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Technique for monitoring absorption during a vacuum pressure process
1992 - IRG/WP 92-3696
A laboratory technique was developed and an apparatus constructed which allowed for the direct and continuous measurement and observation of volumetric uptake of water-borne preservative into wood samples throughout a controlled vacuum-pressure treatment process. Fractional filling of void space was calculated. Graphing (fractional saturation) against time allows prediction of optimum cycle lengths with respect to achievable saturation values. Treatability evaluations using this technique were carried out on heartwood samples of six Malaysian hardwood species, kapur, kempas, keruing, punah, rubberwood, simpoh and on sapwood samples of Scots pine as a control. Generally the graphs exhibited two quasi-linear zones showing rapid initial absorption followed by slow absorption over a long period.
A J Pendlebury, J A Petty


A summary of tests and practical experiences with the Pilodyn wood testing instrument
1980 - IRG/WP 282
This paper presents a summary of the reports, tests and practical experiences with the Pilodyn wood tester not only, however, concerning poles but also in other fields such as standing trees, sawn timber etc. The principle of the Pilodyn is a spring-loaded pin which is fired into the object and the depth to which the pin penetrates is correlated to physical and mechanical properties of the object.
H Friis-Hansen


Decay, decayed wood and the Shigometer
1980 - IRG/WP 281
A L Shigo


Studies on the permeability of Norway spruce (Picea abies)
1987 - IRG/WP 2295
It is well known that the bordered pits play a dominating role for liquid transport in softwoods. The mechanism behind pit aspiration during drying or heartwood formation seems to be well understood. The reason why the fixation of the membrane (torus) to the pit opening remains almost irreversible is, however, still unclear. A technique has been developed combining so-called "solvent exchange drying" with scanning electron microscopy. In this way the pit system can be "frozen" and the number of pits in aspiration can be determined. The technique has been used to widen the understanding of pit aspiration. It has also been used to follow pit aspiration during air drying and in connection with efforts to pit aspirated pits by different physical and chemical methods.
I Johansson, K Nordman-Edberg


Preservative treatment of Gollah cane (Daemonorops jenkinsiana) by soaking method
2001 - IRG/WP 01-40197
The feasibility of preservative treatment of gollah cane (Daemonorops jenkinsiana (Griff.) Mart.) by soaking method was tested in the present study. Cane samples of 1m, 2m and 3m long were soaked with 10% borax and boric acid solution. The study revealed that adequate dry salt retention (DSR) in the above samples could be obtained in 3 days, 4 days and 5 days of soaking, respectively. Within these periods the above rattan samples retained 17.77 kg m-3, 14.97 kg m-3 and 15.00 kg m-3 of dry salt. The DSR values obtained were much higher than those of the specification (4 kg m-3) of Indian Standard. Dry cane (12.87% m.c.) samples up to 3m - 4m long could be treated easily within 5 days, but the same dimension of green (150% m.c.) samples needed 8 days. DSR values of air-dried samples were about 7 times higher than that of the green samples.
M Younus-uzzaman, K Akhter, M H Chowdhury


The effect of initial moisture content on wood decay at different levels of gaseous oxygen concentration
1999 - IRG/WP 99-10316
The influence of initial moisture content on wood decay at different levels of atmospheric oxygen concentration was studied. Three fungi, Coriolus versicolor a white rot, Coniophora puteana a brown rot, and Chaetomium globosum a soft rot, were chosen. The mycelia of the fungi were inoculated on mini blocks of Fagus sylvatica (beech) and Pinus sylvestris (Scots pine). Incubations were under four levels of oxygen concentrations (1, 5, 10, and 21%) at 22°C. It can be summarised that in low oxygen concentrations, increase of the moisture content had a negative effect on the wood decay process in both wood species when exposed to C. versicolor and C. puteana Basidiomycetes). In air, the effect of initial moisture content on wood decay by these fungi corresponded to the fungi characteristics and the wood species. When used C. globosum (soft rot) as coloniser, increasing moisture content generally caused weight losses to be increased (specially in beech). However, when in wood blocks the moisture content was increased, more sporulations of C. globosum were also observed on wood samples.
S M Kazemi, D J Dickinson, R J Murphy


Gelatin encapsulated fumigants for wood fumigations: Current research status
1985 - IRG/WP 3336
The fumigants chloropicrin (trichloronitromethane) and methylisothiocyanate (MIT) were encapsulated in gelatin as an alternative to liquid fumigant treatments for control of decay fungi in wooden utility poles. Gelatin-encapsulated MIT was stored for over 2 years under dry conditions without significant fumigant leakage. Gelatin encapsulated MIT and chloropicrin were released from capsules when placed in wood above the fiber-saturation point, although capsules were more permeable to MIT than chloropicrin. In field treatments, the addition of small quantities of water along with capsules was sufficient for fumigant release. Encapsulated MIT and chloropicrin treatments effectively reduced decay fungus populations in Douglas-fir utility poles.
A R Zahora, M E Corden, J J Morrell


Moisture correction for ultrasonic MOE measurements above fibre saturation point in Scots pine sapwood
2006 - IRG/WP 06-20333
There is a high correlation between methods for dynamic modulus of elasticity (MOEdyn) and static modulus of elasticity (MOEstat). MOEdyn methods have been found sensitive to detect early stages of decay and may be seen as an option for non-destructive wood durability testing. As the MOEstat measurements do not change after reaching the fibre saturation point, the uncorrected MOEdyn data from ultrasonic pulse excitation method provides increasing values after fibre saturation. This is due to the effect of free water in the cell lumen on ultrasonic waves. The aim of this study was to make a moisture calibration for the MOEdyn ultrasonic pulse excitation method using Scots pine (Pinus sylvestris L.) sapwood samples. MOE was measured at five different moisture levels. Three different MOE test methods were used: MOEdyn using ultrasound and vibration excitation and the traditional MOEstat. Sound Scots pine sapwood samples treated with two copper-containing wood preservatives and two chitosan solutions were evaluated, using untreated sapwood samples as control. In this study a correction value ("k") was calculated based on data from different moisture levels for water saturated samples using four different wood treatments and control. By measuring MOEdyn ultrasonic at wood moisture contents just below fibre saturation point, a minor effect of incipient water accumulation in the wood matrix was detected. Wood treatments influence the "k" value, and a "k" value needs to be calculated for all wood treatments when measuring MOEdyn ultrasound above fibre saturation. All the three MOE test methods in this study are applicable for all wood moisture levels as long as a "k" value is calculated for MOEdyn ultrasound above fibre saturation.
E Larnøy, G Alfredsen, H Militz


Correlation of %Acetyl and Fiber Saturation in Acetylated Southern Pine Boards
2012 - IRG/WP 12-40598
Wood acetylation represents a chemical modification that increases the hydrophobicity of wood. The level of acetylation in the wood structure determines the extent of hydrophocity with higher levels providing reduced moisture affinity. Due to the reduced hygroscopic nature of acetylated wood, performance features such as dimensional stability, resistance to termites, and resistance to rot and decay fungi are significantly improved. The fiber saturation point (FSP) represents the theoretical moisture content at which wood cell walls are completely saturated with water and no additional water can be absorbed into the wall structure as bound water. The fiber saturation point of acetylated wood is reduced as compared to unacetylated wood also due to its increased hydrophobicity. In this work, the fiber saturation point of a series of 30.5 cm x 14 cm x 2.54 cm acetylated Southern Pine radius edged deck boards with varied levels of acetyl was determined by measuring the width as a function of moisture content. It was found that the fiber saturation point of acetylated wood correlates with the level of acetyl in the wood substrate. A linear relationship is found between these two factors with increasing levels of acetyl providing a reduction in fiber saturation point. The method used to determine the fiber saturation point in this work provides consistent results with that previously determined via an alternate technique. Unacetylated Southern Pine deck boards were also studied in this work and revealed fiber saturation points consistent with prior determinations in the literature and fitted the relationship between acetyl level and fiber saturation point.
J Dickerson, E Cwirko, J Allen


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