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Influence of hydrophobic agents on the leachability of boron
1995 - IRG/WP 95-30064
Besides its low mammalian toxicity and a broad range of activity towards both fungi and insects, boron shows a high diffusibility, encouraging it to treat wood species of low permeability. However, its difussibility is at the same time responsible for a high risk of leaching, known since long. Nevertheless quantitative data about this process are only rarely available. Therefore, the leaching of boron under different conditions and possible means of hydrophobising boron treated wood in order to reduce leaching were investigated by laboratory and field tests. For this purpose paraffin and a primer have been applied to protect the inner surface and alkyd-resin and a varnish as surface coat. The results demonstrate that boron diffuses even at moisture contents below 20%. Thus leaching can not be affected by hydrophobic agents placed on the inner surface of wood because diffusion still takes place within the cell-wall. Surface coatings have some protective effect but only during a distinct periode which is depending on the thickness of the coat. With time leaching increases with increasing moisture content underneath this coat. The best way to prevent leaching is the logistical protection by storing and using boron-treated wood exclusively under cover. Only for a short periode, for example during construction, a surface protection with waxes or resins will be effective.
A Peylo, H Willeitner


Algal growth resistance of paints for coating of wood; a laboratory study
1997 - IRG/WP 97-10213
Twelve paints were tested for resistance against algae. In addition, one algicidal compound commercially used for remedial treatments of algal growth on paints was tested for its effectiveness for prevention of algal growth. An agar diffusion bioassay was employed in which paint films on filter paper discs were placed on mineral salt medium and sprayed with an algal suspension containing a mixture of one blue-green alga, Oscillatoria tenuis, and two green algae, Ankistrodesmus gracilis and Pleurococcus sp. Most growth was recorded in plates with discs painted with acrylic paints. Two acrylic paints containing a commercial fungicide at normal or double concentration permitted the same amount of growth as the same acrylic paint without fungicide addition. The solvent-borne alkyd paints and the alkyd emulsion paints were more inhibitory against growth of algae. Only some of the acrylic paints permitted any growth of the green alga Ankistrodesmus gracilis. Acrylic paints containing a commercial algicide inhibited the growth of the Pleurococcus sp. and Ankistrodesmus gracilis but permitted some growth of Oscillatoria on the agar medium used.
J Bjurman


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


Silicon compounds as additives improving alkyd-based wood coatings performance
2010 - IRG/WP 10-40531
The reactivity of cellulose with solvent-born alkyd-based wood coatings supplemented with organosilanes was analyzed. Structural analysis of cellulose subjected to the reaction with organosilanes and following extraction with water was performed using Fourier-transform infrared spectroscopy (FTIR). The analyzed IR spectra comprise bands 1250 cm-1 typical for the SiC group and 800 cm-1 typical for vibrations of SiC and/or SiO groups. The presence of these bands in the spectra proves the occurrence of a reaction between cellulose and organosilanes. Silicon concentration in cellulose was determined by AAS after the reaction with coating system after leaching.
B Mazela, I Ratajczak, K Wichłacz-Szentner, P Hochmańska


Management of the wood and additives wastes in the wood processing industries: Problematics and technical answers review
1996 - IRG/WP 96-50073
Management pathways for pure wood subproducts are well known and used; but as soon as additives like preservatives, glues, varnishes or coatings are present within the wood wastes, their disposal or valorization becomes more tricky. The different kinds of mixed wood wastes of the wood processing industries, from the sawmill to the furniture manufacture, are identified herewith and their diversity is examined. These wastes can be classified according to their danger characteristics, taking into account the type of additives, their concentration, their availability for the environment, the physical state of the waste. Different disposal pathways are then considered. Combustion, with the possibility of energetic valorization seems the best answer for a major part of these wastes. But this is only possible if good combustion conditions are defined, so that no harmful products are emitted. Moreover, these conditions must be affordable on the technical and economical point of view. Then, some wastes cannot be burned in such a simple way, and need a larger approach, which is presented in this document.
S Mouras, G Labat, G Deroubaix


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


Summary of development of pile wrappings in Los Angeles Harbour
1987 - IRG/WP 4141
G Horeczko


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


Principles and procedure of the planeing test
1981 - IRG/WP 2162
Small end-sealed samples of pine-sapwood (1.5 x 2.5 x 5 cm³) are treated by brushing and afterwards different parts of the treated surface are removed. The remaining part of the sample is tested against either insects or fungi. If no attack occurs sufficient amounts of biocides have been penetrated at least beyond the zone which has been removed. In spite of some problems the test seems the only suitable method, to evaluate organic solvent preservatives, mainly those containing resins, for simple treating methods.
H Willeitner, M Gersonde


Blue stain in service on wood surface coatings. Part 2: The ability of Aureobasidium pullulans to penetrate wood surface coatings
1992 - IRG/WP 92-1557
The ability of Aureobasidium pullulans to penetrate seven different wood surface coatings was examined. Eight isolates of Aureobasidium pullulans were used. Following penetration, light microscopy was used to examine the effect of the fungus upon the coating, and growth at the wood-film interface. The fungus showed different growth capabilities with different types of surface coatings. Some isolates were able to penetrate alkyd based coatings, but were unable to grow in the film. In contrast, after penetration through latex based coatings several isolates were able to produce growth in the films themselves.
P R Sharpe, D J Dickinson


Surface coatings for impregnated wood
1992 - IRG/WP 92-3684
The use of proper surface coatings enhances the aesthetic and protective properties of impregnated wood. Good results with especially water-borne coatings have been obtained for class-A impregnated L-joints and claddings in field tests started in 1982.
L Kotama


Factors affecting leaching of preservatives in practice
1978 - IRG/WP 3113
At the 7th Meeting of the IRG in Poland in May 1975, the findings of collaborative laboratory leaching techniques were discussed, and the dangers inherent in using such results to predict the behaviour of preservative-treated components in service were emphasised. In order to improve our understanding of the factors governing leaching of preservatives in practice, and to identify areas where further research is required, it was agreed that a literature review should be prepared. This is presented below. Some points may be made regarding its format and content. First, the review shows that a large number of factors are of importance, including the properties of the wood, the leach water, the preservative and method of application and the nature of the environment to which the product is exposed. In many situations these factors interact and it is clearly impossible within the scope of this short paper to discuss all aspects of the problem in detail. However, the compilation of references will give ready access to the literature on particular topics. For ease of collation, the findings are discussed under a number of different headings. Secondly, less than one-third of the references cited deal with the results of service or field trials, while the others describe laboratory experiments designed to provide comparative data. The reservations expressed above concerning such small-scale experiments must be borne in mind when considering the validity of these findings. The information available on this topic up till 1964 was comprehensively reviewed by Wallace who identified and commented upon many of the factors discussed below. Her paper contained discussion on the performance of individual preservatives and on the mechanism of their fixation within the wood. These topics will not be considered here in any detail except insofar as they reflect general trends.
R Cockcroft, R A Laidlaw


Analysis of organotin fungicides in wood preservative solutions and double-vacuum treated wood
1983 - IRG/WP 3250
A new analytical method using high-performance thin-layer chromatography (HPTLC), for the assay of organotin compounds in preservative-treated wood, is presented. The organotin compounds are extracted from the ground wood sample with a mixture of hydrochloric acid and ethanol. After HPTLC-separation, exposure of the thin-layer plate to ultraviolet light, and dipping of the plate into a 0.1% pyrocatechol-violet solution, the different organotin compounds are quantitated using a scanning densitometer.
W Hintze, S V Ohlsson


Surface Barriers for Protection of Culture and Heritage Wooden Objects from Insect Attack
2004 - IRG/WP 04-40286
Anoxic treatment is an environment friendly procedure for eradication of wood boring insects in wooden objects of cultural and historical heritage. However, after the anoxic treatment, wooden antiques remain susceptible to further insect attacks. Possible protection against insects could be provided by the so-called post-repression protective barriers. Potential coating materials for such barriers to be used on hidden unpainted surfaces of wooden antiques were investigated. We studied relevant properties of five different coating materials: thickness, hardness by resistance to scratching, adhesion, flexibility, resistance to temperature changes, conformability to the concept of reversibility and bioresistance against wood boring insects. The most promising results were exhibited by the coating that is commercially used for protection of fresh log ends in forests, immediately after a tree is cut.
M Petric, M Pavlic, B Kricej, M Humar, F Pohleven


Practical testing of wood preservatives to prevent weathering damage and infection by micro-organisms on spruce and pine
1989 - IRG/WP 3530
Brush application, is generally used to prevent wooden window frames from decay caused by influence of weathering and fungi. Accordingly 10 boards of pine (Pinus sylvestris) and spruce (Picea abies) were treated with 10 commercially used wood preservatives. The efficiency of fungicides by using chiptest and blue stain test (EN 152), the effectiveness against weathering as well as the course of colonization of microfungi were measured on boards, that had been hurted by sawing. Results after one year's exposure showed that neither the normally required amount of 250 ml/m² nor the effective depth of penetration of the fungizidal equipment had been realized by using brush application. The smaller the permeability of the coating system, the more likely ideal conditions for the growth of fungi (e.g. basidiomycetes) are provided, answering hurtings of the coating and moisture contents of more than 30%. The variety of fungi (on pine 32 and on spruce 17 species) can be a result of anatomical differences and distinguished compounds of the wood species. After 24, respectively 36 weeks of exposure the frequent occurrance of basidiomycetous yeasts (Cryptococcus albidus, Rhodotorula mucilaginosa), blue stain fungi (Aureobasidium pullulans, Hormonema dematioides), Epicoccum nigrum, Alternaria alternata and Phoma species was noted.
R Gründlinger, O Janotta, H Melzer, K Messner


The efficacy of polyurethane coatings on wood samples exposed in the marine environment. Final Report -10 Year Assessment
1996 - IRG/WP 96-10170
The results of an IRG collaborative marine trial to investigate the long-term permanence and efficacy of polyurethane coatings against marine borers are reported. PU-coated wood samples were exposed at a range of sites from tropical to cold temperate locations. The marine borer species present at the sites included teredinids, pholads, limnoriids and sphaeromatids so that each site offered its own peculiar degree of hazard. At most sites the integrity of the PU-coating was sound and wood samples were undamaged by marine borers after periods of exposure extending up to ca. 10 years. Where damage to the wood was recorded, mechanical abrasion of the coating had exposed the wood to attack by teredinids and pholads at one site and at a second site, sphaeromatids had perforated the coating. The significance of the results is discussed in terms of the protection afforded to submerged maritime timber structures coated with elastomeric polyurethane.
R A Eaton


How to keep coated wood structures sufficiently dry to avoid damage caused by rot
1991 - IRG/WP 2376
During the last ten years, a new type of problems with wood rot has emerged in Scandinavia. Thousands of houses have been damaged by wood rot attaching to the exterior wood panel. This paper provides an overview of finished and ongoing work in order to identify the cause of these problems. In field tests, the moisture conditions were measured in panels coated with different paint systems. The influence of the panel structure and end-grain sealing on the moisture balance was also studied. The results from these tests show a large difference in the moisture balance between panels with different exterior wood coatings. In laboratory tests, the transmission of water vapour through paint films was measured using a modified cup method, which provides more realistic conditions for coated wood than the common cup method. One interesting observation made in the studies reported here is that latex paints seem to be much more permeable at high levels of relative humidity than earlier research has shown.
S Hjort


Influence of a dipping preservative treatment on the performance of wood finished with waterborne coatings
1998 - IRG/WP 98-40121
Within a larger European research project on the performance of joinery finished with waterborne coatings, the influence of a water based dipping preservative treatment was studied in several ways. Six different waterborne coatings were tested with and without a preservative underneath the coating. The performance was tested on pine sapwood and spruce panels in a 2-year outdoor weathering trial on two different sites in Europe. The panels were evaluated visually with respect to cracking, flaking, surface mould growth and development of blue stain underneath the coating. In several cases the preservative treatment improved the performance of the coating, not only with respect to biological deterioration but also for cracking and flaking of the paint. A limited number of coatings were also tested on L-joints according to the EN-330 and of national dutch design. The EN-330 L-joints appeared to be a more challenging substrate compared to the national type, which had a glued connection between tenon and mortise. The influence of the preservative on the moisture content of the wood was evaluated by monthly weighing of the samples exposed outdoors and by laboratory measurements of the coating permeability. At least in laboratory trials the dipping treatment caused a slight reduction of the water permeability. This is most likely the result of the polymeric binder material present in the preservative. The presence of polymeric material underneath the coating was also confirmed in a microscopic evaluation of the distribution of the dipping preservative. The preservative was not equally distributed in the wood, but showed a clear preference for the ray-tissue.
M De Meijer, J Creemers, W Cobben, P Ahola


Durability of surface preserved wood particle boards submitted to atmospherical influence
1995 - IRG/WP 95-40039
The worldwide problem of the continuously growing deficit of high quality natural wood material has caused the attempts of many research workers to find effective composites such as wood particle boards (WPBs) for replacing the massive wood for constructive purposes, depending on where the boards are exploited - in the open or under a shed, they are submitted to various climatic factors such as heating, drying, moistening, frosting, irradiation, that's why for reaching high atmospheric resistance, it is very important, a durable protection of the WPBs with suitable coatings against the atmospheric influence to be ensured.
L Valcheva


Surface Barriers for Protection of Culture and Heritage Wooden Objects from Insect Attack
2004 - IRG/WP 04-20286
Anoxic treatment is an environment friendly procedure for eradication of wood boring insects in wooden objects of cultural and historical heritage. However, after the anoxic treatment, wooden antiques remain susceptible to further insect attacks. Possible protection against insects could be provided by the so-called post-repression protective barriers. Potential coating materials for such barriers to be used on hidden unpainted surfaces of wooden antiques were investigated. We studied relevant properties of five different coating materials: thickness, hardness by resistance to scratching, adhesion, flexibility, resistance to temperature changes, conformability to the concept of reversibility and bioresistance against wood boring insects. The most promising results were exhibited by the coating that is commercially used for protection of fresh log ends in forests, immediately after a tree is cut.
M Petric, M Pavlic, B Kricej, M Humar, F Pohleven


A collaborative test to determine the efficacy of polyurethane coatings on wood samples in the marine environment. 2nd Interim Report
1990 - IRG/WP 4161
The results of a collaborative international test to evaluate the performance of elastomeric polyurethane coatings of wooden test samples exposed in seawater at 13 sites around the world are reported. The samples have been exposed at sites with known infestations by molluscan and/or crustacean wood borers. Performance data for up to 4 years exposure at some sites is presented providing information on the soundness and adherence of the coatings to wood and the degree of surface fouling. To date, all samples coated with polyurethane remain unattacked by marine borers.
R A Eaton


Observations on the activities of Sphaeroma in Australia
1994 - IRG/WP 94-10059
Polyurethane coated timber specimens are being attacked at Townsville by Sphaeroma terebrans in the tidal zone. To understand this marine borer better, the results from several other marine tests at Townsville are briefly described, and information about Sphaeroma spp. from elsewhere in Australia is presented. At Townsville, Sphaeroma seems to prefer the shady side of timber fender piles. Also, it is rarely found below the tidal zone. After two years, CCA-treated slash pine mooring piles were lightly attacked, and after 5.7-8 years eight double-treated eucalypt fender piles were only lightly attacked, while three were moderately attacked in the tidal zone. Untreated turpentine piles last about 10-16 years in Townsville, due to the damage caused by Sphaeroma. At nearby Bowen, Sphaeroma terebrans in two experimental piles died after the piles were pulled from the sea, and took more than 3 years to recolonise the piles after they were reinstalled. During this time after reinstallation, the original Sphaeroma terebrans holes were inhabited by Sphaeroma walkeri, a non-wood borer. At a brackish water test site at Port Stephens, Sphaeroma is more often found below low tide. It also prefers to bore upwards rather than downwards, perhaps to lessen the amount of silt entering its burrow. In the southern state of Victoria, Sphaeroma is not an economic problem, causing only minor etches and few holes. There in the tidal zone, it can scallop out disused longicorn beetle emergence holes to give an unusual pattern of attack on the pile surface.
L J Cookson


Blue Stain Testing of Alkyd and Acrylic Stains
2003 - IRG/WP 03-20273
Resistance against blue stain of semi-transparent alkyd and acrylic stains was tested by both EN 152 and the so-called reverse exposure test methods. Comparison of the results, obtained by both methods was the most important aim of this study. As expected, performance of the water-borne acrylic paint was lower compared to protective effectiveness of the alkyd stain. This difference was even more pronounced when artificially accelerated aged samples were exposed. It seems that the reverse exposure method may give more distinctive results. In general, our results confirm previous literature reports on adequacy of the reverse test method for evaluation of blue stain resistance of surface finishes.
M Petric, M Pavlic, B Kricej, M Humar, F Pohleven


The practice of using concrete on wood piling for marine use in Thailand
1982 - IRG/WP 492
The practice of using concrete on wooden poles has been carried on in Thailand for a long time in pile-houses and pier constructions which have been situated in, or partly in the sea. In such instances, the hewed round and/or square-sawn heartwood poles of naturally durable timber species have been coated with concrete of about 5 to 10 cm or more in thickness, and to about 100 cm above the highest tide level. Very durable species such as Xylia kerrii Craib & Hutch., Shorea obtusa Wall., Pentacme suavis A.DC., Hopea odorata Roxb., and Pterocarpus macrocarpus Kurz were used for such poles. They were well air-dried before the application and coated with a special mixture of concrete, which consisted of sand, crushed lime and stone, and cement powder which was used 1-2 times more than the concrete mixture used for general masonry. The performance of these poles treated in this way, as far as could be ascertained from the users, is about 15 to 20 years, or even more in some instances. Unfortunately it has not been possible to obtain exact data on the service life of these concrete-coated poles. Also palm trees have been used in sea-water without any treatment. The palm trees that have been used are Livistona saribus Herr., and Livistona speciesa Kurz. These have been used as piling for anchoring fishing boats to, because of their high elasticity and also as piles for supporting piers. They have given performances of more than 10 years of service. The outer parts of these trees are very strong and naturally durable to marine borer attack, but the inner parts of them are not resistant to decay fungi, although even though their inner parts have become rotted, they have remained strong enough for the above-mentioned purposes of utilization. If these palm trees are treated with suitable preservatives before being put into use, in order to protect them against the decay fungi, their service lives are much greater than those of untreated palms.
B Anuwongse


The degradation of wood by metal fastenings and fittings
1972 - IRG/WP 302
As well as the hazards of biological decay, timber used in boat building is subject to the effects of chemical decay associated with the corrosion of metallic fastenings. The title has been deliberately chosen to emphasize that in wooden construction the troubles are not just those of corrosion of the fastenings, but also the destructive secondary effects on the wood caused by the products of the corrosion processes (Plate I). For centuries the world has lived with these troubles commonly referred to as "nail sickness". In contrast to biological decay the chemical decay associated with corrosion is confined to the wood adjacent to corroded fastenings and it is regrettable that in repair work so much wood has to be replaced because of a small percentage degrade in vital spots. Before methods can be devised to overcome these troubles, it is necessary that a better understanding is reached of the mechanisms operating in the degradation process, and recent work at FPRL has thrown some light in this area. The general problem will now be considered in some detail followed by suggestions on possible preventative and remedial measures. Corrosion is the result of an electrochemical process in which the corrosive effect is proportional to the current which flows between areas of potential difference. There are a number of causes of this electrochemical effect such as dissimilar metals in contact, differences in concentration of some chemical factor such as the electrolyte or oxygen availability, stress etc. In all cases areas of different polarity are produced and corrosion only proceeds when the electrical circuit is completed by an electrolyte bridge eg sea water, and a conductor between the anodic and cathodic areas. Figure 1 shows a simple diagram of electrochemical corrosion.
L C Pinion


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