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Results of chemical analyses in the field of wood preservation in the Bundesanstalt für Materialprüfung
1973 - IRG/WP 321
The results of qualitative and quantitative chemical analyses of wood preservatives are often the basis for evaluating the various works in the field of wood preservation. In the past 10 to 15 years a number of such works was carried out in the Bundesanstalt fur Materialprüfung, Berlin-Dahlem, dealing with the identification and effectiveness of wood preservatives and with methods of wood preservation. Fundamental realisations were made which will be summarised below. It seems advisable to differentiate between inorganic and organic chemical wood preservatives and methods of analyses. These are two distinct fields which differ also with regard to the analytical techniques applied.
H J Petrowitz
Collaborative field experiment: Analysis of copper and chromium in stakes of the four reference timbers
1982 - IRG/WP 3213
The stakes analysed belong to the Swedish set of the four reference timbers of the collaborative field experiment (Document No: IRG/WP/367). Before the field exposure 60 mm were cut off the end of each stake. This was done in order to be able to carry out chemical analyses as well as different types of testing. Some of the material has been used in softrot tests (Document No: IRG/WP/1151).
Chemical analysis of TnBTO in lap-joints
1999 - IRG/WP 99-20173
This research was performed as part of the EU project FACT (contract SMT4-CT96-2135) on field tests out of ground contact and ageing methods. The results reported here are part of the work on the experimental lap-joint standard (ENV 12037). TNO investigated the TBTO content of 32 lap-joints by analysing the tin content of 90 samples. The lap-joints were treated with two different TBTO-concentrations (0.5%; 1.0%) and different treatment methods (brushing, dipping, vac-vac treatment). Analysis took place after initial treatment and 6 months after field testing above ground at the test site at Delft, The Netherlands. The samples for analysis were taken from the top layer (first 3 mm) and from the inner part of the lap-joint. Preliminary tests with different extraction methods (AWPA, CTBA and DPI-FS) for tin analysis in wood showed the highest recovery rates for the AWPA method. Therefore extraction of the wood samples was carried out in accordance to the AWPA-A6-89-4 method. The extracts were analysed by ICP-AES. Results of the tin analysis are discussed referring to theoretical TBTO concentration, treatment method and sample origin.
A Voss, P Esser, W L D Suitela
Report of activity of CEN/TC 38: Test Methods for Wood Preservatives
1987 - IRG/WP 2287
Chemical Analysis of Southern Pine Pole Stubs Thirty-Nine Months Following Treatment with Three Methylisothiocyanate-Based Fumigants
2004 - IRG/WP 04-30349
Agricultural fumigants have been commercially used in the United States for over 20 years to control internal decay in utility poles and other wooden structures. Of the four fumigants which are currently used in the remedial treatment of utility poles, three are based on methylisothiocyanate (MITC) as being the principal fungitoxic component. Two of these MITC-based fumigants, liquid metham sodium and granular dazomet, chemically decompose within a utility pole to release methylisothiocyanate. The third MITC-based fumigant consists of 97% methylisothiocyanate in a solid melt form. Laboratory and field studies conducted as part of the Cooperative Pole Research Program at Oregon State University have demonstrated the efficacy of all three MITC-based fumigants. However, studies conducted to date have not evaluated the three fumigants under the same experimental conditions. As a result, a field study of the three commercial MITC-based fumigants was established in June, 2000 in southern pine utility pole sections. At the second inspection conducted 39 months following fumigant treatment, chemical assay borings were removed at various pole heights and depths and analyzed for concentrations of MITC using GCMS. The 39 month results showed that MITC concentrations were greatest at all pole heights and core depths in the pole stubs treated with the 97% MITC product. In addition, similar concentrations of MITC were found in the metham sodium and dazomet treated pole stubs. When compared to the corresponding chemical assay results at 13 months following fumigant treatment, the 39 month results showed a sharp increase in concentrations of MITC in the 97% MITC treated pole stubs and a sharp decrease in MITC concentrations in the metham sodium treated pole stubs. MITC concentrations remained relatively unchanged in the dazomet treated pole stubs from 13 to 39 months following fumigant treatment. When compared to a MITC threshold value for decay fungi proposed by Oregon State University, the chemical assay results at 39 months indicated all three fumigants are effectively protecting the zone of fumigant treatment (15.2 cm below to 15.2 cm above groundline) of southern pine pole stubs. However, the greatest protection within and above the zone of treatment was provided by the 97% MITC treatment. Future sampling and chemical analysis of the southern pine pole stubs are planned to monitor long term efficacy of the fumigant treatments.
R J Ziobro, J Fomenko, D J Herdman, J Guzzetta, T Pope
Applications of immunological methods to the analysis and detection of Lentinus lepideus Fr
1989 - IRG/WP 1422
Polyclonal antisera have been raised against the brown rot fungus Lentinus lepideus, a major cause of rot induced pole failure in the UK. Specificity studies have indicated that the antisera cross-react with a number of basidiomycetes but to much lesser extent with other fungi. The antigenicity of Lentinus lepideus and hence its molecular composition shows some alteration with culture age and change of substrate. Wood block decay experiments have indicated that dot-immunobinding assays based on the antisera can detect the presence of Lentinus lepideus in conditions of minimal weight loss, an initial field trial has indicated that cross-reacting antigens can be detected in artificially inoculated distribution pole stubs. These and other aspecta of the antigenicity and immunodetection of Lentinus lepideus are discussed in this paper.
H Glancy, A Bruce, D Button, J W Palfreyman, B King
Copper naphthenate-treated Southern Pine pole stubs in field exposure: - Part 1: Gradient & biodeterioration analysis 12 years after treatment
2000 - IRG/WP 00-30242
Naphthenates have been used for the preservation of timber and cellulose since their original identification in Russia in the early 1880's as part of a series of petroleum characterizations. Later work in the development of copper naphthenate as a heavy-duty preservative for poles led to the development of various treating cycles similar to other oil-borne systems. Recent work concerning the post treatment steam conditioning of copper naphthenate treated southern pine has determined that some amorphous copper naphthenate is converted to a crystalline cuprous oxide. In small laboratory tests, this was later determined to be less efficacious than copper naphthenate. This paper reviews the performance of actual pole-diameter stubs placed in a high hazard location containing both termites and potential for early decay attack. Various treating cycles were used to treat the pole stubs in this test including various post-treatment conditioning methods.
H M Barnes, M H Freeman
Non-destructive stress wave measurement of decay and termite attack in experimental wood units
1986 - IRG/WP 2256
The purpose of this study was to determine if stress wave analysis could be used to monitor the degradation of wood specimens exposed to the brown-rot decay fungi (Gloeophyllum trabeum) and of wood specimens subjected to attack by subterranean termites. One hundred fifty 3/4 by 3/4 by 12 in. Southern pine specimens were used for exposure to brown-rot decay fungi and two hundred twenty-five 3/4 by 3/4 by 12 in. Southern pine specimens were used for attack by subterranean termites. Lots containing twenty five specimens each were subjected to either brown-rot decay fungi or monocultures of subterranean termites for various lengths of time in order to produce a gradient series of wood degradation. The specimens were then stress waved and statically tested to failure in compression. Stress wave modulus of elasticity and stress wave time provided useful correlation coefficients when used to estimate the ultimate compression stress of the degraded wood specimens. For the brown-rot decay specimens, a correlation coefficient of 0.892 was achieved using stress wave modulus of elasticity, as calculated with original specific gravity and exposed stress wave time values, to predict ultimate compression stress. Stress wave time by itself provided a correlation coefficient of 0.729. For the termite attacked specimens, correlation coefficients ranged from r = 0.90 for the control specimens, to r = 0.79 for the attacked specimens. In this case however, stress wave time by itself was not affected by the degradation of the wood due to the fact that the termites devoured the early wood but not the late wood of each annual ring. Changes in stress wave modulus of elasticity and stress wave time values reflected changes in ultimate compression stress values during early periods of decay. From the results it appears that stress wave analysis can be used to accurately monitor the strength degradation of wood specimens exposed to brown-rot decay fungi. Similar results were found in the termite attacked specimens with stress wave modulus of elasticity but not with stress wave time alone.
R F Pellerin, R C De Groot, G R Esenther
Surface retentions of PCP, TCMTB and MTC obtained during a field trial of antisapstain formulations
1993 - IRG/WP 93-20002
Formulations containing NaPCP or TCMTB and MTC were included as reference products in a recent field trial of antisapstain formulations in Queensland. Retentions of these actives on the surface of treated sawn Pinus elliottii were monitored by ultrasonic solvent extraction of excised samples and analytical determination by high performance liquid chromatography. Distribution of actives with depth and longitudinal position were monitored for the particular dipping/draining schedule employed, and related to dip concentration and time since dipping. The analytical data provide a direct measure of surface retention in terms of active ingredients per unit area, the assessment method preferred by WG II Sub-group 3 at IRG 23. Even if only applied to these reference treatments, such analysis would facilitate comparison between trials conducted using widely varying treatment regimes and conditions.
D E Ferlazzo, M D Needham, M J Kennedy
The remaining concentration of inorganic wood preservative components in EN 252 stakes after ground contact
2000 - IRG/WP 00-50159
In order to determine the biological efficiency and the remaining concentration of different inorganic and organic active ingredients during service, EN 252 specimens were impregnated with 3 copper based wood preservatives. The stakes were installed in the test field of the DESOWAG GmbH, Rheinberg, for at least 7 years. At the end of the field test some of these stakes were divided into 10 uniform segments. Afterwards each segment was milled and mixed to guarantee a nearly homogenous sample. After further sample preparation like an acidic digestion the remaining concentration of the inorganic components copper, zinc, boron and fluoride were measured by means of AAS, ICP and an ion selective electrode. Concerning the remaining concentration the following ranking of the investigated active ingredients could be deduced: Cr (90%)> Zn (60%)> Cu (40-70%) >= F (40%) > B (concentration <10%). Furthermore the results show that the remaining content of copper differs depending on the wood preservative used. The lowest content was detected for the CCZnF-formulation, the highest for the copper-quat-preservative. Furthermore it is obvious that the rate of biological decay correspond well with the distribution of the wood preservative components in the segments.
E Melcher, H-W Wegen
Silafluofen: Novel chemistry and versatility for termite control
1995 - IRG/WP 95-30069
A novel silicon - containing insectizide, HOE 084498 ('Silafluofen'), with a favourable toxicological profile, has shown activity against a broad spectrum of agricultural and environmental health pests. Results from laboratory and field studies around the world have demonstrated that silafluofen is effective at protecting timber from attack by various species of termite and wood-boring beetle. As a termiticide, silafluofen, applied as a dust-toxicant, may suppress/eliminate Coptotermes sp. Ongoing field trials in France, in cooperation with CTBA, indicate that silafluofen, injected directly into masonry, has controlled Reticulitermes santonensis. No signs of termite activity have been observed in the treated part of an infested house since the application was made, 2 years ago.
A J Adams, A Jermannaud, M-M Serment
Chemical Analysis of Southern Pine Pole Stubs Thirteen Months Following Treatment with Three Methylisothiocyanate Based Commercial Fumigants
2002 - IRG/WP 02-30294
Agricultural fumigants have been commercially used in the United States for over 20 years to control internal decay in utility poles and other wooden structures. Of the four fumigants which are currently used in the remedial treatment of utility poles, three are based on methylisothiocyanate (MITC) as being the principal fungitoxic component. Two of these MITC based fumigants, liquid metham sodium and granular dazomet, chemically decompose within a utility pole to release methylisothiocyanate. The third MITC based fumigant consists of 97% methylisothiocyanate in a solid melt form. Laboratory and field studies conducted as part of the Cooperative Pole Research Program at Oregon State University have demonstrated the efficacy of all three MITC based fumigants. However, studies conducted to date have not evaluated the three fumigants under the same experimental conditions. As a result, a field study of the three commercial MITC based fumigants was established in June, 2000 in pentachlorophenol treated southern pine utility pole sections. At the first inspection conducted 13 months following fumigant treatment, chemical assay borings were removed at various pole heights and depths and analyzed for concentrations of MITC using GCMS. The 13 month results showed the concentrations of MITC were greatest at all pole heights and core depths in the pole stubs treated with the 97% MITC product. In addition, higher concentrations of MITC were found in the metham sodium versus dazomet treated pole stubs. The results of the initial sampling of the southern pine pole stubs are compared to results of the fumigant efficacy studies conducted at Oregon State University. In addition, the chemical assay results are compared to a proposed MITC threshold value based on the results of the Oregon State University fumigant studies. Future sampling and chemical analysis of the southern pine pole stubs are planned.
R J Ziobro, T C Anderson, D J Herdman, J Guzzetta, T Pope
Examination of power poles by computerized tomography
1980 - IRG/WP 2142
The technique known as computed axial tomography (CAT or CT) has become widely known because of the success it has achieved in medical imaging and diagnostics. It has now been used to give non-destructive crosssectional pictures of a variety of industrial objects, including wooden power poles, with a spatial resolution of about 1 mm (0.04 in.). It is obvious the benefits that would be derived from being able to locate and determine the location and extent of knots, surface checks, internal cracks or rot and penetration of preservative. The internal density and possibly straightness of grain may also be assessed.
J A Taylor, I L Morgan, H Ellinger
Leaching from field test stakes. Results from two different methods of analysis
1993 - IRG/WP 93-50013
Field test stakes treated with Boliden K33 containing copper, chromium and arsenic exposed at three different fields in Sweden and rejected due to decay, have in two studies been analysed regarding leaching and remaining preservatives. The stakes have been exposed during 20 to 43 years. The density of the stakes and content of copper, chromium and arsenic have been determined in the top part of the stakes (above ground) and bottom part (in ground) separately. The density of the stakes after exposure were similar in the top and in the bottom of the stakes while it was lower in the middle, ground line part. Leaching from small sections of the stakes indicate that 23% of copper, 19% of chromium and 25% of arsenic leached from the wood during exposure. Leaching from stakes to the environment, including the preservative in the totally lost decayed part, is, according to the analyses, 50% for copper, -4% for chromium and 36% for arsenic as an average for all stakes. The results from the two studies give different results. This focuses on the importance of sampling and methods of analyses as well as the necessity of being careful when evaluating the results.
F G Evans, M-L Edlund
Effects of chlorothalonil (CTN) and butylated hydroxytoluene (BHT) on microbial communities involved in the deterioration of wood using T-RFLP II: Results from field studies
2007 - IRG/WP 07-30429
The effects of Chlorothalonil (CTN) and Butylated Hydroxytoluene (BHT) on microbial species diversity in wood and the surrounding soil are being assessed by Terminal Restriction Fragment Length Polymorphism (T-RFLP). CTN was selected as a trial organic wood preservative, and the non-biocidal BHT was evaluated for its synergistic effects with CTN. ACQ-C was a positive control and untreated SYP stakes were negative controls. Tests were installed at two separate field sites in MS that represent two different AWPA hazard zones. Samples were taken every 3 months over a 15 month period and visually evaluated for termite attack and decay. Samples were processed and whole genomic DNA was extracted for molecular analyses. Upon initial amplification of DNA using both specific and general primers, the presence or absence of target fungi was confirmed using gel electrophoresis. We are currently using T-RFLP to analyze the patterns of microbial colonization over time and in response to external stimuli (i.e., wood preservative treatment) to identify potential shifts in microbial community. Preliminary results indicate that the presence of non-basidiomycete fungi (i.e. molds, stains, and soft rots) are uniformly distributed throughout the samples regardless of treatment, while basidiomycetes are less common and severe decreases in overall basidiomycete populations occurred during periods of drought at both test sites.
G T Kirker, M L Prewitt, S V Diehl
Microbial Community Analysis Using Terminal Restriction Fragment Length Polymorphism (T-RFLP) Analysis: Field Study Results
2008 - IRG/WP 08-20377
The effects of chlorothalonil (CTN) and butylated hydroxytoluene (BHT) on the fungal community in southern yellow pine (SYP) were assessed using terminal restriction fragment length polymorphism (T-RFLP) analysis. Field stakes treated with 0.25% and 0.37% ammoniacal copper quat (ACQ-C), 0.1 and 0.25% CTN, and 0.1 and 0.25% CTN combined with 2% BHT were installed with untreated controls in field sites in Mississippi. Stakes were sampled at 90 days intervals and rated for decay damage. Microbial DNA was extracted from wood and amplified using non-specific (bacteria and fungi) and specific (basidiomycete) primers. Alpha diversity (richness and diversity), species composition, and beta diversity, were all calculated using T-RFLP data. Results indicate the presence of wood preservatives containing biocides: (1) increases initial colonization by bacteria that decreases over time, (2) slows the initial colonization of field stakes by fungi resulting in lower richness and diversity that increased over time, and (3) increased richness and diversity of basidiomycetes. Preservative treatment also changed the community composition of bacteria, fungi, and basidiomycetes found in wood, that became more similar over time to untreated controls for fungi and basidiomycetes, but not bacteria. The beta diversity of treated samples was less similar in early stages of exposure (3-9 months), but coalesced over time into stable populations that were similar to fungal and basidiomycete communities in untreated controls, but still bacteria remained different. Correlations were found between depletion of 0.1% CTN and increasing bacterial and fungal diversity.
G T Kirker, S V Diehl, M L Prewitt, W J Diehl
Environmental Emission of Wood Preservatives: Interpretation of Data Relevant to BPD Risk Assessments
2009 - IRG/WP 09-50259
The risk assessments for the use of wood preservatives proposed by the OECD and used under the Biocidal Products Directive (BPD) (98/8/EC) require the derivation of leaching rates for active substances. These rates are to be used as input data in to agreed exposure scenarios. The leaching rates can be derived from laboratory testing and from field testing. The relationship between laboratory and field tests has been studied in order to determine the correlation between the two modes of testing. EN84 tests have been used as a method. However, the determination of environmental leaching rates is beyond the scope of this test and it has been found to over-estimate leaching. The OECD guideline 1 (dipping) test has been designed specifically to determine environmental leaching rates from UC3 wood. This paper compares the leaching fluxes derived from OECD guideline 1 dipping tests to those derived from field tests. This allows a comparison of both the magnitude of flux rates and leaching flux profiles derived from the two tests. The magnitudes of the flux rates require the application of correlation factors in order to get agreement; these factors are presented and found to be of the order 5 – 10. The leaching flux profiles are found to be very different when the flux rates are plotted against time. The laboratory test gives an “exponential” profile, i.e. a profile that decreases quite sharply with time and then levels off. The field test produces profiles that are “sawtooth” patterns with time. This “sawtooth” pattern correlates with rainfall. This is in agreement with, and confirms, data previously presented (Baines, 2008). In the present study, however, an alternative method of data analysis is explored. If the field data is normalised according to the amount of rain falling then it is found that the laboratory and field tests produce very similar leaching profiles. Thus, the contrast previously discussed is shown to be an artefact of the method of analysing the data obtained from field tests. This is due to the inherent variability of weather patterns with time that cannot be replicated in the laboratory. If annual average rainfall figures are used, the risk assessments at differing time points can be carried out as assessments at average rainfall amounts. This alternative method of data analysis according to rainfall rather than time suggests a method of analysing the models for OECD risk assessment that can increase their utility.
D G Cantrell
Stress wave and visual analysis of treated and non treated fence posts after 15 years in field test
2010 - IRG/WP 10-20449
Wood preservation may play an important role in protecting tropical rain forest. Basically, it can reduce pressure on natural resources by increasing wood durability. Field tests are conducted to simulate final use of woods under different environmental conditions. Visual analysis, non destructive testing, and non destructive evaluation techniques were applied to assess wood resistance and chemical preservative efficiency. In Brazil visual analysis is frequently applied in field tests while NDE (Non Destructive Evaluation) techniques have been very little used. We assessed the sound level of treated and non treated wooden fence posts after 15 years in field tests using stress wave and visual analysis techniques. We studied the following wood species: Eucalyptus saligna, Eucalyptus grandis, Pinus elliottii and Sclerolobium paniculatum. Additionally, two non-vacuum/pressure and one vacuum/pressure methods were used to impregnate the fence posts. Creosote, CCA, a mixture of creosote and used motor oil, and a formulation based on fluor chrome arsenate phenol were the chemicals applied. For each wood specie/chemical a combination of 10 samples was treated and other 10 samples for each wood species were used as control. The visual analysis and non destructive evaluation techniques were conducted according to the criteria proposed by the IUFRO. The stress wave timer Metriguard model 239A equipment was also used. These research results showed that the non-destructive analysis method using the stress wave timer device was an efficient alternative to rapidly measure sound level of the wooden fence posts in field test. The average velocity of wave propagation acquired by the stress wave timer was lower in decayed woods compared to sound ones. Also the average velocity of the wave propagation through the buried portion was lower than through the above ground portion of the wooden fence posts. The visual analysis and stress wave timer showed a good relationship as alternative approach to assess sound level of the fence posts in field test.
A Florian da Costa, R Faustino Teles, J Costa Gonçalves
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
Above Ground Field Evaluation and GC-MS Analysis of Naturally Durable Wood Species
2012 - IRG/WP 12-10764
Nine wood species are being evaluated in above ground field studies in Mississippi and Wisconsin. Candidate naturally durable wood (NDW) species are being rated at yearly intervals for resistance to decay, cupping, and checking. Field ratings after 12 months exposure are presented. To date, Paulownia tomentosa (PAW) and southern yellow pine (SYP) are least durable and cedars are the most durable in above ground exposure. Wood samples are being taken from the deck-boards and subjected to chemical analysis using GC-MS. Fatty acids from NDW species were extracted, derivatized, and analyzed along with commercial fatty acid methyl ester (FAME) standards. With few exceptions, results indicate that FAMEs are more abundant in NDW species. However, preliminary bioassays found no inhibition of select wood decay fungi by FAMEs at naturally occurring concentrations.
G T Kirker, A B Blodgett, S T Lebow, C A Clausen
A critical view on early indicators for above ground field performance of wood
2013 - IRG/WP 13-20509
Above ground field tests are quite often a balancing act between the provision of realistic test conditions, reliable statistics, and acceptable long test durations. Within this study we therefore reviewed 543 data sets from above ground field tests performed at 36 different test sites in 8 countries in Australia and Europe. The main objective was to investigate possible correlations between early stages of decay and the actual service life of the specimens. Therefore native soft- and hardwoods were considered as well as modified and preservative treated timber. It was shown that the average service life of test specimens can be predicted by using the median time till failure. By this the overall test duration can be significantly reduced. The use of ‘earlier’ predictors turned out to be problematic due to high variation of field test results, which are mainly related to the wide range of moisture regimes within above ground exposure. For in ground situations, rating 4, ‘failure’, is probably a relevant level for end of service, but in particular above ground exposures the decay acceptance level might be lower e.g. in decking. Therefore lower thresholds might be considerable and will allow for further time saving when testing wood above ground, but still providing realistic exposure conditions.
C Brischke, L Meyer, G Alfredsen, P-O Flæte, L Francis, M Hansson, P Larsson Brelid, J Jermer
Statistical analysis of durability tests - Part 2: Principles of time-to-failure and application on field test data
2013 - IRG/WP 13-20512
Service life prediction is an important topic in wood research, especially with regard to the Construction Products Regulation (CPR). Both laboratory tests as well as in-service performance testing is therefore essential, in combination with proper monitoring and analysis tools. A crucial concept is variability and the incorporation of variability in tests and analysis. In this paper we focus on the use of probability density functions (pdf) to describe time-to-failure in field tests as such build further on the pdf fitting as described in part I of this publication. The statistical approach elaborated here, shows that statistically sound results can be obtained even if data are censored, i.e. when for some samples the time-to-failure criterion has not been reached yet or when the exact date of failure is not known e.g. due to non-continuous monitoring, which is normally the case for field testing. Different wood species and treatments exposed in an EN 252 set-up are compared for the test site Hamburg, Germany, and illustrate how a reference product has a longer time-to-failure than e.g. pine sapwood, and shows the sharp failure of the latter. The comparison of double layer samples at different sites resulted in the calculation of acceleration factors compared to the Hamburg site. Also, acceleration factors for shaded and non-shaded set-up were calculated. Seemingly, such an analysis is valuable to rate different sites and to compare different set-ups. It is, however, important that objective and frequent monitoring is aimed at to improve the reliability of analysis and assessment of wood durability.
J Van den Bulcke, I De Windt, C Brischke, C R Welzbacher, A O Rapp, J Van Acker
Quantification of copper and chromium in field stakes after different exposure times: Remaining metal content and distribution
2013 - IRG/WP 13-50291
In order to determine the distribution of copper and chromium as well as their remaining concentration EN 252 specimens and thicker pine sapwood stakes (non standard format) were treated with a commercial CC salt in a vacuum pressure process. The stakes were installed in the test field of the Institute of Wood Research, Hamburg, in August 2010. In all cases three stakes were removed after 4, 8, 12, 16 and 20 months of exposure, whereby the metal content was analysed after sample preparation. Based on these data and under consideration of the analytical values of unexposed stakes the remaining metal content was calculated for the above and in ground section. The results illustrate that 84 % of the copper remained in the full EN 252 samples and 77 % in the non standard stakes whereas the chromium content corresponds to 95 % and 85 %, respectively. On the other hand the data illustrate that in both sample sizes the highest copper and chromium amount was found in the above ground portion after exposure.
T Liese, M Bahmani, E Melcher
Microbial Community Analysis of Naturally Durable Wood in an Above Ground Field Test
2014 - IRG/WP 14-10826
This paper presents preliminary results of an above ground field test wherein eight naturally durable wood species were exposed concurrently at two sites in North America. Surface samples were taken at regular intervals from non-durable controls and compared to their more durable counterparts. Terminal Restriction Fragment Length Polymorphism was performed to characterize the microbial (bacteria, fungi, and basidiomycetes) communities present. Differences were noted among wood species and seasonal shifts in microbial diversity were noted at both sites. Attempts to correlate diversity indices with decay ratings were unsuccessful, but differences in species richness were noted for several of the naturally durable species. Western red cedar had significantly fewer bacterial species compared to other wood species. Fungal and basidiomycete species richness differed due to site and fungal species richness increased with increased exposure. Clustering of fungal and basidiomycete communities suggests seasonal patterns of colonization at both sites, but was more defined in the more southern site; Saucier, MS (MS). Future analyses will focus on comparison of years to model successional patterns of bacteria, fungi, and basidiomycetes.
G T Kirker, S V Diehl, P K Lebow
Statistical analysis of 40 years of preservative in-ground stake testing in Australia
2014 - IRG/WP 14-20552
Wood is widely recognized as a valuable material, yet the natural durability of some wood species limits its use for certain outdoor purposes. For decades, a wide range of methods and chemicals have been developed to increase the resistance of wood against degrading microorganisms and termites. Preservative treatment has a long and widespread tradition in wood protection. Proper testing of the effectiveness of such preservatives is based on both lab and field trials. Cookson (2013) reported on Australia’s largest in-ground stake trial of wood preservatives. The preservatives tested include low and high temperature creosotes, PCP and various water-borne preservatives including CCA and copper chromate. The main timbers examined were sawn Pinus radiata sapwood, sawn Eucalyptus regnans heartwood, and E. regnans natural rounds (mainly sapwood). The number of treatments (preservative/retention/timber combinations) tested was 208, although not at every site. Samples were put on the field on eight sites across Australia and Papoea New Guinea. The significant amount of data necessitates a concerted approach, and therefore a statistical analysis of a selection of samples was performed: creosote (K55), PCP (5%) and CCA (Celcure A and Tanalith C) were selected using all loadings and all sites. Differences between sites, preservatives and loadings were clearly present and comprehensibly displayed in separate graphs. In addition, we attempted to calculate the Scheffer index for six different sites and linking it to failure of the samples to calculate the acceleration factors of the different sites, showing clear differences between the sites considering only low to moderate termite pressure. More work has to be done however to get a proper mapping of the SCI of Australia as well as to calculate the precise acceleration factors. In all, re-analysis of such datasets is invaluable.
J Van den Bulcke, L J Cookson, I De Windt, W Li, J Van Acker