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Preservatives treatment and field test monitoring of spruce pole stock: CCA and fumigant treatments
1990 - IRG/WP 3619
The fumigants trichloronitromethane (chloropicrin) and sodium N-methyldithiocarbamate (SNMDC) were used to treat red spruce pole stock, either CCA treated or untreated, through holes bored through the pole's center. The poles were analyzed for the presence of microorganisms immediately before ground installation and again after installation at a pole test site. Monitoring of fumigant movement in the poles was also performed after one year. Results indicate that both fumigants moved throughout the ground line regions of the poles, although less toxicity to the bioassay fungus was observed in the SNMDC treated poles. Reduced fumigant levels, and more sporadic diffusion was noted in the above ground portions of both chloropicrin and SNMDC treated poles although again chloropicrin exhibited greater toxicity to the bioassay fungus. Despite the variability of fumigant diffusion as determined by bioassay, no decay fungi could be isolated from the treated poles after one year. This was in contrast to high frequency isolation of decay from control poles.
A J Pendlebury, B Goodell

Fumigant movement in Canadian wood species
1984 - IRG/WP 3296
Pole sections prepared from seven Canadian wood species (Thuja plicata, Thuja occidentalis, Pinus contorta, Pinus resinosa, Pinus banksiana, Pseudotsuga menziesii, southern yellow pine) were fumigated with chloropicrin, methylisothiocyanate and Vapam and the rates of fumigant penetration determined. All three fumigants were applied directly into holes bored radially into the pole sections. Analysis for fumigants commenced after a few days at various sampling distances from the treating point. After three months the test was concluded. Methylisothiocyanate, diffused equally well upwards or downwards in the pole section from the point of fumigation in all wood species, and appears to offer the best potential of the three fumigants as a pole treatment in Canada. When applied directly, chloropicrin initially moved quickly but then the diffusion rate slowed somewhat. Upward movement was fastest in eastern white and western red cedar while downward movement was also rapid in southern yellow and red pine. Chloropicrin movement was rated as good in Douglas-fir but poor in jack pine. Diffusion of chloropicrin was severely retarded in lodgepole pine. In general Vapam movement was slow at first, and then increased with time. Diffusion rates for all wood species were similar except for relatively rapid upward movement in red and southern yellow pines.
J N R Ruddick

Three-dimensional modeling of fumigant distribution in wood poles
1993 - IRG/WP 93-30025
The practice of using fumigants to control internal decay has been widely accepted in the United States and has shown to be effect in control internal decay in transmission poles and other large wood timbers. Mathematical models were developed to simulate the chloropicrin movement in utility poles after treatment. The simulation results indicated that treatment of utility poles, using either traditional remedial treatment procedures or center-bore application procedures could provide long-term effectiveness in terms of eliminating existing infection and preventing further fungal attack. Controlled-release technology used in fumigant treatment was also shown to be potentially useful to reduce chemical usage and extend the protection period.
Jing Liu, B Goodell

Gelatin encapsulated fumigants for wood fumigations: Current research status
1985 - IRG/WP 3336
The fumigants chloropicrin (trichloronitromethane) and methylisothiocyanate (MIT) were encapsulated in gelatin as an alternative to liquid fumigant treatments for control of decay fungi in wooden utility poles. Gelatin-encapsulated MIT was stored for over 2 years under dry conditions without significant fumigant leakage. Gelatin encapsulated MIT and chloropicrin were released from capsules when placed in wood above the fiber-saturation point, although capsules were more permeable to MIT than chloropicrin. In field treatments, the addition of small quantities of water along with capsules was sufficient for fumigant release. Encapsulated MIT and chloropicrin treatments effectively reduced decay fungus populations in Douglas-fir utility poles.
A R Zahora, M E Corden, J J Morrell

Screening method to test efficacy of fumigants against fungi and preliminary data on the efficacy of sulfuryl fluoride
2014 - IRG/WP 14-20551
Methyl bromide is being phased out and there is an urgent need to find a suitable replacement that is effective in reducing exotic pest establishments via trade in wood products. Efficacy data for established phytosanitary fumigants were mostly developed for arthropods and nematodes, and limited information exists for plant pathogens. Increased interest in developing a fast screening process for fungi has prompted this work. Small scale sulfuryl flouride fumigations were conducted in 10 L chambers at six target concentrations (40-240 mgL-1) at 20 C for 24 h against 23 fungal species. Fungi were grown on barley/grain, which was placed in borosilicate glass tubes covered on both ends with a felt cloth to allow uninhibited gas penetration while minimizing the risk of fungal contamination. This allowed simultaneous testing of numerous species/isolates followed by 100% recovery of controls and without contamination of all other isolates exposed to six target sulfuryl fluoride concentrations. Preliminary data have shown that 13 out of 23 species survived the 240mgL-1 exposure. Additional research is needed to test efficacy against more isolates, and under different temperatures and exposure times before experiments closer to field conditions are conducted.
A Uzunovic, A Mukherjee, R Mack, P Elder, S Myers

Chemical Analysis of Southern Pine Pole Stubs Sixty Months Following Treatment with a Methylisothiocyanate-Based Solid Fumigant Stick
2019 - IRG/WP 19-30740
Methylisothiocyanate-based fumigants have been commercially used in the United States for over 35 years to control internal decay in utility poles and other wooden structures with little technological advancement. The most recently commercialized methylisothiocyanate-based fumigant is chemically known as dazomet. Dazomet is a free-flowing powder or granule that decomposes in the presence of moisture within a utility pole to release methylisothiocyanate. As a means to accelerate the decomposition to methylisothiocyanate, a copper solution can be applied to dazomet during the time of fumigant application. Laboratory and field studies conducted as part of the Utility Pole Research Cooperative at Oregon State University have demonstrated the long-term efficacy of dazomet. Concerns with applicator safety, inefficient copper-dazomet interaction, accurate dosing and a high potential for accidental spills, has led OSU researchers to develop several solid forms of dazomet. While long-term field testing by the OSU-UPRC has generated positive results, the prototype forms of solid dazomet had little commercial value. Recently, a commercially viable solid-stick dazomet product was introduced to the remedial wood preservative market to prevent and arrest active decay within in-service wood utility poles. To demonstrate the long-term performance characteristics of this solid form of dazomet, a field study was established in January 2014 in southern pine utility pole sections. At the fourth inspection conducted 60 months following fumigant treatment, chemical assay borings were removed at various pole heights and depths and analyzed for concentrations of methylisothiocyanate using GCMS. The 60-month results showed the concentrations of methylisothiocyanate were greatest in the pole sections treated with the copper amended solid-stick dazomet. When compared to previous chemical assay results at 12, 32 and 46 months following fumigant treatment, the 60-month results showed a sharp increase in concentrations of methylisothiocyanate in the copper amended solid-stick dazomet treated pole sections. The granular dazomet showed a slight increase in methylisothiocyanate production, where the unamended solid-stick and copper amended granular dazomet showed little change from 46 to 60 months of exposure. When compared to a methylisothiocyanate threshold value for decay fungi proposed by Oregon State University, the chemical assay results at 60 months indicated all fumigant treatments are effectively protecting the zone of fumigant treatment (15.2 cm below to 15.2 cm above groundline) of southern pine pole sections. However, the greatest protection within and above the zone of treatment was provided by the copper amended solid-stick dazomet treatment. Future sampling and chemical analysis of the southern pine pole sections are planned to monitor long term efficacy of the fumigant treatments.
D J Herdman, T Pope, R R Browning

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

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