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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

Durability of surface coating systems. Mycologg - an accelerated mycological test.
2004 - IRG/WP 04-20301
Field testing and natural aging/degradation of test sample, e.g. coated wooden surfaces is a slow process. Accelerated tests focus on mechanical properties, water uptake or sometimes stain fungi. Artificially weathered coated panels are not easily compared with naturally aged panels, and show the importance of involving the biological component among the degrading facors. It is a need for accelerated tests and especially tests that concider the interaction between the property of water uptake, weathering and biological factors. The Mycologg can combine artificial weathering, monitoring of moisture uptake and fungal growth.
L Ross Gobakken, J Mattsson, B Jacobsen, F G Evans

Blue stain in service on wood surface coatings. Part 1: The nutritional requirements of Aureobasidium pullulans
1992 - IRG/WP 92-1556
The nutritional requirements of Aureobasidium pullulans was examined with regard to nutrient sources that are potentially available in fresh and weathered wood. The study was designed to determine how far wood cell wall components need to be broken down during weathering before they provide a useful nutrient source for Aureobasidium pullulans. Various carbon sources were tested, with eight different isolates of Aureobasidium pullulans. It was found that the organism could utilise the simple sugars well, but not the oligosaccharides. The organism was also able to utilise well several lignin precursor compounds.
P R Sharpe, D J Dickinson

Comparison of colour change in wood clear-coating systems including inorganic and organic UV absorbers for exterior use
2010 - IRG/WP 10-40499
The aim of this work is to compare the performance of inorganic and organic UV absorbers used in a wood coating application against weathering. Our study has investigated the colour changes of selected UV absorbers; hombitec 402 RM from the Sachtleben Company as an inorganic UV absorber, tinuvin 477 DW from the Ciba Company as an organic UV absorber. The study was carried out on two wood species; Fagus sylvatica L., Pinus sylvestris L. The results obtained after 28 days (672h) of accelerated weathering showed that the colour stability was the same for hombitec 402 RM and tinuvin 477 DW and both systems showed a significant improvement of colour stabilization compared to the control samples. In addition, the wood surface from cracks was protected with the clear-coat containing both of UV absorber.
Ö Özgenç, B Forsthuber, A Teischinger, C Hansmann

Moisture protection and performance during 5 years exposure of 19 wood coating systems on a cladding in Vienna
2011 - IRG/WP 11-40561
A cladding with vertical boards of Norway spruce (Picea abies) comprising different coating systems had been exposed to natural weathering oriented south west in Vienna for 5 years. Weathering behaviour of the boards was assessed in intervals and wood moisture content was measured over the first 22 months of exposure. The moisture protective properties of the coating systems were assessed using laboratory methods. The results of weathering behaviour indicated higher coating durability with higher dry film thickness and lower transparency of the coating systems. The coating systems provided a certain degree of moisture protection that was influenced by paint colour, water permeability and surface roughness. Panels with low permeable coatings showed a better performance in natural weathering.
G Grüll, I Spitaler, M Truskaller

Comparison of exterior performance of two coating systems based polyurethane applied Pinus sylvestris L. and Picea orientalis L. wood
2012 - IRG/WP 12-40588
Some surface changes in sapwood and heartwood of two species before applying clear-coating were characterized after accelerated weathering time. Wood specimens covered with two types polyurethane (PU) films were also observed in accelerated weathering exposure. In this study, changes on the wood surface were compared of between wood specimens covered with two types polyurethane (PU) films after irradiation. The study was carried out on sapwoods and heartwoods two wood species; Fagus sylvatica L., Pinus sylvestris L. The artificial weathering experiment was performed by cycles of 2 hours UV-light irradiation followed by water spray for 18 minutes according to ASTM G 53-96. The surface changes of the weathered sapwood and heartwood samples applied clear-coating were characterized by surface roughness and color measurements. Color measurements were made by a with a Konica Minolta CM-600d (Canada) at several intervals (0-24-72-168-240-336-408-504-600-672 hours) in artificial weathering of treated and untreated wood. Additionally surface roughness was measured on the surface of all wood samples, unweathered and after 672 hours of weathering by a Mitutoyo Surfest SJ-301 instrument. According to the results, the scots pine and spruce sapwood samples provided better protection color changes than the scots pine and spruce heartwood samples showed lower color changes. The highest increasing surface roughness values were on the wood samples applied 2.system clear-coating (Y) by reason of the wood surfaces contain several checks, splits and cracks caused by weathering. The wood surface applied 1.system clear-coating (X) showed that no high cracks and substantially surface properties changes were observed significantly due to weathering.
Ö Özgenç, Û Cafer Yıldız

The Comparison of Weathering Resistance of New Generation Wood-Coating Systems
2017 - IRG/WP 17-40789
In this study, the performance of wood-coating systems containing different UV absorbers was evaluated in artificial weathering conditions. Acrylic-based resin containing three different UV absorbers was applied on oriental beech and scots pine surfaces. Weathering conditions were sustained for 84 days. After the weathering test, the change of color and roughness on the wood surface was measured to determine the effectiveness of coating systems. The coating systems were found quite resistant against weathering conditions. The color changes of wood samples were lower compared to the beginning of the weathering test. Similarly, the changes in surface roughness values of wood samples showed that coating systems provide quite high preservation against weathering conditions.
Ö Özgenç, S Durmaz

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

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

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

Field performance of wood preservative systems in secondary timber species
1997 - IRG/WP 97-30152
The objective of this ongoing study is to evaluate the performance of new, potential, and standard wood preservative systems in secondary North American timber species. Eleven preservative systems were evaluated in this study - ACQ Type B, Copper Citrate 2: l, CDDC, chlorothalonil/chlorpyrifos, copper-8-quinolinolate, tebuconazole/chlorpyrifos, RH287, propiconazole/chlorpyrifos, copper naphthenate, CCA. and creosote. Field evaluations are being performed with ground contact field stakes and termite-specific testing in Hawaii, along with laboratory soil bed tests. The major wood species used with all the systems and evaluation methodologies are loblolly pine, northern red oak, tulip poplar, and cottonwood. More limited evaluations (field stakes only) are being conducted with eastern hemlock, red maple, and sweetgum. Information is presented from laboratory soil bed, field termite, and field stake evaluations. There is good correspondence between soil bed and field stake results. The more highly developed preservative systems and those in an AWPA P9 Type A oil carrier tend to perform better, and there can be a strong affect on performance from the wood species.
P E Laks, K W Gutting, R C De Groot

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

Blue stain in timber in service. Results of co-operative tests to compare different artificial weathering systems 1981-82
1983 - IRG/WP 2193
The paper describes results of the third phase of co-operative laboratory experiments comparing the effects of different artificial weathering systems on chemicals to control blue-stain in service. Atlas, Xenotest and Marr equipments are shown to give essentially the same results for 5 of the 6 chemicals tested.
A F Bravery, D J Dickinson

Safety technique in wood preservation
1974 - IRG/WP 54
S N Gorshin, I G Krapivina, B I Telryatnikova

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

Natural Durability Classification Systems Used Around the World
2009 - IRG/WP 09-10694
Around the world natural durability is classified in different ways. The nature and rigor of the tests used to measure durability, the method of classification based on these data, and use of these classifications to specify end uses or predict service life all vary. This can lead to confusion among people not familiar with the various systems used. This review describes the methods used to classify naturally durable wood around the world.
R Stirling

Physical barriers and bait toxicants: The Romeo and Juliet of future termite control
1991 - IRG/WP 1503
Soil chemical barriers are considered by some to be the most important technique for protecting buildings against subterranean termites in Australia (and elsewhere), providing a barrier against termite penetration. However, there is no such thing as a barrier that is 100 per cent +protective. And given the worldwide problems of using organochlorine termiticides, public awareness of chemical pollution and contamination to the environment, emphasis on physical barriers has been refocussed. In the event of such barriers being penetrated, the use of suitable bait systems and toxicants is considered a fruitful "back-up" strategy in future termite control measures. Such a system is environmentally friendly, has wide public acceptance, and readily marketable.
J R J French

Evidence supporting the use of termite baiting systems for long-term structural protection
2000 - IRG/WP 00-10377
The efficacy of the Sentricon Colony Elimination System containing Recruit II termite bait (0.5% hexaflumuron) in controlling active subterranean termite infestations has been demonstrated in numerous studies. This baiting system and other termite baiting systems are now widely used, and generally accepted, tools for remedial termite control in North America, Hawaii, and other parts of the world. The role of baiting systems in prevention of termite damages and long-term structural protection, however, is more controversial than their use in remedial control. We discuss three lines of evidence in support of the use of baits for long-term structural protection: (1) successful control of termite populations with baits in remedial studies allows a conceptual leap to preventative efficacy, since baits target colonies and populations and cannot be evaluated directly for prevention in the manner of soil insecticide barriers; (2) field and laboratory studies demonstrate that termite colonies feed on multiple resources and continue to radiate outward from each of those resources in search of additional food, increasing the likelihood of rapid bait discovery; and (3) results of our long-term field studies over the past decade demonstrate that newly invading termites will reuse existing galleries in the soil left by earlier colonies that lead to monitoring stations, were detected in monitoring stations, and were subsequently eliminated without any noticeable evidence of structural infestation or damage.
J K Grace, N-Y Su

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

Evaluation of Barrier Wrap Systems after 71 Months of Exposure
2013 - IRG/WP 13-40631
A 71 month study of the performance of booted samples in ground contact was conducted in AWPA hazard zone 4. Data indicated that excellent performance of wrapped systems, even over untreated wood, could be obtained. Instances of decay colonization or termite attack could all be attributed to some breaking of the integrity of the barrier system. Good performance for treatment below ground contact threshold was demonstrated.
H M Barnes, M G Sanders, G B Lindsey, C McIntyre

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

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