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Leaching of components from water-borne paints and fungitoxic effects
1995 - IRG/WP 95-20062
Water-borne model paints, acrylics and alkyd emulsion paints, of known composition were leached according to a procedure modified in accordance with ASTM 6271.1. The effectiveness of fungicidal compounds in the painted specimens before and after leaching was evaluated with a biotest in which Penicillium brevicompactum was used as a test fungus. The leaching of the fungicide Troysan Polyphase according to the biotest varied to a high extent depending on differences in paint composition. Fungicide efficiency in relation to paint formulation and fungicide mobility in a paint film is briefly discussed.
J Bjurman


Comparative evaluation of the barrier effect against Hylotrupes bajulus L. of different types of wood preservative
1986 - IRG/WP 1307
This paper settles the difference of contact action against females of Hylotrupes bajulus the likelihood of egg-laying, the ovicide effect and the hazards of development of newly hatched larvae between some preservatives belonging to three differents types: mineral waterborne products, organic products and emulsions. The results show that against females, the action is fast with organic products, slower with emulsions and non existent with mineral products. They point out the relation between the longivity of females and the eventuality of egg-laying. With ageing, this latter become possible for almost every preservative. In the most of cases, the larvae hatch from eggs and can bore into wood until they accumulate the lethal dosis and that occurs more or less fastly. A few differences are observed for preservatives of the same category.
M-M Serment


Water-repellent additive for CCA
1991 - IRG/WP 3655
Hickson have developed a water repellent additive for incorporation into copper-chromium-arsenate timber treatment solutions. The water repellent emulsion shows good stability in the treatment solution, is easily incorporated and applied in a single stage treatment. No modifications to the additive is safe to treatment schedule are usually needed and use. Weathering of the treated wood is substantially inhibited by the presence of the additive. Adhesion of paints is not affected.
P Warburton, R F Fox, J A Cornfield


A laboratory method for assessing the effectiveness of remedial treatments in preventing post-treatment emergence of Anobium punctatum
1982 - IRG/WP 2175
R W Berry


Influence of pre-swelling conditioning on swellometer results for CCA and water repellent additive treated wood
1997 - IRG/WP 97-20125
The pre-test moisture content and conditioning history of wafers cut from wood treated with CCA and an emulsion water repellent additive can dramatically influence swelling curves generated using a standard swellometer apparatus. The rate of water uptake and swelling increased significantly as wafers were dried to lower moisture contents prior to immersion swelling. The pre-swelling conditioning history can also influence swellometer curves and confuse the interpretation of relative water repellent efficacy of emulsion water repellent systems. Results support that careful pre-conditioning of wafers is critical for meaningful comparisons of the relative efficacy of water repellent emulsion systems.
A R Zahora


Treatment of lumber with preservative/water repellent emulsions - The significance of shear stability on penetration
1997 - IRG/WP 97-20124
Currently, the treatment of lumber with a water repellent emulsion and a wood preservative formulation in combination is the most cost effective way to prevent decay and to maintain the appearance of uncoated lumber in service. Water repellents influence the movement of moisture into and out of wood and, by so doing, can decrease checking and splitting significantly. Adequate penetration of the emulsion and the preservative alike are important guarantors of performance for such preservative systems. The inherent particle size of an emulsion will influence its penetration into wood but our studies have indicated that the shear stability of the emulsion is also important. Results from a series of treatment trials using wood and a model system are discussed. A simple method has been developed to semi-quantitatively compare the shear stability of emulsion water repellents.
F Cui, K J Archer


Evaluating the performance of preservative/water repellent emulsion systems
1997 - IRG/WP 97-20127
Water repellent emulsions are being combined with wood preservatives to improve the weathering properties of treated wood in service. Unfortunately, few standard procedures are available to objectively compare the performance of these systems and as a result quality issues are almost completely neglected. The value of swellometer tests, water immersion tests and accelerated weathering regimes in the understanding of water repellent performance is discussed. This paper represents a step towards the development of water repellent standards which will serve to protect both the interests of the consumer and the wood treating industry.
K J Archer, F Cui


A preliminary assessment of the penetration into wood achieved by bodied mayonnaise emulsion wood preservatives
1992 - IRG/WP 92-3725
Five different commercial formulations of bodied mayonnaise emulsions were applied to samples of Scots pine (Pinus sylvestris) sapwood as recommended by the manufacturers. Penetration and loading characteristics were determined by measuring the distribution profiles of the active ingredients after various intervals of time. The changes in the general appearance of the emulsions on the surface of the treated wood was also observed. It was concluded that the nature of the formulation can affect the speed and extent of penetration of the active ingredients into the timber and that the simple expedient of applying more emulsion to the surface of the wood does not necessarily lead to increases in penetration and loading. Application of bodied mayonnaise preparations appears a reasonable option for the remedial treatment of insect attack, particularly where spot treatment is adequate. However, treatment against wood-destroying fungi may not provide sufficient protection in the longer term where the risk of attack is relatively high. It is recommended that further work be carried out to confirm the findings of this limited study.
G E Holland, R J Orsler


Occupant re-entry times following insecticidal remedial treatments of timber in dwellings
1995 - IRG/WP 95-50055
This work was carried out principally to obtain quantitative data on the aerial concentrations of permethrin and white spirit likely to arise following the remedial treatment of timber in buildings, using insecticidal formulations. Such data are needed to allow assessments to be made of the length of time buildings should remain unoccupied following such treatments prior to re-occupation, and the likely levels of exposure of the occupants to the treatment products concerned. Two large, free-standing, wood-lined chambers were treated (in separate experiments) with a dilute oil-in-water emulsion and a micro-emulsion, both containing 0.2% m/m permethrin. The atmospheres in the chambers were sampled at intervals and analysed for their permethrin content. In addition, the aerial concentrations of white spirit were determined following treatment with the dilute oil-in-water emulsion. Results indicated that the aerial concentrations of permethrin following treatment never exceeded 20 µg/m³. Comparison of the measured levels with the threshold limit value (TLV) for permethrin (modified to a TLV/40 to represent the value associated with 24 hours-a-day continuous occupancy) indicated that such levels of permethrin constituted no significant risk to occupants. Aerial concentrations of white spirit in the test chambers from the dilute oil-in-water emulsion product indicated by calculation that the TLV/40 of this solvent would be attained approximately 10 hours after treatment in a model domestic situation having the relatively low air exchange rates of the test chambers. This work has shown the importance of further studies needed to identify the rate determining step in the evaporation of deposited constituents from the surface of timber and to quantify the effect of different air exchange rates in treated premises on the aerial levels of formulation constituents.
R J Orsler, G E Holland, G M F Van Eetvelde


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


Losses of pyrethroids from treated wood due to photodegradation
1998 - IRG/WP 98-30177
The fact that significant photodegradation of pyrethroids can occur in use has been established for over 20 years. It is known, mainly from experience with tsetse fly control, that such degradation leads to marked reductions in efficacy. This realisation has lead to extensive investigation into ways of stabilising this group of important insecticides. Pyrethroids are widely used as the insecticidal component of pre-treatment wood preservatives, in addition to being important components of remedial treatments. However, studies on the longevity of pyrethroids in wood are limited and work to date has concentrated almost exclusively on the effects of temperature and humidity, either in soil contact or remedial treatment situations. The current study reviews experience with pyrethroid degradation in other end-use areas. Such findings are also considered in the context of preliminary exposure trials which suggest significant losses of synthetic pyrethroids from timber during a construction period. In the UK, water-borne emulsions of insecticide and fungicide mixtures are being increasingly used in preference to light organic solvent preservatives, prompted by ever stringent VOC-emission limits. This change in carrier-system, the situation in mainland Europe for some time, is likely to exacerbate any photodegradation problems with pyrethroids since emulsions tend not to penetrate as deeply into the timber as solvent-borne preservatives. Such implications are discussed, not least because the requirements for standard pre-conditioning and minimum penetration requirements may need to be revised for photo-labile active ingredients.
J D Lloyd, M W Schoeman, F Brownsill


Further progress towards a cleaner creosote treatment - Summarised report
1984 - IRG/WP 3304
This document provides an up-dated progress report on our development of pigment emulsified creosote (PEC) used as a cleaner alternative to conventional high temperature creosote. A range of commodities (both hardwood and softwood) has now been satisfactorily treated in pilot plant and full scale commercial operations. Both brown (PEC 30B) and white (PEC 30W) formulations have been used. In addition a number of biocides have been added to PEC 30B in order that wood may be treated to lower overall creosote levels while still retaining full preservation performance. It is anticipated that PEC will be used to treat a wide range of hardwood and softwood commodities.
H Greaves, C-W Chin, J B Watkins


Clean creosote - its development, and comparison with conventional high temperature creosote
1983 - IRG/WP 3235
Pigment emulsified creosote (PEC) is presently being tested and shows considerable stability in terms of water content, pigment level, pH, viscosity, rheological behaviour and microscopy. Timber samples from several eucalypt species have been treated with PEC and side matched samples treated with conventional high temperature creosote (HTC). The PEC treated specimens showed higher weight retentions of total preservative, (based on sapwood volume) than did the HTC treated samples. In terms of whole creosote however, retentions were not significantly different. Fuming was negligible immediately the PEC treated samples were removed from the pressure cylinder. In addition, the surface of freshly treated PEC samples was drier and much easier to handle than HTC treated samples and they remained dry even after eight months of weathering. 'Crud' formation on the surfaces of the exposed PEC samples was less than the corresponding HTC samples. There was no apparent difference in the penetration and macro-distribution of the two preservatives in the sapwood of matched samples. Full depth of sapwood penetration of both preservatives was visible.
C W Chin, J B Watkins, H Greaves


Accelerated termicidal performance data for new water-based copper linoleate formulations
1996 - IRG/WP 96-30104
An organic solvent based copper linoleate (Culin) has proved itself as an effective wood preservative in long term field trials in South Africa over a period of 30 years. Whilst the organic solvent based product offers good wood preservative performance, primary industrial interest has been in an emulsified version of the product. The objective of this study was to evaluate the influence of two different emulsifiers on the performance of emulsified versions of Culin against subterranean termites under accelerated field test conditions. The results indicated that the emulsions offered levels of protection that did not differ significantly from that of the original Culin formulation and CCA at equivalent copper retentions. However, variations in the performance of the products in the test indicated that the choice of emulsifier could influence the predictability of the products in the field.
D Conradie, P Turner


Protection of freshly felled timber against attack by bark boring insects
1981 - IRG/WP 1143
This report describes two experiments with the insecticide formulation Perigen, which contains the synthetic pyrethroid permethrin. At 0.2% w/v active ingredient individual logs were protected against bark boring beetles for 18 weeks. At 0.3% w/v active ingredients Perigen gave similar protection against insect attack to stacks of recently felled unbarked pine logs. This protection was at least equivalent to that obtained with a 5% w/v aqueous DDT emulsion.
J Dominik, P R Skidmore


A new preservative - A double-edged sword
1990 - IRG/WP 3573
Increasing environmental pressures on the use of pesticides throughout the world will impact more on the use of all wood preservatives. In particular the use of traditional wood preservatives and methods of application are under close scrutiny. The industry is responding to the challenge of developing alternative products and systems but faces great problems due to the excellent performance and safety record of traditional preservatives. Current research in preservation is aimed at producing more so-called "environmental friendly" preservatives. Developments to date have not produced alternatives which are as effective for long term performance and still have their own associated health and environmental hazards when compared to traditional products. The problems encountered in the introduction of new preservatives are illustrated by reference to case histories. The changes in standards and improvements in processing techniques for established preservative treatments are described. The need for effective handling and containment procedures to minimise risk with new as well as traditional preservatives is discussed.
M Connell, J A Cornfield, G R Williams


Influence of water-borne preservatives on water repellency and the impact of addition of water repellent additives
1992 - IRG/WP 92-3704
The primary goal of a desirable wood preservative system is to effectively control decay fungi and other biodeteriogens in service. The water repellent nature of a given system may play an important role in the protection of wood. In this study, the water repellency of several water-borne preservative systems has been evaluated by measurements of tangential swelling during immersion. The systems include cuprammonium formulations, such as ammoniacal copper carbonate (AC) and ammoniacal copper zinc arsenate (ACZA), ammoniacal copper quat systems (ACQ) and chromated copper arsenate (CCA). The influence of addition of water repellent emulsions into the above systems has also been examined.
L Jin, D M Roberts, A F Preston


The resistance of wood coated with different water-borne paints against colonisation by decay fungi
1996 - IRG/WP 96-10165
The susceptibility of wood painted with model paints of known composition to decay fungi was tested without previous weathering. Included in the study were five alkyd emulsion paints and five acrylic paints; one linseed oil paint and two solvent-borne alkyd paints. It was found that several components influenced the susceptibility of these paints. The results of the present study indicate that the particle size of latex paints, the pigment volume concentration and the amount and type of surfactant in the water-borne paints are critical for colonisation by decay fungi of painted wood. An anion surfactant was somewhat fungicidal. The results are briefly discussed in relation to major paint components and to available knowledge of the properties of water-borne coatings on wooden substrates. The present study is part of a larger project aiming at improvement of the durability of painted wood.
J Bjurman


The efficacy of commercial silicones against blue stain and mould fungi in wood
2008 - IRG/WP 08-30471
Scots pine (Pinus sylvestris L.) wood samples were vacuum pressure impregnated with quatsilicone micro emulsion (<40 nm particle size), aminosilicone macro emulsion (110 nm) and silicone macro emulsion with alkyl modified side groups (740 nm) and the resulting material properties were studied. Quatsilicone micro emulsion resulted in maximum bulking (4.8%) and anti-swelling efficiency (21.8%) in wood when treated with 30% concentration of silicone in treatment solution. All three chemicals made wood hydrophobic which was evident from capillary (longitudinal, tangential and radial) water uptake test adapted according to DIN 52617. Blue stain test EN 152 showed that aminosilicone macro emulsion (10% silicone in treatment solution) resulted in quite strong resistance to blue stain attack with both pre-weathered (1.2% staining of surface area) and not pre-weathered (0.2% staining of surface area) wood samples. Signs of blue staining were more evident on the pre-weathered samples which could be due to the break down of lignin, evident from the FTIR analysis. Blue stain development was evident by penetration of fungi through the ray cells visible in the cross sections of samples. Standard test for mould growth BS 3900 showed that wood treated with the aminosilicone macro emulsion (10% silicone in treatment solution) resulted in a delay and a certain degree of resistance to fungal growth on wood surfaces, whereas wood treated with the same concentration of quatsilicone micro emulsion and silicone macro emulsion with alkyl modified side group exhibited comparatively lower resistance.
S C Ghosh, C Mai, H Militz


Use of wax emulsions for upgrading of wood properties
2009 - IRG/WP 09-40451
Waxes are used for treatment of wood surfaces for several decades, predominately as surface treatments, because they did not penetrate into the wood. In order to overcome this issue, water emulsions were applied in present experiment. Five water emulsions of various concentration was used namely; two emulsions of montan wax (LGE, MW1), emulsion of polyethylene (WE1), emulsion of ethylene copolymer (WE3) and emulsion of oxidized polyethylene (WE6) wax. Performance of wax treated beech (Fagus sylvatica) and Norway spruce (Picea abies) against white rot (Trametes versicolor, Pleurotus ostreatus and Hypoxylon fragiforme) and brown rot fungi (Antrodia vaillantii, Serpula lacrymans and Gloeophyllum trabeum) were tested according to the EN 113 procedure, while EN 152-2 test was used for blue stain testing of Scots pine (Pinus sylvestris). In parallel, wood was impregnated with selected waxes and sorption properties were determined. The results showed, that impregnation of wood with waxes reduces water sorption. After one week of conditioning of wood at the 80% RH, moisture content of wax treated specimens was 50% lower than of control ones. Impregnation of the specimens with waxes improves their performance against wood decay fungi as well. Polyethylene (WE1) and oxidized polyethylene waxes (WE6) were found particularly efficient. However, this treatment does not improve resistance against blue stain fungi.
B Lesar, F Pohleven, M Humar


Wood Hydrophobic Modification by Mixed Wax Emulsions
2018 - IRG/WP 18-40839
An environmental-friendly, economical and facile method to construct hydrophobic system for improving wood repellency was applied in this study. Using paraffin wax and carnauba mixed wax O/W emulsions can simultaneously fabricate continuous wax films and rough structures in wood internal and external surface under appropriate heat treatment. In the study, single and mixed wax emulsions of 4% solid content were prepared for wood impregnation with subsequent heat treatment at 70oC. The water absorption, dimensional stability and contact angle of treated wood were determined, and the micromorphology of double-layer model was presented by Field Emission Scanning Electron Microscope (FE-SEM). Furthermore, the water distribution and water state were analyzed by Low Field Nuclear Magnetic Resonance (LF-NMR). The results indicate that micron-submicron rough structure and water-proof wax film could be both observed after demulsification and redistribution of mixed wax emulsions, which rendered wood hydrophobicity and long term water repellency.
C Chen, W Wang