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Microwave conditioning of Pinus radiata D. Don for preservative treatment
2000 - IRG/WP 00-40182
This paper reviews the effect of pressure steam conditioning on the permeability and treatability of green radiata pine heartwood and the potential for substituting microwave conditioning for steaming. The penetration of liquids into radiata pine occurs mainly in the radial tissue. The permeability of green radiata pine improves following steam conditioning by blowing out the soft radial tissue. The moisture content of the wood is also reduced following steam conditioning thus increasing the air void volume available for liquid penetration. Intensive microwave irradiation is found to improve the permeability of radiata pine and reduce wood moisture content concurrently thus facilitating immediate impregnation with wood preservatives.
P Vinden, G Torgovnikov, J Romero


Effects of pretreatments for the amelioration of preservative impregnability using the Oscillating pressure method (OPM)
1995 - IRG/WP 95-40044
For the purpose of an amelioration of preservative impregnability, three types of pretreatment: the steaming, the explosion and the boiling, were tested. The specimens were prepared by the domestic four species: Itajii, Ryukyumatsu, Sugi and Hinoki, and 1 refractry imported species: Douglas-fir. The dimension of specimens was 20 x 20 x 300 mm³ and were treated with CCA in a laboratory OPM machine. Three OPM schedules and Bethel process without after vacuume were tested in this experiment. The results obtained were follows: 1. In the case of the treatment of green woods, the calculated retentions of preservatives based on those initial mass, were periodically slowly increased or sometimes decreased. This reason was considered the replacement of the free water in wood to the preservative solution. The sapwood of rather easy treatable species like Ryukyumatsu, was obtained good penetration by Bethel process. The sapwoods of treatable species like Sugi and Hinoki, were obtained best penetration by OPM-1 or by OPM-2. The combination of the steaming and the OPM was rather good results for all species tested of green woods. 2. In the case of the treatment of the air-dried woods, the combination of the steaming and the OPM was obtained rather good results for all species tested included the refractry specimens like Douglas-fir.
K Suzuki, I Asaoka, S Tani, K Okada, T Hidaka


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.
P Vinden


Dynamics of pressure changes in wood during impregnation
1990 - IRG/WP 3615
Conventional methods of impregnation have to be improved for achieving better penetration of refractory wood species. Basic requirements for an adjustment of treatment schedules are, amoung others, a profound knowledge of the course of pressure changes in the wood during treatment. A new method of pressure measurement was developed which supplies exact and reproducible data. The results show that air pressure spreads more rapidly in wood than water pressure. In pine, water pressure is built up in radial direction within hours an declines slowly after pressure release. In spruce, air and water pressure spread more rapidly in green wood than in dry wood. Water pressure of 5 bar applied in radial direction is not achieved within 8 hours time. 5 minutes successions of pressure and pressure release have no effects at 10 mm depth. These findings call into question the conventional OPM technique of rapid successions of pressure and vacuum, and possibly allow easier treating techniques.
R D Peek, S Goetsch


A method for the preliminary assessment of timbers for their treatability with preservatives under pressure
1977 - IRG/WP 3100
President Maurice Fougerousse has provided the following references to a IUFRO report, published in English, French and German, which may be of interest to IRG members: 'A method for the preliminary assessment of timbers for their treatability with preservatives under pressure', PANS Vol 23, No 2, 153 158, June 1977. 'Une methode d'evaluation preliminaire de l'aptitude a l'imprignation sous pression des bois avec les produits de preservation'. 'Un metodo de apreciacion preliminar de la aptitud para la impregnacion por presion de las maderas con productos de proteccion', Bois et Forets des Tropiques, No 166, 48 54, Mars-Avril, 1976. 'Ein Verfahren zur vorläufigen Beurteilung der Tränkbarkeit von Holzarten mit Schutzmitteln unter Druckenanwendung', Material und Organismen, 10, (4) 311 318, 1975. Please note that the IRG Secretariat regretfully has no reprints of these papers for distribution.
M Fougerousse


Possibilities of improving the oscillating pressure method
1991 - IRG/WP 3668
Studies on the dynamics of pressure changes in wood during impregnation revealed no significant effect of fast pressure changes for green spruce as used by OPM (IRG/WP/3615). The following experiments were carried out on several hundreds of spruce palisades to examine the modification of single procedure parameters of common use OPM and to record the effects on the impregnation result with the aim of simplifying the energy and cost expensive technique, retaining the same or possibly an improved treatment quality. The samples were endsealed and impregnated with CCB (4%), their actual effective substances being defined by AAS at the beginning and at the end of the treatment. Generally, programme variants with several pressure changes, independent of their number, duration and dynamics, resulted in a better penetration of the sapwood than programmes where a constant pressure was used. Fast pressure alternation within a few seconds did not result in a noticeable better impregnation quality. A dynamic change of the phase lengths and of the distribution quotient for pressure and vacuum respectively atmospheric pressure did not improve the treatment result. Sapwood moisture content between 100 and 180% are optimal preconditions for a good treatment quality.
S Goetsch, R-D Peek


A non-pressure method of protection based on hurdle theory to control the spectrum of internal environmental factors which affect the decay of poles in soil contact
1993 - IRG/WP 93-20005
A field trial was conducted to establish whether superficial barrier linings on poles in soil contact could function as environmental hurdles against the growth of biological agents and thus provide preventative methodology to preclude premature failure of vineyard poles under flood-irrigation. Assessment after 52 weeks exposure to the prevailing conditions and sub-tropical environment showed that open-ended cylindrical linings of biologically inert heat-shrink polyethylene applied to the vertical soil-contact surfaces of Eucalyptus grandis poles unequivocally prevented termite-induced failure of untreated poles, basidiomycete decay of creosote-treated poles and fungal colonisation of CCA-treated poles. The success of the liners in prevention of incipient decay of these poles was explainable on the basis of hurdle theory and was therefore attributed to the ability of the former to control essential growth factors and create internal conditions inimical to the proliferation of decay agents in the poles. Consequently, sub-optimal conditions of Aw, Eh, and nitrogen content were considered to have arisen to function as environmental hurdles which decay agents could not overcome at wood-soil interfaces.
A A W Baecker


Protection of rubberwood timber. Part 1: Impregnation with boron preservatives
1989 - IRG/WP 3551
Rubberwood (Hevea brasiliensis) were treated with a 3% proprietary mixture of borax/boric acid using three different treatment schedules i.e. full-cell, full-cell to refusal and full-cell with 12 cycles of vacuum/pressure. Freshly cut samples had mean preservative retentions of 187 kg/m³, 214 kg/m³ and 178 kg/m³ respectively. Pre-air dried samples for one week had retentions of 252 kg/m³, 308 kg/m³ and 282 kg/m³ respectively. An increase of pressure time from 45 minutes to 90 minutes allowed for slightly higher retention values. Preservative retentions of the core (20 mm² around the centre) from freshly sawn samples were 0.08-0.13% m/m BAE (boric acid equivalent), 0.04-0.19% m/m BAE and 0.04-0.21% m/m BAE for the full-cell, full-cell to refusal and full-cell with 12 cycles vacuum/pressure treatment respectively. Retention values of similar samples from the surface up to a depth of 10 mm were 0.36-1.51% m/m BAE for the 3 different treatments.
L T Hong, C C K Liew


Wood furfurylation process development. Part 1: Oscillating Pressure Method
2007 - IRG/WP 07-40376
Furfurylated wood (wood modified by furfuryl alcohol) has over the last years gained marked shares from both tropical wood and conventional preservative treated wood and this has, in turn, generated several research projects concerning process development. The impregnation of spruce is well known from literature to be a difficult task. Furthermore, the sapwood of Scandinavian-grown Scots pine is also known to be difficult to fully impregnate from time to time. The primary objective of the study was to evaluate whether the Oscillating Pressure Method (OPM) could be used to impregnate green and dry Norway spruce wood (Picea abies) with a Furfuryl alcohol (FA) - mixture. The secondary objective of the study was to evaluate if OPM could improve the penetration of FA in Scots pine (Pinus sylvestris) as compared to conventional full cell (Bethell) treatment. Impregnation tests were carried out on boards and planks as well as 300 mm and 500 mm clear wood samples. Samples were removed for MC measurement and the initial weight of the test samples was determined. Four different impregnation schemes were tested. The results indicate that Norway spruce can be impregnated by the OPM method to produce a protective shell of treated wood around a core of untreated wood. The penetration in Spruce showed great variation between different boards and between different parts of the individual boards. This is in part expected, but can also be caused by uncontrolled pre drying of the test material which was stacked uncovered after sawing. For Scots pine, the OPM improved the penetration of both sapwood and, to some extent, the outer heartwood.
E Larnøy, M Westin, B Källander, S Lande


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.
I Usta


Preliminary investigation for preservation method of CLT using non-pressure treatment
2021 - IRG/WP 21-40919
Cross-laminated Timber (CLT) is increasingly being used in residential and non-residential construction around the world, and some of these areas are at high risk of biodeterioration. Addition to moisture management of construction, preservative treatment of CLT may be needed to prevent decay and termite attack in the area. Pressure treatment being most reliable, is not feasible due to the large dimensions of CLT panel. Also, fabrication of CLT using pressure treated laminas has some difficulties about re-drying cost and physical damages such as distortion and delamination. Non-pressure treatment called “deep penetration treatment” has increased their share on treated wooden sill prate (Dodai) in Japan. The treatment consists of incising with specially designed blades and spraying with the solvent-based wood preservative. In the present investigation, we tried to apply this treatment to CLT panel. Laboratory scale test and full-scale test were carried out using 5-layer CLT panel with 150 mm thickness, 500 mm width and 800 mm length, and 150 mm thickness, 900 mm width and 3400 mm length, respectively. In the laboratory test, average penetration by the dip treatment was 98% in the 10 mm depth zone of central part of specimens, although wood preservative hardly penetrated into the inner layers. In the full-scale test, the penetration from wide face to 10 mm depth was 93% by the dip treatment and 90% by the surface treatment in the central part of the CLT. Penetration from the narrow face of the CLT was very low, probably due to the lack of incising. Although further evaluation and improvement are required for practical use, but the deep penetration treatment is expected to become one of the CLT preservation treatment methods.
T Miyauchi, Y Ohashi, J Miyazaki, R Takanashi, H Shibui, S Isaji, T Shigeyama, Y Sugai, A Yamamoto, T Hramiishi, T Mori, H Matsunaga


Danish wood preservatives approval system with special focus on assessment of the environmental risks associated with industrial wood preservatives
2001 - IRG/WP 01-50166-01
The following is a description of the procedure used by the Danish Environmental Protection Agency to assess the environmental risks associated with preservatives used in the pressure impregnation of wood. The risk assessment covers issues considered to be of significance for the environment and which are adequately documented so as to allow an assessment. Such issues are persistence and mobility in soils, bioaccumulation and the impact on aquatic and terrestrial organisms. Unless required in special circumstances, the assessment does not apply to birds and mammals as the normal use of preservative treated wood is not expected to involve any noteworthy exposure of these groups. Approval of wood preservatives will be based on a general assessment of the environmental risk associated with the normal use of wood treated with the preservative in a realistic worst case situation. The assessment may address other aspects such as disposal and total life cycle.
J Larsen


Proposed method for out-of-ground contact trials of exterior joinery protection systems
1981 - IRG/WP 2157
Methods for testing the efficacy of preservative treatments for exterior joinery are described using the format of a European Standard. Commercially used treatments applied to jointed test units (L-joints) which are then protected by conventional finishes are exposed to normal outdoor hazards out of ground contact. Assessment is made a) by determining eventual failure through decay and b) by destructive examination of replicate treated and untreated units, after increasing time intervals, rating comparative performance in terms of wood permeability increase and the progress of microbial colonisation.
J K Carey, D F Purslow, J G Savory


JWPA method for testing effectiveness of surface coatings with preservatives against decay fungi
1981 - IRG/WP 2164
In 1979 JWPA established a new method for testing effectiveness of surface coatings in accordance with practical use of preservative-treated lumber. Comparing the new testing method with JIS A 9302, a few new trials - size of wood specimen, weathering procedure, and decay-test procedure - are incorporated.
K Tsunoda


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


A suggested method to test the toxicity of wood preservatives towards the house longhorn beetle
1977 - IRG/WP 275
This method was developed in the Institute for Wood Technology in Sarajevo, Yugoslavia and is used to get quick information on the toxicity of wood preservatives against house longhorn beetle (Hylotrupes bajulus). The method can be used for superficially treated or deeply impregnated wood blocks, and by using small or normal size test material it can be used as a laboratory or field test, and also for accelerated infestation of test material out of ground contact. The paper is given to the International Research Group on Wood Preservation as a suggested method which could possibly be used as a standard. Only the laboratory test method is described.
N Vidovic


Testing of wood preservatives against marine borers (Part 1). Method of testing wood preservatives against marine borers (Part 2)
1971 - IRG/WP 37
P C Trussell, C C Walden


The use of pressure cycling to improve heartwood penetration in Pinus radiata (D. Don)
1995 - IRG/WP 95-40050
This study investigates the effect of cycling pressure on the treatability of radiata pine heartwood. The results indicate that liquid penetration into the heartwood is affected by the preconditioning method used and pressure treatment time. There is no significant improvement in the penetration of Pinus radiata (D. Don) heartwood when a cycling or pulsation process is used.
P R S Cobham, P Vinden


Collaborative soft rot tests: PRL tests of Cu/Cr/As preservative using method of Document No: IRG/WP/208
1973 - IRG/WP 223
These tests were undertaken as a preliminary to the next series of collaborative soft rot tests. An interim report has already been presented at Berlin in 1972 as Document No: IRG/WP/211
J K Carey, J G Savory


Non-pressure treatability of plywood by CCA, CCB and boron
2005 - IRG/WP 05-40295
Study on diffusibility and absorbability of CCA, CCB and boric acid in 3 mm thick 3-ply hardwood plywood at water saturated and air-dry conditions and dipped at same concentration (5%) and same duration of time (12 hours) revealed complete diffusion of all the preservatives at water saturated condition. Only the CCA-C was found absorbed by the plywood at air-dry condition. The rate of absorption and diffusion of CCA-C was found about 4.5 times higher than CCB and boric acid.
A K Lahiry


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


An evaluation method for less termite attack execution on thermal insulation for fundation walls
2002 - IRG/WP 02-20245
According to the results by the real scale Japanese building tests, the termite installation was observed at very little spaces between foundation and insulation. The termite penetration spaces between foundation and insulation on foundation systems in Japanese wooden houses were checked by the way of streaming speed of colored water. Because of difficulty for its execution, the parts of outside angles and reentrant angles in continuous foundation were more sensitive for the termite penetration. Special accessories of thermal insulation for these angles can be effective for lesser termite installation.
K Suzuki, Y Tanaka


A practical method to evaluate the dimensional stability of wood and wood products
1990 - IRG/WP 2342
This paper presents a new simple method to evaluate wood and wood products for their resistance to swelling and to assess wood preservatives for their ability to dimensionally stabilize treated wood exposed to water. Permeable wood of various dimensions and treated with different preserving chemicals have been measured for swelling in the radial and tangential direction during immersion in liquid water. The results indicate that a simple exponential function describing the dimension of the samples during immersion can be used to evaluate both the water-repellency and anti-swelling effectiveness of wood preserving chemicals. The results can be achieved in reasonable time, and the parameters of the function can be determined by a commercial desk-top computer program.
J P Hösli


CEN Draft (38 N 460E) Standard: Test method for determining the protective effectiveness of a preservative in the marine environment
1986 - IRG/WP 4132
This European Standard describes a marine test method which provides a basis for asseasing the effectiveness of a wood preservative used to prevent attack of timber in sea-water by marine borers. The method is only suitable for testing preservatives which are intended to prevent attack by marine wood boring organisms of treated timber for use in more or less permanent contact with sea-water. It is not suitable for assessing the effectiveness of preservatives against micro-organisms. The main objective of the method described is to evaluate the relative effectiveness of a wood preservative applied by vacuum/pressure impregnation. For this reason permeable timbers are used throughout so that the protective efficacy of various retentions of the preservative can be determined. However, it is recognized that modifications of the method may be used for other purposes, e.g. to determine the relative efficacy of a preservative treatment or to determine the natural durability of the heartwood and sapwood of a selected timber species. The method is primarily intended for testing in temperate waters where Teredine and Limnoria borers dominate. However, it is also capable of being used in tropics where attack by Pholads and specific Crustacean borers may be very destructive. It has to be considered that the test has to be run for a minimum period (usually for 5 years or until the point of failure) before any interpretation of the results can be made. Variations in the test conditions can be expected from one test site to another depending on temperature, salinity, population density of the various borer species etc. This will inevitably influence the general rate of attack. However, by comparing the results obtained for samples treated with the test product with those obtained with a reference preservative and those obtained with untreated control samples, the relative protective effectiveness of the product tested can be evaluated.
G Castan


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


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