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Susceptibility of painted wood to discolouring fungi - influence of binder, solvent and surfactant
1992 - IRG/WP 92-3714
Previous studies have shown that the basic composition of paints, without fungicide addition, can significantly contribute to the varying microbial susceptibility of painted wood. Previously, non-weathered water-borne acrylic paints applied to wood without a primer were shown to be more susceptible to mould attack than solvent-borne alkyd paints. The present study was initiated to reveal if this difference was mainly an effect of the type of binder, solvent or surfactant used. Laboratory made paints, including water-borne acrylic paints, a solvent-borne acrylic paint, a solvent borne alkyd paint and alkyd emulsion paints, with known compositions were tested. It was found that the type of binder was more important than the solvent. The use of different surfactants could lead to different susceptibility of alkyd emulsion paints on wood.
J Bjurman, C Herder

Growth and succession of mould on commercial paint systems in two field sites
2007 - IRG/WP 07-30421
Discolouring fungi reduce the service life of coated wooden claddings in façades and increase the total cost of ownership due to shorter maintenance intervals. It is of major importance to find paint systems for wood which are durable and have a high resistance to mould growth. A total of 15 paint systems from 9 different manufacturers were exposed on two field sites, Sørkedalen and Birkenes, in Norway. Finishes included in the study were water-borne and solvent-borne alkyd primers, water-borne mixed alkyd/acrylic paints, water-borne alkyd paints, water-borne acrylic paints and solvent-borne alkyd paints in different combinations. Untreated spruce was used as a control. The panels were exposed outdoors for 16 months and the degree of mould growth was estimated by visual inspection every second month except during winter time. The outdoor test procedure was based on EN 927-3. Temperature, precipitation and relative humidity data were collected on each site. The paint systems had the same mould growth performance in both test sites after 16 months. Although average temperature and precipitation were higher in Birkenes, the mould infestation appeared faster in Sørkedalen which had a higher average RH. Pure water-borne systems performed best in terms of the degree of mould growth and systems with a solvent-borne alkyd top coat performed poorest. The paint systems with lowest degree of mould growth had IPBC as the only fungicide in the top coat and a mixture of several fungicides in the primer. With few exceptions, paint systems with an alkyd top coat, either solvent-borne or water-borne, have higher degree of mould growth than acrylic and mixed alkyd/acrylic top coats.
L Ross Gobakken, K M Jenssen

Assessment of mould growth on coated wood - methods and application
2009 - IRG/WP 09-20423
Discolouring fungi reduce the service life of coated wooden claddings in façades and increase the total cost of ownership due to shorter maintenance intervals. The project “Enhanced service life on coated wooden facades” has as its main objective to develop new methods for early prediction of durability and longer aesthetic service life of coated wooden cladding related to consumer needs and new building and environmental regulations. Different methods for mould growth assessment on the surface of coated wood exposed outdoors will be looked in to and Quantitative Real-Time Polymerase Chain Reaction (QRT-PCR) and Fourier Transform Infrared Spectroscopy (FTIR) will be developed as tools for objective quantification. In this paper four methods for assessment of mould growth on the surface of coated wood are presented; visual assessment, digital image analysis, QRT-PCR and FTIR, and the application of the different methods are discussed. Further, a comparative study was done using visual assessment and digital image analysis when measuring mould growth coverage on coated wood. 7 coatings with different typology and fungicide were tested according to EN927-3 outdoors for 2 years at Sogn test station, Oslo, Norway. Results obtained from visual assessment by using the rating scale in EN927-3 and a chosen algorithm for digital image processing was compared and the methods showed conformity. Alkyd modified acrylic coatings were found to perform significantly better than pure acrylic and modified alkyd coatings.
L Ross Gobakken, C M Whist, O Høibø, P J Hovde, E Larnøy

System treatments of Pinus sylvestris - influence on moisture, decay and discoloration
2013 - IRG/WP 13-30612
Biological activity can cause challenges for the use of wood in outdoor exposure. Decay and discolouring fungi influence the service life of wooden constructions, and the moisture content of the wood is often an important factor. The aim of this study was to evaluate the performance of different combinations of preservative/modified wood protection treatments and surface treatments for wooden decks in different exposure situations after ten years of field testing. Fourteen different wood protection treatments were tested, in addition to Scots pine sapwood, Scots pine heartwood and European larch heartwood. Furthermore two different surface treatments were included (alkyd oil with iron oxide pigments (AO) and alkyd emulsion without pigments (AE)) in addition to no surface treatment. The test setup used was the “Stapelbädds metoden”. The bottom layer is in soil contact and this stack method provides a moisture gradient within the five layers included. As expected a gradient of increasing wood moisture content and fungal decay rating was found from the top layer to the bottom layer of the stack. For samples with no surface treatment the treatments with lowest wood moisture content was Styren, Tanalith E7, Royal with pigment, European larch heartwood and thermal modification. In the stacks without surface treatment Royal with pigment and Gori SC 100 were the only treatments with decay rating ≤ 1 in all layers, while Scots pine sapwood, Scots pine heartwood and UltraWood all had decay ratings > 2 in all layers. AE surface treatment decreased fungal decay in all layers for furfurylation, Scots pine heartwood and Tanalith M. A similar trend including all layers was not found for AO. All treatments were totally covered by discolouring fungi with the exceptions of ACQ 1900 and Scanimp. Among the untreated samples European larch heartwood generally gave the best performance. The results show that moisture content and fungal decay rate can be reduced with the support of a surface treatment, but they also showed that the opposite can also be the case after ten years of field exposure.
A Schabacker, G Alfredsen, L Ross Gobakken, H Militz, P O Flæte

Performance of kiln-dried and air-dried anti-sapstain treated pallet timber under use scenarios against wood discolouring fungi
2015 - IRG/WP 30669
During their lifespan there is a high probability that wooden pallets and packaging material will be exposed to rainfall or rewetting conditions, increasing the risk of growth of discolouring fungi. Kiln-drying of wooden pallets and packaging material without anti-sapstain treatment does not give efficient protection against wood discolouring fungi during rewetting periods. However additional temporary protection can be achieved, when pallets and packaging material are manufactured from timber treated with anti-sapstain preservatives. In order to compare the performance of kiln-dried pallets and air-dried pallets treated with an anti-sapstain preservative against blue-stain and mould infestation, three practical use scenarios of rewetting were investigated. The first scenario was the simulation of rainfall, followed by indoor storage under moist and warm conditions representing shipping of wet pallets in closed trucks or container. The second scenario simulates storage of humid goods or goods which can release moisture like, e.g., fruits or vegetables which have been stored under plastic foil in a changing temperature climate like e.g. during night and day. Condensed water can be formed on the foil building water droplets which will increase the wood moisture. The third scenario was the simulation of pallet movement of cooled goods from a cold storage warehouse into humid and warm climate area, studying the influence of the condensed water on the surface of a pre-cooled good, packed with foil on the pallet and subsequently stored or transported under high humidity and elevated temperature. The evaluation of the specimens was carried out by optical assessment according to CEN/TS 15082. After 28 days in all of the simulated scenarios the kiln-dried pallets were three times more affected by moulds and sapstain fungi than the pallets treated with anti-sapstain preservatives.
A Steitz, E Stoyanova, N Pfabigan, R Gründlinger

Bio-friendly wood protection systems - resistance to mould and blue-stain fungi
2017 - IRG/WP 17-30713
With stricter restrictions on the use of biocides and increasing environmental awareness there is a pronounced need for effective bio-friendly protection systems in the wood preservative and wood coating industry. One of the possible pathways is to exploit and utilize natural substances with active biological effects. Silanes, caffeine, natural oils and potassium carbonate were chosen as compounds in 16 different formulations intended as wood protection systems. The aim of this study was to test the resistance of the selected protection systems against mould growth and growth of blue-stain fungi. Combination of caffeine and amino functional silanes showed good resistance towards blue-stain fungi when applied to pine and the same was found for the combination of linseed oil and amino functional silanes. Some indications of resistance towards mould fungi were also detected for the same chemical combinations.
L Ross Gobakken, W Perdoch, B Mazela, P Kwaśniewska-Sip, G Cofta

Which fungi cause sapstain in Canadian softwoods?
1998 - IRG/WP 98-10285
The Canadian forest products industry suffers considerable losses in revenue due to fungal stains. There is an increased awareness that more complete knowledge about the causal organisms might help solve the problem. A first step was to initiate a thorough survey of bluestain fungi in Canada. Systematic sampling was done at seven selected sawmills in six Canadian provinces. In summer 1997 fresh logs and lumber were set aside a month prior to sampling for fungi. Five commercially important softwoods, Abies balsamea, Picea mariana, P. glauca, Pinus contorta and P. banksiana were included in the studies. The objectives were to identify the main discoloring fungi and subsequently to evaluate the genetic diversity among isolates of the fungal species found to predominate. Fungi isolated from the experimental timber were identified based on their morphological characteristics, measurement of their growth rates, and by testing their mating compatibility with known mating types. A substantial number of isolates and a variety of species were obtained. Most frequently isolated were species from the genus Ophiostoma. A more diverse range of fungi was found in logs than on lumber. Preliminary data suggest that some species tend to predominate on certain wood species and in certain geographic regions but none appeared to be exclusive.
A Uzunovic, Dian-Qing Yang, P Gagné, C Breuil, L Bernier, A Byrne

Effect of acetylation on decay resistance of wood against brown-rot, white-rot and soft-rot fungi
1989 - IRG/WP 3540
Effect of acetylation on decay resistance of wood was investigated using wood blocks of Cryptomeria japonica, Pinus densiflora, Albizia falcata and Fagus crenata. Blocks were treated with uncatalyzed acetic anhydride for different lengths of time and exposed to Tyromyces palustris, Serpula lacrymans, Coriolus versicolor and unsterilized soil. The action of OH-radical on acetylated wood was also examined using Fenton's reagent. The enhancement of decay resistance by acetylation was revealed clearly for all cases of exposures but varying with fungal and wood species used. For a brown-rot fungus Tyromyces palustris, the weight loss reached almost nil in all woods at 20 WPG (weight percent gain) of acetylation, after the striking decrease from 10 to 15 WPG. For a white-rot fungus Coriolus versicolor, it was counted until 12-15 WPG in the perishable hardwoods used, but not in a softwood Cryptomeria japonica, even at 6 WPG. In cases of another brown-rotter Serpula lacrymans and soil burial, effect of acetylation was intermediate between Tyromyces palustris and Coriolus versicolor. Anti-degradation mechanism by acetylation was discussed, from these weight loss - weight gain relationships, and the IR-and 13C-NMR spectral analyses of fungus-exposed wood.
M Takahashi, Y Imamura, M Tanahashi

Questionnaire - Fungal decay types
1985 - IRG/WP 1265
T Nilsson

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

Preliminary study of the fungicidal and structural variability in copper naphthenates and naphthenic acids
1996 - IRG/WP 96-30114
Copper naphthenates, an oil-borne wood preservative listed by the American Wood-Preservers' Association (AWPA), is manufactured by complexing copper(II) with naphthenic acids. Prior to AWPA listing as a wood preservative, field experiments showed that copper naphthenates generally had good stability and were active against wood-destroying organisms. Recently, however, there have been reports of some copper naphthenate-treated poles rapidly failing. One possible explanation for the varying effectiveness could be that the structure, and resulting biological activity, of the naphthenic acids used to make copper naphthenate may vary. To test this hypothesis several naphthenic acids and copper naphenates were obtained and their fungicidal activity against three wood-destroying fungi measured. In addition, the chemical structure of the naphthenic acids were examined by proton- and carbon- NMR. Different activities were observed, especially against a copper-tolerant fungus. Some apparent correlations were seen between the fungicidal activity and chemical structures for the few samples studied.
T Schultz, D D Nicholas, L L Ingram Jr, T H Fisher

The effect of certain wood extractives on the growth of marine micro-organisms
1977 - IRG/WP 438
S E J Furtado, E B G Jones, J D Bultman

Inhibition of wood-inhabiting fungi by actinomycetes
1981 - IRG/WP 1137
Actinomycetes of the genera Streptomyces, Micromonospora, Microtetraspora, Nocardia and Rhodococcus, isolated from wood, were laboratory tested for their inhibitory effects against the Basidiomycete fungi Polystictus sanguineus and Sistrotrema brinkmannii. One-third of the representatives of the genus Streptomyces which were tested produced significant inhibitory zones whereas actinomycetes belonging to the other genera did not.
M S Cavalcante, R A Eaton

Comité International Permanent pour la Recherche sur la Préservation des Matériaux en Milieu Marin. Information from the Wood Group
1980 - IRG/WP 460
E G B Jones

Nondestructive Evaluation of Oriented Strand Board Exposed to Decay Fungi
2002 - IRG/WP 02-20243
Stress wave nondestructive evaluation (NDE) technologies are being used in our laboratory to evaluate the performance properties of engineered wood. These techniques have proven useful in the inspection of timber structures to locate internal voids and decayed or deteriorated areas in large timbers. But no information exists concerning NDE and important properties of wood composites exposed to decay fungi. For our pilot study on several types of wood composites, we examined the relationship between nondestructive stress wave transmission, decay rate and the bending properties of OSB exposed to the brown-rot fungus, Gloeophyllum trabeum (MAD-617). The following measurements were taken: stress wave transmission time (pulse echo test method), static bending test (ASTM D3043-95), and decay (expressed as percent weight). Stress wave measurements correlated with strength loss and with increasing rate of fungal decay. Stress wave NDE has great potential as a method for inspection of wood composite load-bearing (in-service) structures, detection of decay in laboratory tests, assessment of chemical additives to improve wood composite durability, and prediction of long term composite performance.
B Illman, V W Yang, R J Ross, W J Nelson

Screening potential preservatives against stain and mould fungi on pine timber in Zimbabwe
1995 - IRG/WP 95-30063
The search for environmentally and toxicologically safer chemicals for use in the timber preservative industry against stain and mould fungi has been intensified during the past few years. Results of field tests with two chemicals previously evaluated in the laboratory are presented. The conventional sodium pentachlorophenate was the more efficacious chemical against stain and mould fungi, providing up 90% control at a concentration of 2.5%. A potential alternative, Stopstain a borate-based chemical, gave results only slightly better than the untreated control timber, at a concentration of 5%. Unless the environmental cost and toxicological hazards of traditional chemicals are highlighted the newer and safer chemicals will be reluctantly accepted by industry as they are regarded as being prohibitively expensive.
A J Masuka

Moisture content levels and decay of hemlock
1986 - IRG/WP 1287
As a model of decay conditions of wooden members in wooden houses, a decay test was set up in which samples of western hemlock (Tsuga heterophylla) under 4 moisture levels were examined. Each week the samples were weighed and if the weights indicated that their moisture contents were lower than the expected levels, distilled water was added. Every 8 weeks 3 samples from each condition were oven dried at 60°C for 48 hours, up to 48 weeks. After 48 weeks, 3 samples from each condition were oven dried every 16 weeks. The results obtained were as follows: After examining the samples for 96 weeks at 27°C, the mean weight loss of the hemlock samples kept at about 50-100% moisture content level was larger than those of the other levels. If the samples were dried every 8 weeks, the amount of decay in them was not significant. Decay was also not significant in the samples kept at approximately 20-30% moisture content level.
K Suzuki

The restricted distribution of Serpula lacrymans in Australian buildings
1989 - IRG/WP 1382
Temperature data has been gathered over a number of years, not only for flooring regions of various buildings in Melbourne, but also within roof spaces and external to the buildings. Findings are discussed in relation to the distribution of Serpula lacrymans within Australia, its restriction to certain types of building construction and its restriction to flooring regions. The subfloor spaces of badly-ventilated, masonry buildings are highlighted as being better suited than are the subfloor spaces of, for example, Japanese buildings for the activity of this fungus. Hence Serpula lacrymans is very restricted in its distribution in Australia, yet where it is active it does grow rapidly and causes rapid flooring failures.
J D Thornton

Monographic cards for wood-destroying fungi. [Fiches monographiques pour les champignons lignivores]
1970 - IRG/WP I 5B
C Jacquiot

On Donkioporia expansa (Desm.) Kotl. & Pouzar
1986 - IRG/WP 1285
Donkioporia expansa is found more often in houses than realised until now. Virulence tests according to EN 113 show not only an attack of oak, but also of other hardwoods and even soft-woods.
G Buchwald

Additions and corrections to recent names for some common decay fungi
1977 - IRG/WP 167
A Käärik

Effect of medium-term degradation of beech wood by erosive (Phanerochaete chrysosporium) and lignin-selective (Ceriporiopsis subvermispora) strains of white rot fungi on its selected physical properties
2004 - IRG/WP 04-40292
At the Faculty of Wood Sciences and Technology a fungal delignification of normal and tension beech wood by erosive and lignin-selective strains white-rot fungi has been studied. The pre-treatment of both kind of wood samples was accompanied by partial delignification and apparent changes of their physical properties influencing the polar liquids penetration.
R Solár, S Kurjatko, M Mamonová, J Hudec

Essais biologiques sur poteaux traités à la Wolmanit C.B. suivant le procédé Boucherie modifé
1974 - IRG/WP 336
D Lapetite, C Jacquiot, J Campredon

Blue stain in service on wood surface coatings. Part 3: The nutritional capability of Aureobasidium pullulans compared to other fungi commonly isolated from wood surface coatings
1993 - IRG/WP 93-10035
The nutritional capability of Aureobasidium pullulans was previously examined, using agar plate tests, with regard to nutrient sources that are potentially available in fresh and weathered wood (Sharpe and Dickinson, 1992). This study compared these findings with the nutritional capability of four other fungi (Alternaria sp., Cladosporium cladosporoides, Stemphylium sp. and Trichoderma sp.) commonly isolated from wood surfaee coatings. The liquid culture techniques were used to assess the relative abilities of the fungi to utilise a range of simple sugars, wood sugar alcohols, hemicelluloses, cellulose and lignin degradation compounds. The observations were used to explain why Aureobasidium pullulans is able to occupy so successfully, often in monoculture, the wood-paint interface niche.
P R Sharpe, D J Dickinson

Effects of acetylation on the dimensional stability and decay resistance of kenaf (Hibiscus cannabinus L.) fiberboard
1996 - IRG/WP 96-40059
The objective of this study was to investigate the influence of the acetylation treated kenaf fiber, Phenol formaldehyde resin content level, and three fungi species on the dimensional stability and decay resistance of high density non wood composition boards. A standard ASTM method was used to evaluate weight loss and thickness change. The linear shrinkage and expansion of each species were also determined. All specimens were exposed to decay chambers for 16 weeks. Test results indicated that most of the main factors significantly influence the thickness, length changes, and decay resistance of the high density kenaf fiberboards.
P Chow, T Harp, R Meimban, J A Youngquist, R M Rowell

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