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Effect of wood polymers degradation during heat treatment on extracellular enzymatic activities involved in beech degradation by Trametes versicolor
2008 - IRG/WP 08-40392
Effect of heat treatment on extracellular enzymes involved in wood degradation by Trametes versicolor was investigated. Heat-treated and untreated beech blocks were exposed to T. versicolor on malt agar medium and extracellular enzymatic activities investigated. A strong ABTS oxidizing activity has been detected during the first stage of colonization in both cases, while cellulase activities are mainly detected in the case of untreated beech wood. Further investigations carried out on holocellulose, isolated using sodium chlorite delignification procedure, either on untreated beech wood or heat treated one, indicate that commercially available cellulases are able to hydrolyse totally holocellulose from untreated sawdust, while hollocellulose from heat treated one was only partially hydrolysed. CP/MAS 13C NMR analysis of heat treated beech wood but also its lignin and holocellulose fractions obtained after acidic hydrolysis of polysaccharides or delignification with sodium chlorite indicates an important modification of hollocellulose showing degradation of hemicelluloses as generally described in the literature, but also formation of carbonaceous materials within the wood structure. All these data suggest that chemical modifications of wood components during heat treatment disturb enzymatic system involved in wood degradation.
S Lekounougou, G Nguila Inari, M Pétrissans, S Dumarçay, J P Jacquot, E Gelhaye, P Gérardin


A novel enzymatic treatment as a new approach for wood protection
2015 - IRG/WP 15-40701
Wood durability is a worldwide concern and most treatments tend to fail with regard to their efficacy along the time. Weather conditions lead to a loss of the treatment substances into the surrounding environment and, in consequence, generate also a public health concern. Recently, the employment of oxidative enzymes, such as laccases, has been proposed as a tool for lignocellulosics modification in order to change wood surface by anchoring compounds that confer new properties to wood. Among the advantages of this strategy, it can be highlighted the fact of the formation of covalent bonds between the wood and the compounds of interest. Consequently, future leaching of the linked substances is expected to be avoided and treatments could be long-lasting and safer for the environment. Therefore, enzymatic grafting appears to be a promising methodology for the modification of chemical wood composition and properties. In this work, a grafting strategy is proposed for providing resistance against wood decay fungi to wood. For this purpose, experimental conditions of the grafting were studied regarding time of reaction, enzyme dose, substrate dose, temperature and operational mode. Kraft lignin was used as a phenolic substrate to model the grafting due to its biocidal properties and to the fact that grafting degree could be determined indirectly by means of colorimetric measurements. In addition, it represents a residue of the paper industry, so, this strategy allows also the exploitation of a waste. Time of reaction has appeared to be the main factor when the grafting is carried out in aqueous solution. However, in this study it has been proved that the best results of the grafting are achieved when the reaction occurs out of the aqueous medium. Washing with hot water of the treated wood veneers was also performed, to remove substrates not attached, and has revealed a good linkage of the lignin onto wood. Finally, preliminary durability assays with Coniophora puteana were carried out and have shown good prospective applications for this type of wood treatments.
C Fernández-Costas, S Palanti, M Ángeles Sanromán, D Moldes


Wood properties modification by an enzymatic assisted treatment with phenolic extractives
2016 - IRG/WP 16-30696
Extractives of sawdust and bark from P. pinaster and, condensed tannins (CTs) from P. radiata bark were used to treat beech and pine veneers in combination with an oxidative enzyme, in order to stably graft such extractives onto the veneers. First, the antifungal activity of P. pinaster phenolic extractives against wood decay fungi was studied. These extractives were also used to hydrophobize pine and beech wood by means of the treatment with laccase enzyme. The same treatment was performed with CTs from P. radiata and chemically derivatized CTs (HPTs) to modify the physiochemical properties of beech wood. Sawdust extractives of P. pinaster showed a high growth inhibition of P. ostreatus and C. puteana. Besides the biological activity, the treatment with laccase and the mentioned phenolic extractives provided stable hydrophobic properties to pine and beech wood. The chemical derivatization of CTs enhanced the hydrophobic properties of native CTs. After the inclusion of such HPTs in the enzymatic treatment of wood veneers, a higher resistance to water absorption was obtained. Thus, the stable graft of P.pinaster phenolic extractives onto wood provided biological and hydrophobic properties. The chemical derivatization of natural phenolic extractives improved their chemical and biological properties which opens a new perspective for future applications of these compounds.
D Filgueira, C Fernández-Costas, D E García, D Moldes


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


Proposal for further work on accelerated ageing
1988 - IRG/WP 2314
M-L Edlund


Status of the research and development of a new preservative system (EFPL) for pressure treatment of spruce in Canada
1975 - IRG/WP 348
Our work has been to develop a system which would have the stability of the ACA system and the formulation flexibility of the CCA system enabling properties such as fixation of arsenic, water repellency, appearance and cost to be controlled. Our permeability studies of spruce using a method previously developed indicated that an ammoniacal solution of copper arsenate is an excellent candidate for the treatment of spruce. Studies of the permeability of spruce sapwood microsections to CCA preservative and to an ammoniacal solution of copper arsenate proved that the ammoniacal system penetrates 1.7 to 1.8 times faster than the CCA system, in the radial direction. The permeability in the tangential direction was on the average 3.8 times better. These results were confirmed by pressure treatments of spruce lumber and spruce roundwood with both preservatives.
J Rak, M R Clarke


IRG/COIPM INTERNATIONAL MARINE TEST - to determine the effect of timber substrate on the effectiveness of water-borne salt preservatives in sea-water. Progress Report 2: Report of treatment and installation in Australia
1978 - IRG/WP 440
The purpose of this test and the procedures to be followed have been fully set out in documents distributed by the International Research Group on Wood Preservation and numbered IRG/WP/414 and IRG/WP/420. The prescriptions set out in these two documents have been closely followed.
J Beesley


Field test evaluation of preservatives and treatment methods for fence posts
1985 - IRG/WP 3347
This work presents the field test results after fifteen years exposure of Eucalyptus saligna fence posts treated with six different preservatives and five treatment methods. All the combinations with oil-borne preservatives presented the best results and among the waterborne preservatives, the fence posts treated by immersion method were with the lowest performance in the field test.
G A C Lopez, E S Lepage


Manual of a mini treating plant for waterborne preservative treatment of timber and bamboo
1999 - IRG/WP 99-40130
This contributional article includes machinaries and equipments necessary for a small wood treating plant for the pressure treatment of tim bers with waterborne preservatives along with the cost and design. The preservative treatment limitations, treatment schedules and specifications for different products have been described. The cost of a mini treating plant will be 6,00,000 Tk. (13,000 US$), suitable for preserving timber and bamboo products for indoor and outdoor uses and will out last teak wood. The additional durability of timber and bamboo will create economically and environmentally safe conditions.
A K Lahiry


How to Document the Performance of Super-Critical Treated Wood in above Ground Situations?
2005 - IRG/WP 05-20316
The paper presents practical experiences from the preparation of a new preservative treated wood product for introduction to the market. The product in question is Superwood™, which is treated with organic biocides using CO2 in a supercritical state as a solvent. The question is how to evaluate the performance of a new product such as Superwood™ in order to get an acceptance on the market and fulfil the formal requirements. In the European Union countries, the EN 599-1 is the standard that needs to be complied when approving a new product for the market, but it only focuses on the toxic limit against representative decay fungi according to EN 113. However, decay test, above ground and other forms of field tests are optional, this is not in line with the traditional test philosophy in the Scandinavian countries. The open question is to which extent treatment to the level of the toxic threshold value also ensures a long service life and expected performance of the treated commodity. Superwood™ is evaluated using a strategy, in which basic laboratory tests are done to get the toxic value (according to EN 599-1) and in addition a number of field tests are done including accelerated testing in the tropics. These tests are focussed on the evaluation of the performance criteria such as durability and service life and maintenance requirements. These questions must be answered by the producer without having a full record of performance test for their new products. A short status on the test performed on super-critical treated wood (Superwood™) is presented. Based on a comparison between field test in Scandinavia and in the tropical Malaysia a service life of more than 25 years for a specific supercritical treated product is estimated. It is stated that the existing European standardisation system is insufficient when it comes to service life prediction. A number of important questions need to be addressed by the European standardisation system as soon as possible because the market and the public opinion change quickly due to environmental concern.
N Morsing, A H H Wong, F Imsgard, O Henriksen


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


The dry rot fungus Serpula lacrymans. Examples of attack and remedial treatment
1988 - IRG/WP 1347
The film deals with several aspects of dry rot attack and eradication in buildings. The detailed biology and morphological charasteristics of the fungus are portrayed. The various forms of mycelial growth, the role of the strands in the nourishment and spread of the fungus, as well as the many types of fruitbody formation are outlined. Environmental and nutritional requirements of the fungus as well as the potential infection danger posed by the basidiospores are discussed. The second part of the film, outlining the main reasons for dry-rot attack and spread in building together with the significant damage caused, shows the full extent of the problem to expert and lay-person alike. The necessity of correct survey and inspection of decayed areas to determine the full range of attack is stressed. Examples of various remedial treatments and the present technological state of eradication techniques, e.g. pressure injection, in Germany are discussed.
G Buchwald, B M Hegarty, W Metzner, R Pospischil, H Siegmund, P Grabow


Soft rot penetration - Effect of groundline maintenance treatment on poles in sevice
1983 - IRG/WP 3263
R S Johnstone


Improved techniques designed for evaluation of fungicides in soil for control of dry rot fungus Serpula lacrymans
1985 - IRG/WP 2238
Improved techniques provide a laboratory method for the evaluation of chemicals in soil for control of dry rot fungus Serpula lacrymans. Results with their application to three chemicals were reported. These techniques are useful to eliminate chemicals lacking the necessary toxicity and weatherbility for dry rot control when the chemicals have been applied to the soil.
M Takahashi, K Nishimoto


Natural durability transfer from sawmill residues of white cypress (Callitris glaucophylla). - Part 3: Full penetration of the refractory sapwood of white cypress
2000 - IRG/WP 00-40167
The heartwood of white cypress, Callitris glaucophylla, is renowned for its termite resistance and durability against decay. The sapwood, which can represent up to 30% of log volume, is non-durable and refractory to conventional preservative treatment. Previous work ascribes the lack of permeability to oily deposits within tracheids and ray cells. Environmental scanning electron microscopy was used to investigate ultrastructural aspects of sapwood permeability. Several pre-treatment processes to improve permeability were tested with limited success. Solvent drying allowed preservative penetration but damaged the structure of the timber. Neither, long term water soaking nor an oscillating pressure/vacuum cycle had any effect on porosity to water-borne treatments. Through extensive modifications to a standard VPI process we can now repeatedly achieve full penetration with organic solvent-based wood preservative solutions into white cypress sapwood. Effects of this process on the strength of the timber are being evaluated. Work is continuing as to the most effective and efficient treatment schedule and the latest results will be presented at IRG 31.
M J Kennedy, L M Stephens, M A Powell


Problem of the treatment of dried sawn spruce building timbers with water-borne preservatives. Interim reports for discussion at the 4th Annual Meeting in West Berlin on 27 October 1972
1972 - IRG/WP 311
One of the most difficult technical problems facing the preservation industry is how to improve the treatment of refractory species of timber such as spruce. Its resistance to penetration, even under pressure' precludes its use for more hazardous service situations, and even in less severe conditions a higher level of treatment would be desirable. The importance of this subject led us to look once again at possible ways of improving treatment.
W Liese, J W W Morgan, T Hof, R O Ullevålseter


Thermal treatment of wood: European Processes and their background
2002 - IRG/WP 02-40241
Recent efforts on thermal treatment of wood lead to the development of several processes introduced to the European market during the last few years. The total production capacity of heat treated wood in 2001 is estimated as approx. 165.000 m3. In the paper the different heat processes are presented. The general technology as well as scientific data on the chemical transformation of the cell wall polymers, on the biological performance, on the physical and mechanical properties of the treated wood are presented and discussed
H Militz


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


Treatment of fresh green round bamboos culms (Dendrocalamus strictus) by sap-displacement (wick) method
2005 - IRG/WP 05-40311
Sap displacement method has great potential for treating short length bamboos as it does not require any technical equipment. The process is simple and large nos. of bamboos can be simultaneously treated in relatively short period. There is no wastage of chemicals as the remnant solution reused. Bottom ends and middle portion had better treatment in compared to lop end portion. With increasing length of the flow of preservatives is impaired. The method culms can conveniently 3m length.
R Lal, C N Vani


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


Water-based wood preservatives for curative treatement of insect-infested spruce constructions
1998 - IRG/WP 98-30171
On laying down sanitation measures for wooden constructions infested by wood boring insects, we must take into account static risks for the construction - and, thus, for the security of the user - as well as risks for humans and environment due to the chemical preservative compounds of the treated wood. Analyses on many roof constructions made with spruce (Picea abies L.) have revealed that Hylotrupes bajulus L. and Anobium punctatum De Geer have not the significance given to them for decennies. That often allows to replace solvant-based with water-based wood preservatives in old buildings, for the protection of humans and environment. Therefore, a method has been developed in Switzerland for testing wood preservatives with delayed curative efficacy against the house longhorn beetle. Like the European Anobium Standard EN 370 this method intends to prevent the emergence of Hylotrupes beetles. Laboratory tests with diverse water-based wood preservatives available on the market in Switzerland have shown that particularly boron and benzoylphenylurea derivatives containing products get a sufficient penetration in the wood and prevent the emergence of the beetles.
E Graf, P Manser, B Lanz


Preservative treatment of Eucalyptus saligna fence posts by the double-diffusion method
1982 - IRG/WP 3196
Eucalyptus saligna fence posts treated by the double-diffusion method with two chemical combinations showed average lives of 11.2 years (copper sulphate and potassium dichromate at 10.5 kg/m³ retention)and of 14.3 years (copper sulphate and sodium mono-H arsenate at 7.1 kg/m³ retention), as determined in five test sites in the State of Sao Paulo, Brazil. The exponential model was the best fit when expressing average life by the Decay Index (DI) as a function of time.
E S Lepage, A R De Freitas


Options for accelerated boron treatment: A practical review of alternatives
1985 - IRG/WP 3329
Boron wood preservatives are almost exclusively applied by momentary immersion and block diffusion storage. Alternative techniques are described which can be used to accelerate boron treatment. Diffusion coefficients have been derived to define the acceleration of diffusion with increasing temperature. Schedules are described for pressure impregnation of green timber, involving steam conditioning, evacuation and alternating pressure method treatment. Timber Preservation Authority penetration and retention requirements can be met in approximately 4-5 h. The optimum schedule, however, included a 12 hour holding period between steaming and preservative treatment. A method of applying boron preservatives as a vapour is described, Trimethyl borate vapour reacts with wood moisture to form boric acid. The kinetics of this reaction, however, are very fast. This limits treatment to timber dried to very low wood moisture contents.
P Vinden, T Fenton, K Nasheri


An investigation of the effects of pre-steaming on the treatment of sawn spruce timber with Celcure A, a copper-chrome-arsenic preservative
1981 - IRG/WP 3150
Difficulties in the treatment of spruce using standard vacuum/pressure techniques with both water-borne and organic solvent preservatives are well known. We have evaluated the influence of steaming on treatability with a waterborne CCA preservative.
C R Coggins


The utilisation and preservation of Eucalyptus globulus agricultural stakes from Portugal
1989 - IRG/WP 3520
This paper reviews the development and utilisation of Tanalith C treated Eucalyptus globulus stakes: particular reference is made to their use in vineyards. The treatment characteristics of commercially available stakes will be described and penetration patterns evaluated.
A Milne e Carmo, D A Lewis, A Lyman


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