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Interspecific variability of European oak durability against white rot fungi (Coriolus versicolor): Comparison between sessile oak and peduncle oak (Quercus petraea and Quercus robur)
2001 - IRG/WP 01-10393
The knowledge of wood natural durability against biologic predators enable its external use. The resistance of European oak wood was reported like durable according to the EN 350-2. However, some individuals may contain high durable wood. Our research was focused to understand this variability in oak population that represent the first french species (4.1 millions of ha). Natural durability of European oak heartwood (Quercus petraea and Quercus robur) against white rot fungi (Coriolus versicolor) was tested according to european standard EN 113. The experimental material consists in 23 oaks robur and 26 petraea oaks sampled from 9 French regions. For each tree, 3 twin samples were taken off from heartwood situated at 1.30 m from the bottom of the tree. Different effects were tested by hierarchic variance analysis: "species", "forest within species" and "tree within forest". The tree effect is very significant for biologic natural resistance. Variability between species was also demonstrated. Although the species effect is significant, it's relatively weak compared with tree differences (it was declared significant 5%). Durability classification was determined according European standard EN 350-1. 69.2% of petraea oak trees are classified as high durable, 19.2% durable, 7.7% moderately durable and 3.8% slightly durable. In the case of robur oak 91.3% of trees are classified as high durable and 8.7% durable.
N Ayadi, B Charrier, M Irmouli, J P Charpentier, C J Allemand, F Feuillat, R Keller

Possibility of use of wood species per class of biological risks. Attempt to determine criteria based on Pr EN 350-1/2/3
1992 - IRG/WP 92-2409
M Rayzal

Testing method for the treatability of wood
1994 - IRG/WP 94-40031
In order to test and classify the treatability of wood species in pressure treatment processes with water-based solutions, a laboratory method was developed which allows the testing of small samples and limited sections of a stem, e.g. sapwood. The penetration of different liquids was determined separately concerning the three anatomical directions of wood. The common parameters for pressure impregnation were used on sap- and heartwood of eight indigenous and tropical wood species. An elastic epoxy resin proved feasible for coating the samples on five sides. From the data of the testing method a measure for the treatability was calculated, allowing to classify wood species into four treatability classes analogous to prEN 350-2 (1993).
A O Rapp, R-D Peek

The natural durability of wood in different use classes
2003 - IRG/WP 03-10457
The natural durability of important European wood species has been tested on 3970 specimen in field trials. The wood was exposed at five test fields in Germany with different climates at each site in European hazard class 4 and 3 (with and without soil contact). Within EHC 3 it was distinguished between tree different expositions (end grain sheltered, unsheltered and with water trap). The test is now running for 3 years. The results have shown that the type of exposition (EHC 3 or EHC 4) has a strong influence on both: the decay activity and the durability determined as the quotient of decay of tested species and of decay of Scots pine sapwood. The test site had a strong effect on decay activity and time to failure, whereas the effect on durability was minor. Up to now it is not yet possible to calculate the final durability classification, but so far the field tests in soil confirmed the natural durability given in EN 350 (with the exceptions of Quercus robur and Robinia pseudoacacia, both were less durable than said in the standard). Whereas so far the above ground tests revealed a higher durability for all softwood species with coloured heartwood (heartwood of Larix, Pseudotsuga and Pinus) than classified in the standard EN 350. It is obvious that the current classification of natural durability is only valid for use in soil contact. Future amendments of the standard EN 350 seem to be reasonable. It is proposed to list durability class separately for in ground and for above ground use in the future.
U Augusta, A O Rapp

Is laboratory testing of decay resistance questionable as a single criterion for natural durability?
1996 - IRG/WP 96-20096
In a laboratory test set up over 20 hardwood species were evaluated according to the European Standard EN 350-1 including Basidiomycete and soft rot testing. Half of the species used were of a known natural durability. The Basidiomycete testing was carried out using Coriolus versicolor, Gloeophyllum trabeum and Coniophora puteana in a malt agar test similar to EN 113. From this test it was not possible to rank the wood species according to known natural durability, only a distinct differentiation between species belonging to the group of durability classes 1 to 3 and the ones of durability classes 4 and 5 was noted. Since most wood species with little information on durability are so-called lesser known species belonging to the tropical hardwoods, it seems that only limited additional information is gained from brown rot tests supplementary to white rot tests. Both types of laboratory soft rot tests according to ENV 807 (vermiculite and soil) are able only to identify significantly the durability classes 1 to 4 from class 5, although somewhat better indications are obtained from the soil test. It is evident that other types of fungal attack like blue-stain in service, being an important parameter for window joinery, is not correlated at all with natural durability data obtained from soil testing. It is concluded from this research that durability testing would be better hazard class oriented in order to identify functionality of the end products derived.
J Van Acker, M Stevens, T Van Cauwenberghe, T Seynaeve

A new concept for the evaluation of wood durability for out of ground contact using accelerated L-joint testing
1997 - IRG/WP 97-20123
Since the wood preservation sector is developing in favour of defining exactly the utilization of wood products and preservation techniques as a function of the envisaged hazard class, more in particular the hazard classes 3 and 4 (EN 350) there is obviously a need for a test method evaluating natural durability for out of ground contact applications. Based on the L-joint test as described in the European standard EN 330 a test method is under evaluation to determine the out of ground contact durability of various temperate and tropical wood species. Major parameters in the accelerated L-joint durability test are: the open joint structure, an exposure with 10° inclination facing sout west, tenon members in a 50/50 beech - Scots pine sapwood combination and a controlled drip irrigation system in the joint corner. This new concept is independent of specific coating systems and minimizes the variability in testing due to long dry periods under certain climatic conditions.
J Van Acker, M Stevens

Study of natural durability of Spanish Eucalyptus globulus wood
2007 - IRG/WP 07-10617
In some countries such as Australia, the wood of Eucalyptus globulus is recommended, due to its high durability, in risk situations where attack by organisms is likely to occur. In Galicia this species has been used for many decades for timber structures, which are still used. However, European Standard EN-350-2 places Eucalyptus globulus in the worst category of natural durability, a situation that does not correspond to the facts. The objective of this project is to determine the durability of this species against wood decay fungi and wood boring insects and to classify E. globulus in the abovementioned standard accordingly. To achieve this objective, laboratory and field tests against fungi and insect attack are being carried out. The preliminary results of the laboratory tests with white and soft rot indicate that the heartwood is durable (class 2), sapwood is not durable (class 5) and juvenile wood is not durable (class 5). The results obtained in the laboratory tests with the Lyctus indicate that the heartwood is durable (D), sapwood is sensitive (S) and juvenile wood is sensitive (S). The results obtained in the termite tests indicate that the heartwood, sapwood and juvenile wood are all sensitive (S). These results confirm the high durability of the heartwood of this species, pending the conclusion of the remaining tests.
D Lorenzo, M T Troya, M J Prieto, C Baso, M Touza

Natural durability and anatomical features of teak (Tectona grandis) from plantations in Costa Rica
2008 - IRG/WP 08-10671
Teak (Tectona grandis) possesses superior mechanical properties and durability and is thus frequently used as an alternative to impregnated timber in Europe. Demand on teak has resulted in severe exploitation of the tropical teak forests in recent decades, but today the imported timber originates mainly from plantations and is certificated according to the Forest Stewardship Council (FSC) policy. The origin of teak is Asia, which is still the most important producer of teak timber coming from both natural forests and plantations. Teak has been planted successfully in Central America. Since the 90’s, an Austrian forest company owns and maintains teak plantations in Costa Rica. In general, teak is very durable (class 1 according to standard EN 350-2) and the objective of the present study was to investigate whether the durability of plantation timber was in line with that determined in the standard EN 350-2. Since the trees are young (15-year-old), the trunks consist entirely of juvenile wood and the proportion of sapwood in the raw material is high. Natural durability of plantation teak wood from Costa Rica was tested according to standard EN 113 by means of brown- and white rot fungi (Gloeophyllum trabeum, Postia placenta, Lentinus lepideus and Trametes versicolor). Localisation of extractives in fresh sap- and heartwood as well as the propagation of fungal decay were studied by light microscopy and various staining techniques. The samples originated from butt- and top logs in longitudinal direction and inner and outer heartwood and sapwood in radial direction. In contrast to studies that have shown decreased mechanical characteristics of plantation teak to naturally grown timber, the durability of juvenile teak timber was in line with that determined by the standard. No significant difference in durability was found between butt and top log samples. The plantation teak sapwood was classified as moderately durable (class 3) while the outer heartwood was very durable (class 1). Only the heartwood portion near to the pith was classified as durable (class 2). The white rot fungus Trametes versicolor caused the most severe mass loss in the range of 16-19% for sapwood samples and 2-3% for the outer heartwood. The study concluded that the heartwood of plantation teak timber from Costa Rica fulfils expectations regarding the durability of the material. An on-going study will complete the mechanical behaviour of plantation timber.
U J Wolfsmayr, N Terziev, G Daniel

Study on the natural durability of Eucalyptus grandis wood from Argentina
2009 - IRG/WP 09-10689
In Argentina eucalypts are in second place of importance in planted area, after pines. Due to its high growth rates (from 35 to 55 m3/ha/yr), Eucalyptus grandis is the most important among the eucalypts planted in Argentina. Moreover, E. grandis is one of the species with the greatest potential in the country, because of its diversity of uses for high end and added value solid products. Due to the present interest of using eucalyptus wood for solid products, is of particular importance to know the wood characteristics of E. grandis from local plantations. Natural durability is a very important characteristic to determine wood applications. Nowadays, only some references are made about its durability, where it is usually classified as “low durability” wood but without greater precisions on the tests made. The objective of this project is to determine the durability of this species against wood destroying fungi and wood destroying insects and to classify E. grandis in the European Standard EN 350-2. To achieve this objective, laboratory and field tests against fungi and insect attacks are being carried out. The results of the laboratory tests with white, brown and soft rot indicate that the heartwood is slightly-moderately durable (durability class 4-3), juvenile wood is slightly durable-moderately durable (durability class 4-3) and sapwood is not-slightly durable (durability class 5-4). The results obtained in the laboratory tests with Lyctus brunneus and Anobium punctatum indicate that heartwood is durable (durability class D), juvenile wood is durable (durability class D) and sapwood is susceptible (durability class S). These results, together with the data obtained from the tests carried out up to now, indicate the slightly-moderately resistant of the heartwood of this species against wood destroying fungi, the resistant of heartwood and juvenile wood against dry wood destroying beetles and the low resistant of heartwood, juvenile wood and sapwood against termites.
D Lorenzo, M T Troya, J C Piter, M Sánchez, C Baso

Study on the natural durability of Eucalyptus globulus wood from Spain
2009 - IRG/WP 09-10690
The wood of Eucalyptus globulus is recommended in some countries, such as Australia, due to its high durability, in risk situations where attack by organisms is likely to occur. In Galicia this species has been used for many decades for timber structures and other uses, which are still used. However, European Standard EN 350-2 places Eucalyptus globulus in the worst category of natural durability, a situation that does not correspond to the facts. The objective of this project is to determine the durability of this species against wood destroying fungi and wood destroying insects and to classify Eucalyptus globulus in the above mentioned standard accordingly. To achieve this objective, laboratory and field tests against fungi and insects were being carried out. The results of the laboratory tests with white, brown and soft rot indicate that heartwood is durable (class 2), sapwood is not durable (class 5) and juvenile wood is not durable (class 5). The results obtained in the laboratory tests with the Lyctus indicate that heartwood is durable (D), sapwood is susceptible (S) and juvenile wood is susceptible (S), with the Anobium indicate that heartwood is durable (D), sapwood is susceptible (S) and juvenile wood is durable (D) and with the termite tests indicate that heartwood, sapwood and juvenile wood are all susceptible (S). These results confirm the high durability of the heartwood of this species against wood destroying fungi and dry wood destroying beetles and the low resistant against termites.
D Lorenzo, M T Troya, M Touza, C Baso

Fouling and Boring Organisms Deteriorating Various European and Tropical Woods at Turkish Seas
2010 - IRG/WP 10-10741
This study aims to investigate the diversity of fouling and boring organisms damaging wood material at Turkish coasts. Trials were carried out at six harbour sites throughout the seas surrounding Turkey. Wood samples were hanged down at a depth of six meters in the sea, for a period of one year. Identification of the organisms obtained from wood plates revealed the presence of five wood borer and 26 fouling species. Iskenderun harbour had the highest boring organism diversity (five species), followed by Trabzon, Finike harbours (three species) and Bandirma, Eregli and Alaçati harbours (two species). The two molluscan boring species, Teredo navalis and Lyrodus pedicellatus were present at all harbour sites, but Nototeredo norvegica occurred only at Trabzon and Iskenderun harbours, Bankia carinata only at Iskenderun harbour, and the crustacean wood borer Limnoria tripunctata at Finike and Iskenderun harbours. All native tree species, except for the olive, were significantly impacted from fouling and boring organisms.
S Şen, H Sivrikaya, M Yalcin, A Kerem Bakır, B Öztürk

Improved analysis of field test data related to service life prediction of tropical wood species
2010 - IRG/WP 10-20458
Long field trials of wood in ground contact give valuable data on the natural durability of the material. The European Standard EN 350 gives guidance on how to perform these durability classification, but is limited to the use of averages of in-service life of a set of specimens compared to a reference set. Starting from a database of visual assessment of field stake testing, it is possible to obtain a durability classification based on Weibull distributions and accompanying percentiles. For this study a set of 39 Malaysian timber species, exposed for over 30 years, is used. The in-ground durability of the stakes was tested and decay was rated according to ASTM D1758. Weibull statistics and the approach as applied in EN 350 standardization are compared. By taking into account the use of reference specimens, these classifications could be transferable to other climatic regions in order to harmonise durability and with the ultimate goal to get general applicable statistical data on durability, going beyond classification, and related strength with regard to the biological nature of wood.
J Van den Bulcke, A Wong, Ling Wang Choon, Yoon Soo Kim, J Van Acker

Focus on the European standardization - Towards a revision of the EN 350 natural durability standard: a different approach to the inherent resistance and performance of wood and wood-based materials
2013 - IRG 13-10811
The European standard EN 350 “Natural durability of solid wood”, Parts 1 and 2, is one of the fundamental standards developed by the CEN/TC 38 “Durability of wood and wood-based products”. This standard is widely used by wood industries as the reference document which provides information on the resistance of wood species used in mainly the construction sector against decay fungi, wood-boring beetles and termites as well as information on wood species’ capacity to be impregnated with wood preservatives. The standard also refers to the appropriate standards for testing these properties of wood and provides criteria of interpretation of such tests’ results. The changes that have occurred over the last few decades on the European market, including the appearance of new wood-based products such as modified wood, the publication and application of new regulations (Biocidal Directive/Regulation, Construction Products Directive/Regulation) and the evolutions of customers’ expectations in terms of the service life of the wood-based products which they may use, make it crucial to initiate a deep revision of the EN 350 standard. The new version would take into account the revisions made recently in related existing standards, the modifications that have occurred on the European market of wood products, and the outcomes of recent national and European research projects in order to provide a robust and relevant decision tool to all those who rely on wood.
M Kutnik

Towards durability classification of preservative treated wood – first attempts using different European standards
2018 - RG/WP 18-20638
EN 350 (2016) gives guidance on methods for determining and classifying the durability of wood and wood-based material against biological wood destroying agents. “Wood-based materials are those derived from trees and include amongst others: untreated wood, heat treated wood, chemically modified wood, glue laminated wood, wood-based panels, wood polymer composites and wood treated with wood preservatives”. Very few data are yet available for assigning durability classes to preservative treated wood on the basis of results from test methods referred to in EN 350 (2016). In this study results from tests according to EN 113 (1996), ENV 807 (2001), and EN 252 (2014) were evaluated, for assigning durability classes of differently preservative treated wood, using different classification schemes. Specimens made from beech (Fagus sylvatica) and Scots pine (Pinus sylvetris) were treated with four different retentions of two wood preservative systems. Results show, that different tests lead to durability classification between 1 (very durable) to 5 (not durable) for same tested combinations. Most treated wood achieved higher durability classes based on test against basidiomycetes (EN 113) compared to tests against soil inhabiting micro-organisms (ENV 807 and EN 252). In summary, it became evident that durability classification of preservative treated wood strongly depends on both, the applied test method and the evaluation scheme used for assigning durability classes.
S Bollmus, A Gellerich, C Brischke, H Militz

Development of procedures for sampling, testing, and classification to determine the biological durability of wood and wood products
2020 - IRG/WP 20-20676
This paper informs about a research project, which deals with several shortcomings and a lack of clarity within EN 350:2016. The project started in January 2020, will run for 3 years, and is operated by the Institute of Wood Technology Dresden (IHD) and the University of Goettingen (UGOE). Determination and classification of durability of wood and wood products against wood-destroying organisms is regulated by EN 350. By the revised version of 2016, its scope has been extended to processed wood, including heat-treated, preservative-treated and otherwise modified wood as well as wood-based materials. Neither the standard itself nor the indicated test methods allow a durability classification in a comprehensive manner. Aim of the project is to develop applicable methods for sampling and durability testing as well as an adequate classification system, enabling a comparative performance evaluation of different products. After identifying the product-specific, methodological development needs, selected products and materials from various groups will be investigated, using both laboratory and field test methods. Based on the results, a technical guideline will be compiled, which will include aspects of sampling, testing, durability classification, and recommendations for standardisation and product declaration.
W Scheiding, K Jacobs, S Bollmus, C Brischke

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

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

Studies on accelerated ageing procedures with TBTO-treated wood
1985 - IRG/WP 2244
The efficacy of various procedures for accelerated ageing of organotin based wood preservatives in treated wood has been investigated. It was found that leaching of the treated wood samples in water according to the European Standard EN 84 was not satisfactory for organotin based preservatives and is probably also unsuitable even for other types of organic solvent preservatives. Keeping tributyltin oxide (TBTO) treated samples in a heating cabinet at 70°C for five weeks, however, had a considerable effect on the breakdown of TBTO and the subsequent decay test. Therefore, an ageing procedure involving a heating period should be considered for all organic solvent wood preservatives. The investigation also confirmed that elevated temperatures accelerate the degradation of TBTO and that there is a strong correlation between the percentage of TBTO in the wood and its resistance against decay.
J Jermer, M-L Edlund, B Henningsson, W Hintze

Temperature influence on the growing velocity and cellulolytic activities of Poria placenta strains from several locations
1986 - IRG/WP 2263
The differences observed on the FPRL 280 Poria Placenta strain at several Research European Laboratories for determining up the fungicide effectiveness of wood preservative has carry us to do a comparative study about the cellulolytic activity and growth velocity of each of this strains at different temperatures (22, 24 and 28°C). The results show significative differences when the temperature is changed.
A M Navarrete, M T De Troya

Rapport sur l'activité du CEN/TC 38
1983 - IRG/WP 2204
M Pottevin

Depletion of boron and copper from CCB treated test specimens using different leaching protocols
2004 - IRG/WP 04-50208
The objective of this study was to measure the depletion of inorganic wood preservative components regarding the proposed OECD guideline "Estimation of emissions from preservative-treated wood to the environment: laboratory method for wooden commodities exposed in the use class 4 and 5" as part of the project "Investigations concerning the influence of test parameters on the release of biocidal actives from treated timber in leaching tests". Pine sapwood specimens (50x10x150) were pressure impregnated with CCB according to European Use Class 4. Before leaching all samples were stores 4 weeks for fixation. In addition leaching tests were performed according to the European Standard EN 84 by means of EN 113 blocks. Parallel investigations were carried out between two laboratories to assess the repeatability and comparability of the methods. The results of chemical analysis of leachates taken at different time intervals show that similar depletion rates were determined for copper and boron independent on the leaching protocol used. However, the loss of copper as well as chromium in short term dipping experiments was often lower than the detection limit. Furthermore it can be stated that the difference between parallels was higher for the results which were obtained for the OECD guideline that EN 84. A comparison of both laboratory results indicate that a quite good repeatability is given in case of the CCB treated material.
E Melcher, R-D Peek, U Schoknecht, R Wegner

Resistance of the wood of Eucalyptus saligna and Paulownia tomentosa against some wood rotting fungi
1997 - IRG/WP 97-10238
Paulownia tomentosa and Eucalyptus saligna are not autochthonous species in Slovenia and we determined the resistance of their wood against our most common wood rotting fungi. The resistance against Coniophora puteana, Gloeophyllum trabeum and Trametes versicolor was determined according to EN 113 and compared to the resistance of beech (Fagus sylvatica) wood. It was stated, that both paulownia and eucalypt wood samples are much more resistant than beech wood. Especially paulownia wood was outstanding by its natural resistance against tested basidiomycetes.
F Pohleven, M Petric

Determination of the preventive efficacy against wood destroying basidiomycetes fungi, EN V 839 - CEN/TC 38 WG 9
1993 - IRG/WP 93-20015
The WG 9 of CEN TC/38 has presented to EC a mycological test to assess efficacy of preservatives applied by surface process. This method is now an experimental standard (EN V 839) which has to be approved by the different european delegations. The following paper is not the standard as it has been proposed but is a presentation of the principle of the method. The experimental standard specifies a laboratory method of test which gives a basis of the assessment of the preventive action of a wood preservative when applied as a surface treatment against Basidiomycetes fungi. This method is applicable to formulations of preservatives in a ready to use form (organic formulations, organic water-dispersible formulations, water-soluble materials). Series of susceptible wood species specimens are treated on longitudinal faces whith the preservative in test using brushing as surface procedure. Test specimens are then exposed by an intermediate mesh to feeder blocks infestedby pure culture of Basidiomycetes fungi in sterile conditions and penetration of fungi is assessed on cross section sawn in the samples at the end of the test.
D Dirol

Tebuconazole, a new wood-preserving fungicide
1990 - IRG/WP 3634
TEBUCONAZOLE, an anti-fungal triazole compound, has been tested to assess the effectivness as wood preserving fungicide. Tests were made with the active ingredient and also in formulations against basidiomycetes, blue-staining fungi and mould. Results of the DESOWAG laboratories and also from official institutes will be presented. In addition to this there were made different toxicological and ecotoxicological trials according to OECD and EPA guidelines
B Wüstenhöfer, H-W Wegen, W Metzner

CEN Draft Standard (38 N 460F): Méthode d'essai pour determiner l'efficacité d'un produit de préservation du bois en milieu marin
1986 - IRG/WP 4132 F
G Castan

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