may lead to the development of new wood-based panel products (non-preserved dimensional stable and decay resistant hazard class 3-OSB) which may replace preservative treated plywood and solid wood for many exterior construction applications.
G J Goroyias, M D C Hale
Experiences from a Danish large scale test by means of a new method of treatment by attack of true dry rot fungus (Serpula lacrymans) in buildings
1994 - IRG/WP 94-10064
Experiences from a new and epoch-making method of treatment in connection with the repair of attack of the true dry rot fungus, Serpula lacrymans (Fr.) S.F. Gray, are described. The paper presents the background of a large scale test comprising repair of more than 150 Danish buildings over a period of approximate 5 years. The method being both gentle to the building and presenting savings of at least 70% compared with the traditionally known repairing methods is based on thorough recording of the extent of attack and examination of the vitality of the fungal attack combined with a changed chemical and constructive treatment including treatment by means of a newly developed heat treatment based on high frequency radio waves. Continuous controls have confirmed the applicability in practice of the method. Beyond the method, the paper discusses the consequences as regards security, possibilities of insurance and obtaining a mortgage loan.
O Munck, H Sundberg
Quality of timber impregnated with preservatives of class AB
after three years in service
2002 - IRG/WP 02-20241
Quality of impregnated timber is most often expressed by penetration and retention of the preservative used. Relatively less information is available about the performance of the final product, e.g. decks, panels etc. regarding product’s surface checks, deformations and overall appearance. Together with the timber durability, the above mention features are of esthetical importance in the above ground performance of timber. A comprehensive Nordic project dealing with pre-treatment, impregnation, durability and performance of Scots pine timber impregnated with copper-based preservatives for above ground use (class AB) was recently finished. The results from an above ground trail concerning the quality of timber are presented. The timber was dried in a conventional progressive, batch and high temperature kiln prior to impregnation. A significantly better quality regarding checks, deformations and deviation of the final moisture content, was achieved after conventional batch and high temperature dryings. Three preservatives (Kemwood ACQ 1900, Tanalith E and Wolmanit CX-8) were impregnated. The high temperature drying ensured the best penetration of all preservatives, but the retention was lower compared to conventional progressive and batch kiln dried timber. A part of the planks were conventionally kiln dried after the impregnation, the second part was air dried. Two decks with planks covering the variations in primary drying and preservative used were exposed; the former deck was in the open, the later one was under a shelter. After three years in service the planks were assessed regarding checks, deformations and moisture content. All three preservatives showed satisfactory appearance and no indication of decay was found. The deformations were comparable to those measured directly after final drying; the type of exposure had effect on the checks and moisture content of timber.
Effects of drying processes on termite feeding behaviour against Japanese larch wood
2001 - IRG/WP 01-10390
We investigated the effects of current drying schedules for larch lumbers on the termite feedings. Thermal analyses were also conducted to investigate degradation of wood components. Choice feeding tests showed specimens dried under high-temperature schedules were evidently susceptible against termite attacks. These schedules produced the feeding-attractants, which were suggested by the TGA results compared to the control samples. The results of this study indicated that the acceleration of termite feeding is taken place even under comparatively lower temperature than that of our previous researches.
S Doi, Y Kurimoto, H Takiuchi, M Aoyama
Wood kiln drying. Simple process of material treament or soft method of preservation? (Le séchage arificiel du bois. Simple opération de traitement du metériau ou méthode douce de préservation?)
1993 - IRG/WP 93-50001-14
Among the processes enabling to extend wood durability, kiln drying can be considered as a treatment and soft preservation method. Dry woods are naturally durable provided they are not subject to important retaking of the moisture. Drying thanks to the application of temperatures from 50 to120°C enable to execute a thermic treatment which kills grubs and mushrooms to ensure a sterilization that can be durable if wood doesn't retake water. Noumerous connections and analogies between drying process and the preservation one enable to conclude that kiln drying is a real operation of wood treatment either curative or to a smaller extent preventive.
Clean creosote - its development, and comparison with conventional high temperature creosote
1983 - IRG/WP 3235
Pigment emulsified creosote (PEC) is presently being tested and shows considerable stability in terms of water content, pigment level, pH, viscosity, rheological behaviour and microscopy. Timber samples from several eucalypt species have been treated with PEC and side matched samples treated with conventional high temperature creosote (HTC). The PEC treated specimens showed higher weight retentions of total preservative, (based on sapwood volume) than did the HTC treated samples. In terms of whole creosote however, retentions were not significantly different. Fuming was negligible immediately the PEC treated samples were removed from the pressure cylinder. In addition, the surface of freshly treated PEC samples was drier and much easier to handle than HTC treated samples and they remained dry even after eight months of weathering. 'Crud' formation on the surfaces of the exposed PEC samples was less than the corresponding HTC samples. There was no apparent difference in the penetration and macro-distribution of the two preservatives in the sapwood of matched samples. Full depth of sapwood penetration of both preservatives was visible.
C W Chin, J B Watkins, H Greaves
Comparison of the in-ground performance of pigment emulsified creosote (PEC) and high temperature creosote (HTC)
2000 - IRG/WP 00-30217
A long-term field trial was conducted in Australia to compare the in-ground performance of two oil-borne preservative formulations, conventional high temperature creosote (HTC) and a modified creosote formulation, pigment emulsified creosote (PEC). Three retentions (50, 100 and 200 kg/m³) were targeted for each formulation. An additional retention of PEC formulation (308 kg/m³), which contained 200 kg/m³ of creosote, was also included in the trial. Treated and untreated Eucalyptus regnans sapwood specimens were exposed horizontally below-ground to a range of economically important species of subterranean termites and wood decay fungi at two tropical and one semi-arid test sites. After 11 years of exposure, specimens treated with 200 kg/m3 of HTC and specimens treated with PEC containing 200 kg/m3 of creosote continue to perform well. Results of the field trial demonstrate that PEC will perform comparably to HTC on an equivalent creosote retention basis.
J W Creffield, H Greaves, N Chew, N K Nguyen
The loss of insecticidal action from synthetic pyrethroid-treated wood samples: The effect of high temperatures and relative humidities
1992 - IRG/WP 92-1569
This paper describes the results from bioassays using Hylotrupes bajulus, and chemical analyses, of pyrethroid-treated wood samples following storage for up to 3 years. A range of four storage environments was used consisting of combinations of two temperatures (20°C and 40°C) and two relative humidities (60% and 90%). It is concluded from the chemical analyses that, although losses at room temperature were small, at the higher temperature used in this study loss of insecticide was accelerated. Exposure of treated wood to high relative humidity did not appear to result in increased loss of insecticide. The bioassay results confirmed these conclusions. The significance of the bioassay results in relation to the long term efficay in service of preventive treatments is discussed and a logic proposed for deriving a service life on the basis of which an estimate of up to 58 years protection from current commercial formulations is derived.
R W Berry, S J Read
Termite durability of sugi (Cryptomeria japonica) heartwood kiln-dried under high-temperature process in relation to wood extractives
2005 - IRG/WP 05-10547
Termite durability of sugi heartwood samples kiln-dried under a high-temperature process were evaluated by using Reticulitermes speratus (Kolbe) as a test termite sp. The n-hexane extractives of these samples were analysed by a GC technique. The less termite durability was shown on the wood samples dried under the high-temperature process, in comparison with that of the air-dried samples. No GC-peak assigning to cubebol and epicubebol was shown in n-hexane extractives of kiln-dried samples.
S Shibutani, E Obataya, K Hanata, S Doi
Gaseous preservative treatment of wood
1990 - IRG/WP 3631
A recent development in processing wood with a gaseous preservative means that dry, treated wood can be produced in under 30 hours with the benefits of product diversification, faster stock turnover and the ability to respond to short term demand. About 400,000 m³ of wood are treated each year in New Zealand with boron salts to protect from borer infestation. Traditionally this treatment is effected by dipping the freshly sawn wood into a solution of boron salts and then stacking the wood while the salts diffuse through it. For 50 mm thick timber the diffusion process takes from 5 to 8 weeks. The Forest Research Institute has developed a new technique whereby the treatment is carried out in the gas phase effecting full impregnation within seconds. This process is carried out in a pressure vessel, which acts as both a kiln, preservation vessel and steam conditioning chamber. The wood is first high temperature dried to a low moisture content, exposed to a vapourised organoborate and then steamed. Total time in the vessel is about 30 hours. Preservative treatment in the gas phase is a novel development for the wood processing industry. An outline of the development of the process is presented and the implications for this industry are discussed.
R Burton, A J Bergervoet, K Nasheri, P Vinden, D R Page
Durability of Sugi (Cryptomeria japonica D.DoN ) wood treated in high temperature liquid paraffin
2002 - IRG/WP 02-40221
Sugi(Cryptomeria japonica D.DoN )wood was subject to a heat treatment in high-temperature liquid paraffin for the purpose of improving the resistance against fungi and termites without chemicals. The bath of paraffin liquid, which can provide a uniform heat transfer (±2?), was used at temperatures of 90?,120?and 150?.?ecay resistance according to JIS K 15711) was evaluated using a brown rot fungus(Fomitopsis palustris). Termite resistance according to JWPA standard 112) was conducted using a termite(Coptotermes formosanus Shiraki). Paraffin-treated wood had decay and termite resistance, however its effectiveness disappeared when the paraffin of wood surfaces was removed. The difference of durability didn’t depend on the treatment conditions of the temperature and time.
Y Matsuoka, W Ohmura, S Fujiwara, Y Kanagawa
High Temperature Treated Wood
2008 - IRG/WP 08-40429
High temperature can modify internal structure and physic-chemical properties of wood by a controlled pyrolysis process. Such treatment, among other changes in properties, modifies the wood color in a way that resembles exotic species, increasing its market value. The main objective of this work is to determine the changes in wood properties caused by the effect of temperature and time, in order to establish patterns of time for treatments performed at 220 °C through correlations based in heat transfer concepts. The high temperature treatment will be set at 220 °C during 20, 30 e 40 minutes in body tests of Pinus spp, using an electric wood dryer without steam, while the volume and mass of the wet wood, the dry wood (0%) and after the treatment ends will be controlled and measured. The results of alterations in color, hardness and dimensional stability of the wood and the data (with different temperature treatments) will be useful to set standards for high temperature treatments using theoretical concepts of heat transfer applied to the wood material, considering the wood properties variation, including cost effectiveness of wood products.
C C Borges, A L Barbosa, R Faber de Campos, S T Targas
Proposal for further work on accelerated ageing
1988 - IRG/WP 2314
Low temperature drying conditions of Pinus radiata wood for avoiding internal stain
1989 - IRG/WP 3507
It has been observed that, if in little sawmills, timber is dried with a low temperature schedule, it arrives at destination with internal sapstain besides of superficial mould. In this study, the lowest drying temperature at which wood should be exposed for sterilization, which results to be 52°C, is searched. It is not possible to avoid entrainment of pentachlorophenol, even though a waiting period of 72 hours after dipping the wood in a pentachlorophenate/borax solution before drying is considered. The residual content of pentachlorophenol in wood should be at least 400 µg/cm² or the moisture content less than 23% for avoiding the development of mould.
M C Rose
Problems caused by termites in buildings in the State of Sao Paulo
1976 - IRG/WP 150
Termites are the main insects attacking buildings in the State of Sao Paulo - Brazil. Their attack occurs in wood and wooden materials as well as paper, textile, leather and so on.
M S Cavalcante
Physical properties of ß-1,4-Xylanase produced by Postia (=Poria) placenta: Implications for the control of brown rot
1987 - IRG/WP 1318
The degradation of hemicelluloses is an early event in wood decay by brown-rot fungi. An understanding of the physical properties of hemicellulases may suggest target mechanisms for the development of new control agents. Endo-b-1,4-xylanase was partially purified by column chromatography from wood decayed by Postia (= Poria) placenta. The enzyme was extremely resistant to denaturing conditions; no loss of activity was detected after 2 h in 9 M urea or 6 M guanidine-HCl. Boiling the enzyme for 5 min in 2.5% SDS + 0.5% b-mercaptoethanol reduced its activity by 65%, as measured by the production of reducing sugars. The activity of a-D-galactosidase, another enzyme detected in large quantities in the decayed wood, was reduced by 98% under these conditions. Optimum pH and temperature ranges were pH 2-6 and 50-60°C, respectively. The enzyme appears to be a glycoprotein containing 50-60% carbohydrate (w/w); the carbohydrate moiety may protect the enzyme from adverse environmental conditions. The control of brown rot by in situ inactivation of xylanase may not be feasible because of the enzyme's extreme stability.
J A Micales, F Green III, C A Clausen, T L Highley
Detection of feeding behaviour of termites using AE monitoring
1991 - IRG/WP 1514
Using acoustic emission (AE) monitoring, the feeding activity of the termite inhabiting a wood specimen was investigated. The amplitude and the rate of AE from the specimen of Coptotermes formosanus Shiraki was larger than that of Reticulitermes speratus Kolbe. The AE event rate was higher in the specimen with soldiers than without soldiers. The AE event rate decreased according to the resistance of wood specimens against termite attack.
Y Imamura, M Tokoro, M Owada, Y Fujii, M Noguchi
Studies on accelerated ageing procedures with TBTO-treated wood
1985 - IRG/WP 2244
The efficacy of various procedures for accelerated ageing of organotin based wood preservatives in treated wood has been investigated. It was found that leaching of the treated wood samples in water according to the European Standard EN 84 was not satisfactory for organotin based preservatives and is probably also unsuitable even for other types of organic solvent preservatives. Keeping tributyltin oxide (TBTO) treated samples in a heating cabinet at 70°C for five weeks, however, had a considerable effect on the breakdown of TBTO and the subsequent decay test. Therefore, an ageing procedure involving a heating period should be considered for all organic solvent wood preservatives. The investigation also confirmed that elevated temperatures accelerate the degradation of TBTO and that there is a strong correlation between the percentage of TBTO in the wood and its resistance against decay.
J Jermer, M-L Edlund, B Henningsson, W Hintze
Improved equipment and technique for high pressure sap displacement impregnation of natural round wood
1972 - IRG/WP 309
Hitherto the main problem in the practical application of high pressure sap displacement impregnation (HPSD) has been in devising a satisfactory cap. Such a cap must be easily fitted to different size log ends to give a leak proof seal. The present contribution describes a new type of cap and sealing system designed to meet these requirements.
C G W Mason, F B Shorland
The most important characteristics of some species of the genus Hypoxylon found in Serbia, Yugoslavia
1977 - IRG/WP 165
Studies on the destruction by marine borers of fishing boats along the north-eastern Black Sea coasts of Turkey
1980 - IRG/WP 451
Marine wood-boring organisms are attacking fishing boats along the northeastern coasts of the Black Sea, Turkey. The damage and the intensity of attack of Teredo navalis L in fishing boats were studied.
O A Sekendiz, R Ilhan