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Insect resistance of preservative treated tropical plywood against Lyctus
1990 - IRG/WP 1453
Seven plywood types composed of tropical wood species, vulnerable to Lyctus, were treated with various commercial water-borne and oil-borne preservatives. A wide range of preservative retentions was obtained by treating boards with dip treatment, steeping, double-vacuum and vacuum-pressure impregnations. Selected samples were subsequently tested for their insect resistance against Lyctus africanus during 6 to 8 months according to European Standard EN 20. All control samples were attacked, except one Obeche plywood exhibiting only 50% attack. Water-borne preservative solutions containing arsenic, boron or fluoride could not prevent attack at common retention levels for interior use e.g. lower than 5 kg/m³. Quaternary ammonium compounds showed no insecticidal efficiency, up to 3 kg/m³. TCMTB at 1.5-1.7 kg/m³ proved to be able to reduce slightly the susceptibility for insect attack. Organic insecticides gave the best results, with nearly no attack for plywood treated with lindane or cypermethrin. In spite of a preservative uptake of 25 to 30 kg/m³, endosulfan only could reduce attack by 50%. Protection by permethrin at 0.1% a.i. required a retention of 28 kg/m³. Besides the fact that variability in wood species and composition of the plywood are leading to different retention levels, variation in penetration and distribution of a.i., and as a consequence to a different insect resistance of the impregnated boards, some poor results were directly related to inadequate insecticidal activity and/or concentration of a.i. in some commercial formulations for Lyctus control.
J Van Acker, M Stevens, M Pallaske


Exposure trial at tropical marine sites of pyrethroid/creosote mixtures as wood preservatives: Preliminary results
1989 - IRG/WP 4155
Pinus sylvestris sapwood blocks measuring 25 x 25 x 200 mm³, impregnated using a Lowry or Rüping pressure treatment cycle with solutions of permethrin, cypermethrin or deltamethrin in BS144 creosote, have been exposed at marine sites in Australia, Papua New Guinea, the U.K. and Singapore. The effectiveness of these solutions in preventing marine borer attack is being compared with the efficacy of creosote alone, creosote/CCA double treatment, pyrethroids alone and no treatment. Blocks at the tropical sites have been installed in the intertidal zone in areas where the crustacean borer, Sphaeroma is active. Teredinids (shipworms) of several species are very numerous at these sites and the bivalve borer, Martesia, is present. Limnona colonies were found in untreated blocks at the sites in Papua New Guinea and Australia. The results of inspections after exposure periods of up to 26 months at the tropical sites are summarised in this report. Untreated sample blocks failed rapidly to borers, particularly teredinids. Pyrethroids alone reduced the level of crustacean borer attack and to a lesser extent, teredinid attack. All blocks treated with creosote-containing solutions have so far not been attacked by borers or degraded significantly by micro-organisms. Soft-rot and bacterial degradation occurred in untreated blocks and blocks treated with pyrethroids alone. Settlement by barnacles and serpulid worms appears to be inhibited by the creosote/CCA double treatment, but there is no evidence of long-term inhibition of barnacle or serpulid settlement by pyrethroid-containing solutions, whether with creosote or without. Samples at the site in the UK are exposed to teredinid attack. No inspections have yet been carried out at this site.
S M Cragg


Surveillance médicale des personnels exposés aux produits de préservation du bois
1990 - IRG/WP 3588
J-C Aubrun


Laboratory study on the effectiveness on photostable pyrethroids formulated with benzalkonium chloride to be used on furniture
1985 - IRG/WP 3346
The first results are presented of a study on the effectiveness of photostable pyrethroids formulated with banezalkonium chloride. Initially the products were submitted to preliminary tests and then the more efficient formulations were tested with a new essay that tries to simulate a dry-wood termite attack on furniture.
A M F Oliveira, A T De Lelis


The use of pyrethroids against Limnoria spp
1981 - IRG/WP 473
Synthetic pyrethroid insecticides discovered in the last fifteen years have been developed as crop sprays and used in aerosol formulations for the control of household pests. High toxicity to a wide range of arthropod pests, combined with reasonably low mammalian toxicity, confers an advantage over many other control agents. Some of the more recent pyrethroids are photostable and display residual activity, ant hence are being considered as potential wood preservatives. Work at the Building Reaearch Eatablishment, Princes Risborough, Bucks., England, has concentrated on the use of pyrethroids in remedial wood treatment while at Portsmouth Polytechnic, England, the areas of preservation of wood in the marine environment and the protection of timber against termite attack have been investigated. The present document summarises an investigation into the effectiveness of aynthetic pyrethroids against the marine borers, Limnoria spp.
D Rutherford, R C Reay, M G Ford


Test of N-tritylmorpholine in combination with synthetic pyrethroids against marine borers in tropical Australia and Panama
1991 - IRG/WP 4168
Test blocks ol Pinus sylvestris sapwood were pressure impregnated with white spirit solutions of N-tritylmorpholine, either alone or in combination with permethrin, deltamethrin or cypermethrin. They were exposed in the intertidal zone at Mourilyan Harbour, North Queensland, Australia and subtidally at either end of the Panama Canal. After 5 months' exposure at Naos Island at the Pacific end of the Canal, all blocks were attacked by the pholad bivalve, Martesia striata. At Mourilyan Harbour, after exposure for one year, all blocks were riddled with teredinid borers, irrespective of type of preservative treatment. Attack by limnoriid borers, on the other hand, was restricted to blocks which contained no pyrethroids. A 0.1% m/v solution ol N-tritylmorpholine applied by pressure provides no significant protection for wood from molluscan marine borers.
S M Cragg, J D Bultman


The residual effects of remedial timber treatments on bats
1986 - IRG/WP 1281
By means of controlled laboratory experiments it was established that timber treatment fluids containing g-HCH and pentachlorophenol (PCP) and used according to manufacturers recommendations rapidly cause the death of pipistrelle bats roosting in contact with timber treated between six weeks and 14 months previously. The chemicals responsible are presumably ingested when the bats groom their fur after they have been in contact with the treated timber. Bats prevented from establishing such bodily contact took longer to die indicating that absorption of the vapour phase of the tested chemicals also takes place across the skin or respiratory epithelium. Acrylic resin reduces the lethal effect when used as a sealant over wood treated with g-HCH and PCP, but polyurethane varnish does not. It has also been established that no obvious harm is caused to bats roosting for 16 to 22 weeks in contact with timber treated with the synthetic pyrethroids permethrin, cypermethrin and deltamethrin at concentrations which have previously proved effective for the control of woodboring beetles. Similarly, no obvious harm is caused to bats roosting for 14 weeks in contact with timber treated with the fungicides borester-7 and zinc octoate. However, greater mortality was recorded in bats housed in cages treated with the fungicide tributyltin oxide than in control groups. It is clear from these results that synthetic pyrethroids should replace g-HCH for the treatment of wood-boring beetles in bat roosts. A high priority should be accorded to replacing PCP with a fungicide which is not toxic to bats.
P A Racey, S M Swift


An evaluation of the synthetic pyrethroid cypermethrin in organic solvent and emulsion formulations
1984 - IRG/WP 3290
The studies reported indicate that cypermethrin (NRDC 149) has considerable potential as an insecticide for wood preservatives. Cypermethrin appears to be about twice as effective as permethrin. The effectiveness of cypermethrin compared with g-HCH varies depending on the insect species, the phase of the life cycle and size of larva: for example, against mature Anobium larvae cypermethrin is approximately equal to g-HCH in effectiveness, but against egg larvae it is four times more effective. Against emergence of Anobium adults an organic solvent formulation containing 0.1% cypermethrin was more effective at 16 months than the g-HCH solution which was ten times stronger. Against mature Hylotrupes larvae it is approximately four times more active than g-HCH but as a surface spray against Lyctus a concentration of cypermethrin fifty times less than that used commercially for g-HCH spray treatments prevented infestation. Bioassay tests with a range of wood-boring insects reveal broad spectrum activity and considerable resistance to standardised accelerated evaporative ageing. In emulsion formulation cypermethrin at 0.1% prevented emergence of Anobium adults for 5 years, and was effective against attack by termites. A 0.01% emulsion formulation prevented infestation by Lyctus. In organic solvent formulation 0.1% cypermethrin gave an acceptable level of mortality against both Anobium and Hylotrupes larvae and prevented emergence of Anobium adults at 26 months.
S J Read, R W Berry


Persistance of active ingredients in treated wood
1993 - IRG/WP 93-50001-20
Disposing of chemically protected waste wood implies the distinction between surface and pressure treatment. Considering that barked round-wood merely contains, after 7 months open storage, less than 30 g per ton of bark or 25 mg per ton of sapwood, depending on the type of insecticide, the bark or sapwood shavings may be incinerated normally, according to less severe legal prescriptions than for pressure treated wood. Past use poles, destroyed by fungi, will indeed have to be disposed of in specially equipped incineration plants, which respond to strict requirements regarding the waste air.
E Graf, P Manser, S Rezzonico, B Zgraggen


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


The effect of synthetic pyrethroid insecticides on post-treatment emergence of Anobium punctatum
1992 - IRG/WP 92-1568
Data is presented from trials in which wood specimens, treated with a range of remedial insecticidal formulations, were aged in a roof void for 5 years and then tested for emergence of adult Anobium punctatum. The technique used followed that described in IRG/WP/2175. The results from formulations containing synthetic pyrethroids are compared with those from formulations containing the chlorinated hydrocarbon insecticides lindane and dieldrin, which have given satisfactory effectiveness in commercial use in the UK for several decades. None of the formulations containing either synthetic pyrethroids or chlorinated hydrocarbons and based on organic solvent allowed any emergence of adult beetles. All of the emulsion-based formulations, with the exception of one based on 1% dieldrin, allowed some emergence. This varied between 4% and 8% of the larval population of the specimens compared with 57% for untreated control. The significance of the levels of emergence observed in treated specimens is discussed in relation to efficacy in practice and it is concluded that further work is necessary to calibrate the results from test method in relation to efficacy.
R W Berry


Laboratory tests on the residual effects of pyrethroids against termites thirteen years after application
1994 - IRG/WP 94-30056
This paper is in continuation to a series of articles published on the work being developed in Brazil regarding the feasibility of using photostabl synthetic pyrethroids against termites. Tests were carried out to compare the efficacy of five synthetic pyrethroids with the traditional organo-chlorinated pesticide, chlordane. Wooden blocks were impregnated with alcohol-based solutions of the above-mentioned products at four different concentrations, and 13 years later these blocks were exposed to dry-wood termites. Results of these tests showed that Deltamethrin, Cypermethrin and Fenvalerate were still effective after this period of time.
A M F Oliveira


Pyrethroids: Isomerism and efficacy
1986 - IRG/WP 1284
Pyrethroids are drawing increasing attention to the wood preservative formulators because: ( 3; 6) a) pyrethroids reveal good efficacy against a large variety of wood boring insects by contact. b) pyrethroids show good long term efficacy because of their high stability in timber. c) mammal toxicity is relatively low ( e.g. bats) (9). d) pyrethroids are almost odorless. It was found that different methods of pyrethroid synthesis result in different ratios of isomers (1). Special effort was put into the proof of the reciprocal relationship between cis-percentage of an isomeric pyrethroid mixture and its toxic value against wood boring insects. Permethrin (52645-53-1), an ester of the chlorine derivative of phenoxybenzylalcohol and vinyldimethylcyclopropancarboxylic acid is on the market as a (±) cis/trans-isomeric mixture between 60:40 and 25:75. The ratio 25:75 compromises between efficacy and toxicity.
R Gruening, R Pospischil, S Cymorek, W Metzner


Qualitative and quantitative assessment of chemicals used for wood durability improvement by Near Infrared Spectroscopy
2006 - IRG/WP 06-20349
The Near infrared spectroscopy (NIRS) could be a suitable technique to assess chemicals used for wood durability improvement in the forest products industry. NIRS methodology can be used to obtain results more quickly, less costly and without damaging the wood. In this study, wood samples selected from heartwood and sapwood of Maritime Pine (Pinus pinaster) were prepared to assess the artificial durability by NIRS technique. Pieces of veneer (strips) of Maritime Pine were impregnated by wood preservatives containing active components such as boric acid, copper, cypermethrin, IPBC, permethrin, propiconazol, and tebuconazol. Four commercial products sold for industrial wood protection from different companies were tested. Three steeping times were used in order to obtain three concentrations of each product. They were applied on 120 strips of wood by products, 20 per concentration for both heartwood and sapwood. Partial Least Squares (PLS) technique was used to calibrate NIR spectra collected. In this preliminary study, we expose the first results on qualitative and quantitative assessment by using NIRS technique of chemicals used for wood durability improvement. It was possible to distinguish between raw and commercial products treated Maritime pine wood containing organic and inorganic preservatives. This shows the potential of NIRS technique which could be used efficiently in rapid identification and quantification of organic and inorganic wood preservatives.
S Zahri, F Charrier, H Baillères, B Charrier


Laboratory bioassay and field trial on imidacloprid and cypermethrin as glueline treatments for softwood plywood
2006 - IRG/WP 06-30405
The effectiveness of imidacloprid and cypermethrin as glueline treatments for protecting phenol formaldehyde (PF)-bonded Pinus radiata (radiata pine) plywood from attack by subterranean termites was evaluated both in the laboratory and field. Imidacloprid was evaluated in two plywood constructions (19 ply x 1.6 mm-thick veneers and 5 ply x 3.2 mm-thick veneers) whereas cypermethrin was evaluated in only one (19 ply x 1.6 mm-thick veneers). There was a strong correlation between the results obtained from the laboratory bioassay and the subsequent field trial. Results of both the laboratory bioassay and field trial demonstrated that imidacloprid at the retention of 20 g a.i./m3 failed to adequately protect test specimens of radiata pine plywood (19 ply x 1.6 mm-thick veneers) from attack by both Coptotermes acinaciformis and Mastotermes darwiniensis. However, it was noted that imidacloprid only marginally failed against attack by C. acinaciformis in the field. In contrast, imidacloprid at the retention of 20 g a.i./m3 was successful in protecting test specimens of radiata pine plywood (5 ply x 3.2 mm-thick veneers) from significant attack by C. acinaciformis, but comprehensively failed against M. darwiniensis. Cypermethrin at the retention of 420 g a.i./m3 was successful in protecting test specimens of radiata pine plywood (19 ply x 1.6 mm-thick veneers) from significant attack by C. acinaciformis. The same retention of cypermethrin performed well in protecting radiata pine plywood test specimens from attack by M. darwiniensis, even though it marginally failed in the laboratory. It is hypothesised that the longer hot pressing time used for the manufacture of plywood test panels of 19 ply x 1.6 mm-thick veneers may have caused more degradation of the imidacloprid active than in panels of 5 ply x 3.2 mm-thick veneers.
J W Creffield, D K Scown


VOC-free remedial treatment agent on organic solvent basis with surface cleaning by photocatalysis using titanium dioxide
2014 - IRG/WP 14-40651
Due to the EU Regulations according to the harmonisation of the European market of biocidal products and the EU Regulations regarding emissions of volatile organic compounds in residential properties a new VOC free yet organic solvent based remedial treatment agent is introduced including a potential method to clean up the wooden surface of remaining biocides after a remedial treatment using photocatalysis.
H Ahl, J Fromm, P Jüngel, E Melcher, M Pallaske


Termiticide Residues in Gravel Fill
2014 - IRG/WP 14-20553
Downward dispersion of liquid termiticide in gravel was determined by measuring active ingredient (a.i.) residues of two frequently applied liquid pyrethroid termiticides during one year following surface applications at lowest label rates (Up-Cyde Pro® 2 EC-cypermethrin; BaseLine® EC-bifenthrin) over the two most extensively used commercial building construction gravel foundation fills in Oklahoma. Residues were determined within partitioned depths in the two fills at 24.0 hours post-application, then after 6.0 and 12.0 months. Half the test plots were compacted (12-15% weight increase per unit volume) and half were not compacted. Downward dispersion of termiticide was significantly influenced by gravel type, regardless of whether compacted or not compacted. Dispersion of both termiticides in compacted plots compared with not-compacted plots was similar for Class A-#57 Crushed Rock, as residues were near evenly distributed throughout the entire 0.0- to 10.2-cm depth. However, for ODOT (Oklahoma Department of Transportation) Base Type-A Gravel, residues were greater in the top partition for both compacted and not-compacted plots. Residue differences were less pronounced when comparing within the same depth partitions only. Generally, residues within ODOT Base Type-A Gravel were retained in significantly greater amounts within the top partition depth, surface 0.0- to 5.1-cm deep, for both termiticides (cypermethrin: 115-118 ppm; bifenthrin: 43-44 ppm) compared with Class A-#57 Crushed Rock (cypermethrin: 27-33 ppm; bifenthrin: 8-21 ppm) at 24.0 hours after applications. These differences were less pronounced within the 5.1- to 10.2-cm partition depth. Total a.i. recovered accounted for ≈83-95% of amounts applied to ODOT Base Type-A Gravel, whereas residues recovered from Class A-#57 Crushed Rock ranged from ≈38-65% of applied amounts. This reduced recovery percentage is due to some of the termiticides dispersing downward completely through the Class A-#57 Crushed Rock and into the mineral soil beneath. Therefore, termiticide residues in the underlying soil were not recovered during sampling of the gravel fills. For ODOT Base Type-A Gravel, most of the termiticide residues that were recovered (≈59-81%) were retained in the top 5.1-cm-deep partition. Almost no residues of either termiticide (0.0 to <1.0 ppm) applied over both compacted and not-compacted ODOT Base Type-A Gravel dispersed downward deeply enough to reach underlying mineral soil.
B M Kard, C E Konemann, K T Shelton, C C Luper, R A Grantham, M E Payton


Above ground field testing: results of experiments in Brazil after one year
2015 - IRG/WP 15-30660
After the development of new products they need to be field-tested to assess their efficacy under diverse conditions of climate, comparing them with a preservative with proven efficacy. In some testing sites, decay occurs very slowly. The solution would be to bring these tests to locations that are conducive to biodeterioration, like tropical climates. Tropical sites provide higher temperature and humidity, which are excellent environmental conditions for wood biodegradation. Adaptations of four internationally-recognized standards were used to evaluate the effectiveness of wood preservatives products softwood in a species with no natural resistance (Pinus sp.). The assessment consisted of the simulation of aggressive environment for wooden structures used outdoors, such as door frames and window frames, decks and facades accompanied by a protective varnish coating in half of the specimens. This paper presents the preliminary results, after one year of exposure, of new wood preservative products developed for specific Brazilian climatic conditions. Due to the short duration of the test to this date, there are no significant variations among the performances of the various products. During one year there was a reduction in the deterioration rate caused by fungi and termites.
M F Natale, J M Vidal


Development of a new characterization method to analyse Cypermethrin penetration in wood material by immunolabelling
2015 - IRG/WP 15-30674
The preservative efficacy of organic biocides is strongly related to their capacity of penetration and retention within wood tissues. The specific detection of the pyrethroid insecticide cypermethrin is currently obtained after extraction followed by chemical analysis by chromatography techniques. However visualizing the insecticide molecule within the wood structure requires specific probes together with microscopy techniques. Therefore, the aim of the present work was to apply a new methodology based on antibody-antigen recognition and electronic microscopy to visualize directly cypermethrin in wood material. A polyclonal antibody directed against cypermethrin was developed and implement it on Pinus sylvestris wood samples coated with technical cypermethrin. The antibody was tested on cypermethrin-impregnated wood and the specific recognition of the insecticide was visualized in transmission electron microscopy (TEM). The immunogold-TEM assay evidenced the capacity of the synthetic biocide to penetrate in the wood. The depth of penetration was measured on sections taken at increasing distances from the coated surface of the wood. In the present conditions of application, cypermethrin was shown to penetrate up to the 6-9 mm zone below the surface. Such results correlated with chemical analyses carried out by GC-ECD after extraction. In addition, the immuno-TEM investigation allowed visualizing, for the first time at the ultrastructure scale of resolution, that cypermethrin was able to diffuse within the secondary wood cell walls. The scarce labeling of the compound middle lamella shows that the chemical does not diffuse freely in this part of the cell walls. The results suggest that the adsorption within the cell walls is an essential factor of the retention of cypermethrin and of its permanence in wood-treated materials and products.
S Tapin-Lingua, K Ruel, J-P Joseleau, D Messaoudi, O Fahy, M Jequel, M Petit-Conil


Termiticide Residues in Building Foundation Aggregate Fills After Trench and Surface Applications
2015 - IRG/WP 15-30679
Termiticide concentrations (ppm) in aggregate fill were determined by measuring active ingredient (a.i.) residues of two pyrethroid termiticides, Up-Cyde Pro® 2EC-cypermethrin, and BaseLine® EC-bifenthrin, at 24.0 hours, and then at 6.0- and 12.0-months after ‘horizontal’ surface applications, perimeter ‘trenching and rodding’ applications, or ‘rodding only’ trench applications at lowest label rates to two common building construction aggregate foundation fills often used in the state of Oklahoma, USA. Residues were determined within 5.1-cm-deep multiple-core composite aggregate fill samples extracted after surface applications, and 15.2-cm-deep multiple-core composite samples extracted from interior foundation perimeter trenches. Before termiticide applications were conducted, all test plots were raked to a level surface, then half the test plots were compacted and half remained not compacted. Residue concentrations were significantly influenced by aggregate fill type, regardless ofwhether compacted or not compacted.
B M Kard, C E Koneman, K T Shelton, C C Luper, R A Grantham


Superior kempas hardwood protection with two proprietary microemulsion termiticdes based on permethrin and cyermethrin against Coptotermes termite attack under H2 an H3 weathered conditions found in buildings
2018 - IRG/WP 18-10931
SARPECO® and AXIL® solutions are water-based wood preservatives approved for dipping treatment providing 25 years of termite protection for solid wood and wood-based products in Europe and for more than 10 years in Indonesia. SARPECO® and AXIL® solutions are patented formulations based on concentrated microemulsions (ME) diluted with water as a dipping treatment but also for vacuum pressure treatment. Field trials conducted in Malaysia by UNIMAS confirmed the efficacy of SARPECO® and AXIL® solutions at three product concentrations on short dip-treated kempas (Koompassia malaccensis) heartwood, a major hardwood species in the Malaysian wood construction market, against the Southeastern Asian subterranean termite Coptotermes curvignathus exposed to aboveground H2 (indoor, non-wetting conditions) hazard class targeting termites compared to CCA-treated kempas and radiata pine (Pinus radiata) sapwood. Prior to the H2 hazard class termite field test exposure, treated wood blocks were conditioned to either a non-leaching volatilization (H2 hazard class weathered wood blocks) or to a leaching followed by volatilization (H3 hazard class weathered blocks) as well as non-leaching/non-volatilization and leaching/non-volatilization reference treatments. After 6 months field exposure, untreated kempas was severely (termite ratings: 0, mean mass loss: 97.4%) or moderately attacked (mean ratings: 7.7, mean mass loss: 17.5%), while none of the leached-volatilized (H3 hazard class) or non-leached-volatilized (H2 hazard class) test blocks treated with SARPECO® and AXIL® at both target retentions were regarded as attacked (mean ratings: 9.7-10, negligible mean mass loss) regardless of applied termiticide concentration, leached or non-leached wood, volatilized or non-volatilized wood treatments. Excellent performance also prevailed with the remaining treatment combinations of treated wood. Due to their unique compositions, SARPECO® and AXIL® solutions showed excellent performance against Coptotermes curvignathus with low termiticide concentrations where conventional agro-insecticides do not work. In conclusion, SARPECO® and AXIL® are effective for wood protection in buildings against Southeast Asian Coptotermes subterranean termites.
D Messaudi, A H H Wong, C A D Tawi, N Bourguiba, O Fahy


A non-VOC approach of solvent-based wood preservatives for remedial treatment
2016 - IRG/WP 16-30681
Solvent-based wood preservatives are the workhorses in the field of remedial treatment. Due to new European regulations on the indoor air quality there is an increasing pressure on the VOC-content on these solvent-based product types. The transfer of these European regulations into national law is left up to each European member state and handled in different ways. E.g. France has introduced a VOC-classification system based on ISO 16000 and leaves the product selection up to the customer, in Germany the national building authority has established - based on the AgBB test procedure - binding delay times between treatment and the normal re-use of the facility. The VOC-issues can be approached in two different ways. Either by decreasing the VOC-exposure time by selecting a highly volatile solvent/co-solvent combination or by keeping the VOC-exposure below the regulatory limits by selecting a solvent/co-solvent combination of very low volatility. This study presents two approaches to cope with the VOC-issues of solvent based remedial wood preservatives. The first approach was to decrease the VOC-exposure time by selecting a highly volatile solvent/co-solvent combination. It ended up in wood preservative formulations with non-acceptable inflammability properties. In the second approach a complete avoidance of VOC-emissions could be achieved by making use of a non-volatile solvent with sufficient dissolving power to directly dissolve the insecticide. This type of product showed a slightly better penetration performance compared to a standard VOC-containing “low odour”-version based on isoparaffins with directly dissolved insecticide. Considerable differences in the distribution of the biocide can be seen between volatile and non-volatile solvent based formulations. While in non-volatile solvents the insecticide stays where the solvent is, the volatile solvent based formulation showed a slight superficial insecticide accumulation resp. a slight depletion inwardly. In addition to the comparative performance test of a volatile solvent- and a non-volatile solvent-based formulation, the impact of the co-solvent on the insecticide penetration of a standard "white spirit"-formulation was demonstrated. Whenever the carrier-solvent is unable to directly dissolve the insecticide, the biocide-distribution becomes determined by the properties of the co-solvent and/or by co-solvent/carrier-solvent interactions. It was shown, that an efficient but unsuited co-solvent in a dearomatised hydrocarbon-carrier solvent could on the one hand side nearly completely stop the insecticide penetration within the first 2.5 mm below the treated surface, but showing no effect on the distribution of the carrier-solvent on the other hand side.
M Pallaske, S Hellkamp, P Jüngel


Exemplary aboveground hardwood protection from Coptotermes curvignathus under weathered conditions conferred by proprietary microemulsion-based cypermethrin (SARPECO®) and permethrin (AXIL®) biocides
2019 - IRG/WP 19-30749
SARPECO® (with cypermethrin) and AXIL® (with permethrin) solutions are water-based wood preservatives approved for dipping treatment providing 25 years of termite protection for solid wood and wood-based products in Europe and for more than 10 years in Indonesia. SARPECO® and AXIL® solutions are patented formulations based on concentrated microemulsions (ME) diluted with water as a dipping treatment but also for vacuum pressure treatment. Field trials conducted in Malaysia by UNIMAS confirmed the efficacy of SARPECO® and AXIL® solutions at three product concentrations (norminal cypermethrin concentrations used: 0.08, 0.16 & 0.32%w/w; norminal permethrin concentrations used: 0.05, 0.10, 0.20 %w/w) on 3-minutes dip-treated kempas (Koompassia malaccensis) heartwood, a major hardwood species in the Malaysian wood construction market, against the Southeastern Asian subterranean termite Coptotermes curvignathus. Such treated wood blocks were exposed to aboveground H2 (indoor, non-wetting conditions) hazard class termite field test and compared with CCA-treated kempas heartwood and radiata pine (Pinus radiata) sapwood. Prior to the H2 hazard class termite field test exposure, treated wood blocks were conditioned to either a non-leaching volatilization (H2 hazard class weathered wood blocks) or to a leaching followed by volatilization (H3 hazard class weathered blocks) as well as non-leaching/non-volatilization and leaching/non-volatilization reference treatments. After 6 months field exposure, untreated kempas was severely (termite ratings: 0, mean mass loss: 97.4%) or moderately attacked (mean ratings: 7.7, mean mass loss: 17.5%), while none of the leached-volatilized (H3 hazard class) or non-leached-volatilized (H2 hazard class) test blocks treated with SARPECO® and AXIL® at both target retentions were regarded as attacked (mean ratings: 9.7-10, negligible mean mass loss) regardless of applied termiticide concentration, leached or non-leached wood, volatilized or non-volatilized wood treatments. Excellent performance also prevailed with the remaining treatment combinations of treated wood. Due to their unique compositions, SARPECO® and AXIL® solutions showed excellent performance against Coptotermes curvignathus with remarkably low termiticide concentrations where conventional agro-insecticides fail to perform. In conclusion, SARPECO® and AXIL® are effective for wood protection in buildings and outdoors aboveground against Southeast Asian Coptotermes subterranean termites.
D Messaoudi, A H H Wong, C A D Tawi, N Bourguiba, O Fahy


Monitoring uptake and penetration of pesticides during impregnation of pine (Pinus sylvestris) and spruce (Picea abies) wood with bio-based microemulsion gel formulations
2020 - IRG/WP 20-30756
Even in dry state wood is susceptible to biological degradation. Preservation against biological decay in exposed conditions is conventionally achieved by impregnating the wood with pesticides applied at professional and industrial levels. Impregnation of wood with preservatives is a complex process that involves wood macro- and microstructure, and the physical characteristics of woods. Here we focused on pine (Pinus sylvestris), an easily impregnable species, as opposed to spruce (Picea abies), a refractory species. In this work, the two species were impregnated with commercial bio-based emulsion formulations containing insecticide and fungicide agents. Penetration and uptake of the active agents were evaluated on laboratory specimens. The impact of different modes of application, dipping, surface spraying, and vacuum-impregnation, on the retention and distance of penetration of the active agents, cypermethrin, permethrin and propiconazole was assessed by gas liquid chromatography coupled to mass spectroscopy. Due to the suitable combinations of solvents and surfactants of our bio-based emulsions of low-toxicity and minimal environmental impact, rapid wood penetration enabled high retention yields. The difference of penetrability of pine versus spruce is discussed in relation to their anatomical characteristics, and their conducting cells network. The present data demonstrate the penetration and retention performances of these bio-based formulations.
D Messaoudi, K Ruel, J-P Joseleau