Your search resulted in 24 documents.
Respiration measurement of dry-rot
1995 - IRG/WP 95-10095
Methods for measuring the production of carbondioxide from wood infected with the dry-rot fungus were evaluated. By enclosing whole wood blocks and measuring the concentration of gas in the headspace by gas chromatography, an exponential increase in the concentration of CO2 was observed for at least 2 months. This technique could therefore present a method for evaluating various treatments of dry-rot in the laboratory. Collecting headspace gas from GC-vials inserted in drilled holes in infected wood showed an increase in CO2 concentration for 2 weeks, whereafter it decreased. This method will be evaluated for use in naturally infected timber in buildings to measure the activity of attacks where the viability of the fungus is in doubt. A specific growth rate of 0.037 days-1 for dry-rot in infected wood was calculated. It was also shown that the growth of dry-rot was inhibited by either CO2 partial pressures higher than 100 mbar or O2 partial pressures lower than 100 mbar.
Direct measurement of fluid flow within wood
1986 - IRG/WP 2248
The problematics of fluid flow mechanism within wood using a permeability concept are highlighted, and the non-feasibility of a practical and versatile model is explained. An alternative method using a negative temperature coefficient thermistor to measure flow velocity directly is presented. The method has been verified in living trees and shows extreme sensitivity for flow above 1 meter/hour. For measuring lower velocities, the method needs improvement.
J P Hösli
Rates of emission from CCA-treated wood in the marine environment: measurement, modelling and requirements for further research
2001 - IRG/WP 01-50166-12
Accurate estimates of rates of emission of leachate from preservative treated wood are crucial for realistic predictions of the environmental impact of its use in maritime construction. Estimates are available for some commonly used preservatives, but these vary widely. Though variable, these measurements suggest that emission generally decreases exponentially with time. Part of the variation is due to differences in methodology employed. Physical and chemical characteristics of the seawater used (e.g. temperature, salinity, pH and oxygen content) affect emission rate. So too do the specifics of the treatment process especially the preservative formulation used, and pre- and post-treatment handling of the wood. The nature of the treated wood samples is also important, with misleadingly high estimates being obtained from samples with unrepresentatively high proportions of cross-cut surfaces. A suggested strategy for developing an informative and standardised methodology is discussed. To form useful models of impacts of leaching, emission rates need to be considered in conjunction with site-specific information regarding a) water exchange rates between the area where leaching occurs and the sea, and b) the extent of partitioning of leachate between the water column, biota and sediment. The risk of environmental impact may be reduced by modification to treatment procedures and by careful planning of installation.
S M Cragg, C J Brown, R A Albuquerque, R A Eaton
The Rubber Ruler: Continuous measurement of dimension changes in wood panels
1994 - IRG/WP 94-20033
A new application for a linear transducer called Rubber Ruler was developed. Rubber Ruler provides a simple and reliable method for continuous monitoring of dimension changes in wood panels. This paper presents the methodology. Results of priliminary experiments designed to simulate the movement in wood panels are also discussed.
Siew K Ho, P Vinden, P Kho
Use of Transverse Compression Properties as a Measurement of Wood Biodeterioration, Part 1 of 2 - Effect of White-Rot on Yellow-Poplar
2002 - IRG/WP 02-40239
The soil block and agar block test methods are used extensively as a screening process for potential and modified wood preservatives. The extent of decay in standard screening tests, indicative of preservative efficacy, is currently based on mass loss. Mass loss techniques, due to their limit of sensitivity in detecting significant mass loss vis-à-vis decay, require an extended fungus exposure period of the test specimens. Alternatively, an analysis of the effects of decay using mechanical loss test methods offer the possibility to significantly decrease the amount of time required to perform screening tests. Since a reduction in mechanical properties is continuous from the onset of decay, the exposure period of test specimens used in mechanical loss analysis is limited only by the sensitivity of the test apparatus to measure significant mechanical property loss. In the present study, the use of transverse compression, both radial and tangential, was evaluated as a method to quickly, and accurately, measure the extent of decay in thin yellow-poplar wafers exposed to a white-rot fungus in a soil block test. Within transverse compression, two properties of mechanical loss, compression strength at 5 % strain and modulus of elasticity to proportional limit were compared. While both methods of mechanical loss analysis proved to be a much quicker in determining significant decay than did mass loss, elastic loss appeared to offer a more accurate means of distinguishing the outset of significant decay than did strength loss.
S Janzen, D D Nicholas
Measurement of VOC emissions from curative treated wood: A new emission test chamber
2001 - IRG/WP 01-50166-13
A poor indoor air quality (IAQ) is now recognized as a potential factor affecting occupants health. There are three basic strategies to improve IAQ: source control, improvement of the ventilation and use of air cleaners. Usually, the most efficient way to improve IAQ is to eliminate the different pollutant sources or to reduce their emissions. In order to precisely measure emissions from building products and estimate the potential heath impact of emitted pollutants, standardised analytical methods are needed. The aim of this paper is to present the new standards prepared by the European Committee for Standardization (CEN) and the International Organization for Standardization (ISO) for the measurement of indoor air pollutants and their application to the characterization of emissions from wood products. The prestandard ENV 13419, subdivided in three parts, has been prepared by the CEN technical committee 264 : ??ENV 13419-1 : Building products - Determination of the emission of volatile organic compounds - Part 1 : Emission test chamber method, ??ENV 13419-2 : Building products - Determination of the emission of volatile organic compounds - Part 2 : Emission test cell method, ??ENV 13419-3 : Building products - Determination of the emission of volatile organic compounds - Part 3 : Procedure for sampling, storage of samples and preparation of test specimens. The two first parts of the prestandard ENV 13419 specify a general laboratory test method for the determination of the area specific emission rate of volatile organic compounds (VOCs) from newly produced building products under defined climate conditions in a test chamber (Part 1) or cell (Part 2). The third part specifies for solid, liquid or combined products, the sampling procedure, transport and storage conditions and preparation of test specimens. In France, those European prestandards have been translated by the French Normalisation Association (AFNOR) in three experimental standards : XP ENV 13419-1, XP ENV 13419-2 and XP ENV 13419-3 [1-3]. In parallel to the ongoing work at CEN, the technical committee 146 of International Organization for Standardization (ISO) has prepared the draft international standard ISO/DIS 16000 related to indoor air. Part 6 of this standard specifies a method for the determination of the emission of single volatile organic compounds (VOCs) and total volatile organic compounds (TVOC) from building materials using test chambers and cells : ??ISO/DIS 16000-6 : Indoor air - Part 6 : Determination of volatile organic compounds in indoor and chamber air by active sampling on TENAX TA sorbent, thermal desorption and gas chromatography using MS/FID. It is intended that, after the final voting stage, the CEN prestandards (Parts 1-3) will be taken over by ISO and that Part 6 of the ISO standard will be taken over by CEN as the fourth part of the ENV 13419 prestandard. As an example, the volatile organic compounds emissions from preservative treated wood samples were characterised according to the CEN ENV 13419-1 prestandard describing the emission test chamber method and to the ISO/DIS 16000-6 prestandard for the analytical method. Two representative wood preservatives (hydrodispersable and petroleum solvent formulation) were tested for this purpose. The VOCs concentrations in the test chamber were monitored during 6 days following a simulated curative wood treatment.
F Maupetit, O Ramalho, C Yrieix
The effect of low molecular weight chelators on iron chelation and free radical generation as studied by ESR measurement
2000 - IRG/WP 00-10367
The focus of this work was to improve our current knowledge of the non-enzymatic mechanisms involved in brown-rot decay. Electron Spin Resonance (ESR), also known as Electron Paramagnetic Resonance (EPR), is an attractive technique for the identification and study of chemical species containing unpaired electrons (such as radicals and certain transition metal species). ESR spin-trapping techniques are also commonly used to study very reactive and short-lived free radical species. It has been proposed that low MW chelators as well as Fenton reagents are involved in wood brown-rot decay, at least in early non-enzymatic stages. In this work, the binding between a chelator model compound and ferric iron was studied by ESR spectroscopy. The effects of the chelator model compound, Fenton reagents, as well as the reaction conditions on free radical generation were also studied using ESR spin-trapping techniques. The results indicate: 1. The relative amount of ferric iron bound to chelators is directly related to the chelator / iron ratio in the system. The relative quantity of the chelator-iron complex can be determined by measuring the intensities of the characteristic g4.3 ESR signal. 2. The effects of the chelator/iron ratio, the pH, and other reaction parameters on the hydroxyl radical generation in a Fenton type system could be determined using ESR spin-trapping techniques. 3. Data support the hypothesis that superoxide radicals are involved in the chelator mediated Fenton processes.
Yuhui Qian, B Goodell
Alternative technologies for wood wastes recycling - Part B: Biotreatment of PCP- and creosote-treated wood
1998 - IRG/WP 98-50101-18 b
Alternative technologies have been investigated to detoxify treated wood. Two classes of organic compounds are studied. Creosote-treated wood are classified in France as dangerous wood wastes. A conventional incineration could be provided for these wood wastes but the cost of this elimination could be very high (> 2000 FFR/ton). For these reasons, we have tested two kinds of new processes as alternative ways. The developed strategy is described in this paper and illustrated by a few examples. Part B - The second one is based on an oxidative degradation of organic compounds directly in the wood: oxidative degradation by fungi. Few examples are presented in this paper. Three fungi are tested directly on treated wood. High levels of contaminants are tested around 0.6 g of PCP/kg and 3.7 g of 8 PAH/kg of wood. Few oxidation products generated by this biological treatment are identified. An ecotoxicological assessment is performed to validate this process. Technical feasibility of these developed processes as well as economic aspects are discussed,
S Legay, P Marchal, G Labat
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
Computerized axial tomography. A non-destructive method for three-dimensional wood density/moisture content measurement
1987 - IRG/WP 2285
Computerized Axial Tomography (CAT-scanning) - used for medical investigations of the brain - has been evaluated as a nondestructive method of three-dimensional wood density/moisture content measurements. Density can be measured with an accuracy of ±3 kg/m³, and the accuracy in average moisture content is ±1% below and above fibre saturation point. It is theoretically possible that measurements can be made in a randomly chosen volume element of 2 x 2 x 10 mm³ within a wooden testpiece. CAT-scanning has also possibilities for evaluating: - the development of fungal attack on wood; - the development of attack by marine borers on wood; - the distribution end penetration rate of preservatives in wood; - wood drying after impregnation.
L O Lindgren
Service Life Prediction of Wood Claddings by in-situ Measurement of Wood Moisture Content
2004 - IRG/WP 04-20304
The Danish Technological Institute is in co-operation with industry partners running a project aiming at predicting the service life of different wood protecting systems. The project focuses on examining the moisture reducing effect of different wood claddings and the ability to maintain the appearance of the surfaces, when the wood is used in service class 3. A façade construction is exposed to weathering at the field test area of the Danish Technological Institute (near Copenhagen). In specific locations of the construction in-situ measurements are measured of the wood moisture by using resistance moisture meters. Once a year the surface is evaluated in relation to appearance, mould growth and degradation. The examination comprises different types of coating treatments (e.g. non-permeable and permeable and solvent and water-based types). In addition, a system based on stabilising oil treatment similar to the Royal process is examined. This paper presents results after only one-year of exposure. It is intended to extend the testing period for at least 5 years. Furthermore, it is our intention to include a number of other systems and in the future to be able to perform benchmarking between different systems. It is at the same time the intention that testing should form the basis of evaluation of the maintenance requirement and the service life of the wood.
B Lindegaard, N Morsing
The potential application of rapid gas-chromatographic assay of microbial respiration to the monitoring of wood decay in field trial situations
1983 - IRG/WP 2196
Gas chromatographic detection of microbial activity (C02 production) within stakes in a field trial situation would appear to provide a sensitive, non-destructive and relatively rapid method for the quantitative assessment of preservative treatments. Most consistent results were obtained when stakes were removed from the soil, washed, saturated with water and incubated in sealed PVC tubes at 25°C for 24 h prior to assay of gas samples from the tubes. Each assay took 1.6 min to perform and stakes were returned to the field within 48 h. Microbial activity was readily detected in untreated Eucalyptus regnans stakes after 18 days field exposure. Stakes pressure impregnated with CCA, busan-30 or creosote displayed consistently low levels of activity to the present time (3 months after insertion).
M A Line
Development of software to automate the quantification of checking occurring in preservative treated wood exposed to weathering
2001 - IRG/WP 01-20228
Surface checking often disfigures the appearance of wood treated with water-borne preservatives and treatments designed to reduce such checking have been receiving increasing attention. Progress in this area has however been slowed by the lack of a method of rapidly and accurately quantifying checking at treated wood surfaces. A software package has therefore been developed which identifies, measures and records the dimensions and numbers of surface checks in scanned images of preservative treated wood specimens. The program uses grey-scale 600 dpi TIFF images of wood specimens and operates within the data acquisition, analysis and presentation software IgorPro (Wavemetrics). Procedures within the program analyse images sequentially pixel by pixel and one row at a time searching for brightness minima (dark areas) which satisfy criteria that are characteristic of checks. A black and white (b/w) image is then produced in which probable checks are shown black on a white background. Further procedures reduce noise in the b/w image eliminating artifacts (specks of dirt) and small checks that cannot be discerned by the naked eye. The final stage of the analysis rasters through the cleaned b/w image establishing which black pixels connect to each other and identifying and labeling checks and quantifying check positions, sizes and shape. These data are then presented in a spreadsheet. Using this package it has been possible to successfully quantify checking in a range of preservative treated wood specimens that have been subjected to natural weathering. This paper describes the principal features of the software package and presents preliminary data from analysis of treated and weathered specimens. The advantages of the system for quantifying checking in preservative treated wood as well as its limitations are discussed.
A G Christy, P D Evans
Measurement of electrokinetic potential to evaluate adsorption of quaternary ammonium salt
1991 - IRG/WP 3672
Measurement of z-potential in the wood treated with preservatives is suggested as a method for determination of the adsorption of preservative to wood. It has been found that measurement of z-potential of wood treated with quaternary ammonium salt type preservatives can be a useful method to determine the adsorptives phenomena of preservatives and by which there is a remarkable differences in the adsorbed condition with the components of preservatives concentration of treating solution, treating time and the elapsed time for streaming potential measurement in wood treated with quaternary ammonium salt type, there were differences in values of z-potential against that of untreated wood with a difference in chemical formula of preservatives, addition of chemicals for polymerization and concentration of treating solution. In case of the wood treated with quaternary ammonium salt with silicon, the treating time to reach the completly adsorbed condition of preservatives was about 3-5 minutes in concentration of below 0.75% and was about 15 minutes in above 1.5%. On the other hand, in adsorption of benzalkonium chloride, it took 15 minutes of adsorbing time in below 0.75% and 7.5 minutes in above 1.5%. Regardless of the extension of elapsed time for measuring, the constant values in z-potential was not obtained in wood treated with quaternary ammoniusalt with silicon, this result was attributable to leaching of preservatives. Whereas, for measurement of wood treated with benzalkonium chloride, it took the measuring time of 15-20 minutes to obtain constant values which mean a stable condition in adsorption.
Yeong Suk Kim
Measuring Soil Respiration as a New Approach to Describe the Interaction Between Wood (Treated and Untreated) and Microbiologically Active Soil
2006 - IRG/WP 06-20344
Soil respirometry was employed to examine the relationship between both the performance of copper organic preservatives in contact with and the amount of carbon dioxide evolved from soil and the effect of wood treated with preservatives on carbon turnover in soil. Wood was treated with a range of copper organic preservatives intended for use in ground contact as well as an organic preservative intended for use above ground. The treated wood was incubated in columns of microbiologically active soil for 9 months. During the initial 6 months, carbon dioxide being evolved from the soil was measured on a continuous basis using an infrared gas analyser. Soil metabolism was stimulated at a number of ‘trigger’ points during the initial 6 months of the study and the impact of the presence of the treated wood on both basal soil respiration and substrate induced respiration was measured. After 9 months, the wood samples were removed from the soil column and any mass loss was recorded. The relationship between carbon dioxide evolved from the soil and mass loss was investigated. This paper presents initial data from this study. It describes the system employed and the outcome of a number of key events. Mass loss is described and initial correlation data is presented. The method appears to present a useful approach to investigating the impact of wood treatments of localised carbon turnover in soil and may provide a predictive model for assessing the performance of treatments intended for use in wood in contact with soil.
I Stephan, W Mierke
Wood protection, a tool for climate change mitigation?
2008 - IRG/WP 08-50257
In the context of global warming and the search for possible strategies to mitigate climate change, forest and forest products have important advantages. Sustainable management makes forest a carbon sink, wood products have the potential to be a carbon sink as well, and their low carbon intensity is a potential for reducing CO2 emissions by substitution to competing materials. After describing these assets of wood products, this paper analyses how wood protection can reinforce them. This reinforcement effect is probably important, but still needs to be quantified.
Measurement of wood decay by dynamic MOE in an accelerated soil contact test
2008 - IRG/WP 08-20390
Current laboratory and field testing of preservatives involves various techniques to determine the extent of fungal attack, including visual inspection, mass loss, and static bending and compression strength measurements. The objective of this study was to compare decay measurement by conventional compression strength versus dynamic MOE, employing small wood stakes in an accelerated laboratory soil-contact wood decay test. The maximum decay was generally observed close to the center of the stake. An average correlation of 0.884 was observed between the average compression and dynamic MOE strength losses.
Gan Li, D D Nicholas, T P Schultz
Service Life Prediction of Wood Claddings by in-situ Measurement of Wood Moisture Content: Status after 5 years of Outdoor Exposure
2009 - IRG/WP 09-20401
The Danish Technological Institute is in co-operation with industry partners running a project aiming at predicting the service life of different wood protecting systems. The project focuses on examining the moisture reducing effect of different protecting systems for timber claddings and the ability of these to maintain the appearance of the surfaces, when the wood is used in service class 3 (EN 335-1 1992). A façade construction is exposed to weathering at the field test area of the Danish Technological Institute (near Copenhagen). In specific locations of the construction measurements of wood moisture are done by in-situ resistance moisture meters (Lindegaard and Morsing 2006). The aim is that the test should form the basis of evaluation of the maintenance requirements and the prediction of service life of the surface treatment and the wood/construction. At the moment 60 test racks are exposed. This study examines the data from the first five years of outdoor exposure using data from a test rack with a water-borne acrylic coating and a test rack with ICP coating for case studies. The moisture content data was converted into weekly average and weekly variation values which gave a deeper insight into the performance of the tested systems. The first was used to check for moisture build-up in the construction whereas the latter gave an indication of the gradual degradation of the coating itself, i.e. the degree of cracking. A linear tendency with time was found for all tested systems and the maintenance period could be estimated on the basis of data from only 2-3 years of outdoor exposure. The risk of biological degradation was evaluated using 20 % MC and 10 °C as a limit below which the risk was negligible. The annual accumulated time above this limit was used as an indication of the risk of biological degradation. Data was corrected for variation in weather exposure between the years and a fairly linear tendency in time was found, i.e. the risk of biological degradation was found to increase in time for all tested systems. Furthermore, other combinations of moisture content and temperature were used as limits enabling a more detailed view of the risk pattern. In general, it was found that measuring the moisture content in-situ in a façade construction of the suggested design can be a valuable tool in service life prediction. Within reasonable time, it is possible to obtain enough data to predict the service life of the construction in terms of maintenance period and the risk of biological degradation of the construction.
E Tang Engelund, B Lindegaard, N Morsing
Use of Confocal Profilometry to Quantify the Weathering of Wood
2009 - IRG/WP 09-20421
The methods that have been used to screen chemicals for their ability to prevent the weathering of wood involve assessing the loss in weight and tensile strength of treated wood veneers or measuring the rate of erosion of exposed and unexposed (masked) wood subjected to weathering. The erosion of wood during natural weathering occurs slowly and long exposure times are required to produce differences in erosion of masked and unmasked areas that can be quantified using optical microscopy. The erosion of wood can be accelerated using artificial accelerated weathering and by selecting low density wood species that erode quickly, but specimens still need to be exposed to accelerated weathering for 600 hours before reproducible differences in the erosion of masked and unmasked areas can be detected using optical microscopy. Accurate measurements of the erosion of materials can be made using confocal profilometry. We hypothesized that the use of confocal profilometry would make it possible to more accurately measure the erosion of wood during accelerated weathering and hence shorten the exposure time required to produce reproducible differences in the erosion of masked and unmasked wood in samples subjected to accelerated weathering. In this study we tested this hypothesis by using confocal profilometry to assess the erosion of western red cedar wood exposed to artificial accelerated weathering in xenon-arc and QUV weatherometers for 100, 250, 500 and 1000 hours. We also assessed whether erosion was affected by the size of the unmasked area exposed to artificial accelerated weathering. The erosion of wood specimens during artificial accelerated weathering increased with time as expected. Specimens exposed in the xenon arc weatherometer eroded significantly faster than specimens exposed in the QUV weatherometer. There was a positive correlation between the size of the unmasked area and the erosion of wood during artificial accelerated weathering. Our results confirm that confocal profilometry can accurately measure the erosion that occurs when western red cedar wood is exposed to only 100 (xenon arc) or 250 (QUV) hours of artificial accelerated weathering. We conclude that confocal profilometry is a faster, more accurate and less labour-intensive way of measuring the erosion of wood during accelerated weathering than optical microscopy. The implications of our findings for the development of surface treatments and preservatives that can maintain the appearance of wood exposed outdoors are briefly discussed.
Chunling Liu, P Evans
Continuous moisture measurement (CMM) to detect failure of moisture resistance
2009 - IRG/WP 09-20422
A wood coating system will fail to perform properly after a certain time of weathering. From that moment, the substrate is especially prone to fungal attack. Moisture plays a key role on weathering performance, wood protection efficacy and decay susceptibility of wood. Therefore, knowledge of the moisture dynamics of the applied wood protection is of significant importance in the prediction of the service life of the wood coating system. Furthermore, weather action (abiotic) and biological factors (biotic) change the impact of moisture on the wood coating system. In this regard, this research focused on detailed monitoring of the moisture fluctuations of eight wood coating systems during outdoor weathering using a CMM (Continuous Moisture Measurement) set-up. Simultaneously, weather data were recorded. Data processing comprised correlation analysis, PCA (Principal Component Analysis) and cluster analysis on the functional moisture content data. In addition a laboratory evaluation combining artificial weathering with a floating test is discussed to determine moisture characteristics in a reliable way. Finally, these techniques are evaluated as a tool for the estimation of service life.
I De Windt, J Van den Bulcke, J Van Acker
Variation in moisture content in field trials according to use class 3.2 conditions
2016 - IRG/WP 16-20580
Different test methods to determine the durability of wood in use class 3 (EN 335:2013) are available. Fungal degradation of wood requires liquid water. Different Standards (EN 335-1:2006; DIN 68 800:2011) specify the risk for decay with moisture content (mc) of above 20%. EN 335 (2013) does not specify moisture content but rather defined limited wetting conditions (use class 3.1) or prolonged wetting conditions (use class 3.2). However, in literature moisture content of approx. 30% (SCHMIDT 2005; HUCKFELD 2005) is mentioned as minimum requirement for attack. Earlier studies have shown, that moisture measurement based on electrical resistance of wood resulted in satisfying accuracy for MC between 15-50%. (Brischke et al 2008; Gellerich 2012, Meyer et al 2014). This paper reports on moisture measurement based on electrical resistance of native wood species as well as thermally modified and furfurylated pine in different moisture conditions according to use class 3.2 (EN 335:2014). The used test designs were the so named block test, rail test and decking test. For the evaluation of results, the number of days with mc above 20, 25, 30 and 35% was calculated. The results are evaluated with regard to wood species, mc and test design. All test designs resulted in moisture conditions above 25% for a longer period of time of native wood species in a measurement depth of approx. 20mm. Modified samples showed constantly lower moisture content than native species. However, over the test period of 24 months, the wood species displayed higher impact on moisture content than test design.
S Bollmus, A Gellerich, H Militz
Measurement of Cell Wall Moisture in Acetylated Radiata Pine Using Low-Field Nuclear Magnetic Resonance
2016 - IRG/WP 16-20583
Understanding the interaction of water with acetylated wood is necessary to explain how the protective mechanism of acetylation functions. Low-field nuclear magnetic resonance is one technique for assessing water in wood. Pinus radiata earlywood sapwood samples were acetylated to various weight percentage gains and then analysed with this method. Increased levels of acetylation showed significantly increased T2 relaxation times for free water, indicating that the free water is less restricted. This can be explained by the increase in hydrophobicity of the acetylated cell wall. The fiber saturation point (FSP) was determined using the signal from the cell wall water. The FSP of unmodified samples was 43 ± 2% moisture content and increased levels of acetylation significantly decreased FSP. At high weight percentage gain (~22%) the FSP was 16%, below the 20% threshold for fungal degradation to occur.
H G Beck, C A S Hill
Development of software to automate the quantification of the extent of penetration of treated wood
2021 - IRG/WP 21-20678
In Japan, Japanese Agricultural Standard (JAS) by the Ministry of Agriculture, Forestry and Fisheries and Approved Quality (AQ) by the Japan Housing and Wood Technology Center have established the penetration standard for treated wood. In our company, we measure the degree of penetration by either visual assessment or image processing. In the visual assessment, the degree of penetration is determined by calculation in our head. Although this method allows for quick measurement, it requires experience for accurate measurement. On the other hand, in the case of image processing, the degree of penetration is determined by measuring the area of coloration using some software e.g., Microsoft Paint, ImageJ. Although image processing is more time-consuming than visual assessment, it does not require the same experience as visual assessment. Since these two methods are not both quick and easy, we thought there was room for improvement. Therefore, the purpose of this study was to establish a quick and easy method for measuring the degree of penetration. To achieve this goal, we developed a new software program for measuring the degree of penetration. The program is written in Python and uses RGB color images. The procedure of the program is to identify the contour of the wood cross-section and classify each pixel as penetrated or unpenetrated. The number of pixels classified as penetrated is then divided by that of total pixels to calculate the degree of penetration, which is output to a spreadsheet automatically. As a result of using the software, we were able to measure the degree of penetration quickly and easily, and the accuracy was equivalent to that of the conventional method. In this paper, we explain the functions of the software and show an example of using the software to measure the degree of penetration of our products. This result is important because it will lead to the improvement of the quality control and the productivity of work.
Y Susa, D Watanabe, T Shigeyama, Y Sugai
Measurement of copper concentration in Cu-HDO treating solutions by handheld XRF
2022 - IRG/WP 22-20685
Copper based preservatives diluted in water dominate the wood preservative industry around the world. Periodically measurements and adjustments of the concentration of treating solutions must be performed as a part of the quality control at the treatment plant to achieve desired quality of the preservative treated wood. Many analytical methods are time consuming and must be performed under laboratory conditions, while others that are rapid and easy to apply at industry sites can be sensitive to impact from impurities, etc. The aim of this study was to evaluate handheld X-ray fluorescence (XRF) spectrometry as a tool for measuring copper concentration in CuHDO treating solutions. The material used in the study comprised samples of Wolmanit CX-8 (CuHDO) diluted in distilled water and samples from Wolmanit CX-8 treating solutions from Norwegian impregnation plants. All the preservative solution samples were analysed with a handheld Niton XL5 Plus XRF Analyzer. Atomic absorption spectrophotometry (AAS) was used as a reference method. The major advantages of portable handheld XRF spectrometry include: on-site immediate availability of analytical results, non-destructive analysis, a multielement capability, speed of operation and access to valuable/unique samples that otherwise would be unavailable or had to be transported to a laboratory for chemical analysis. The results from this study show that there is a good linear correlation with the XRF data and the corresponding laboratory results and that it is possible to use data measured with a handheld energy dispersive XRF-analyser for accurate calibrations and predictions of the copper concentration of treating solutions of Wolmanit CX-8.
P O Flaete