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Application of radio frequency heating to accelerate fixation of CCA in treated round-wood
1999 - IRG/WP 99-40133
The potential of radio frequency heating to accelerate the fixation of chromated copper arsenate (CCA) in treated round-wood was assessed. Pre-dried Douglas-fir and western red cedar round-wood sections were pressure treated with CCA in a pilot plant retort, after which they were placed individually in a pilot radio frequency (RF) chamber. Based upon the color reaction of chromotropic acid with hexavalent chromium and the quantitative assessment using diphenyl carbazide, fixation was achieved in less than 6 hours. During heating, the temperature at various locations inside the pole sections was monitored by fiber-optic thermocouples. The moisture profiles before, and after fixation, were also recorded. Further studies will examine other benefit of RF heating, including a) sterilization, and b) rapid drying of round-wood with minimum check formation.
Fang Fang, J N R Ruddick

Corrosion of zinc-coated nails used with preservative-treated western red cedar shakes in service
1982 - IRG/WP 3197
The corrosion of metal fasteners used with certain wood species and with preservative-treated woods can be a serious problem. The chemical reactivity of western red cedar (Thuja plicata Donn) extractives to iron and copper is well documented and wood preservative treatments containing copper, chromium, and/or ammonium hydroxide can be expected to similarly attack some metals. This problem is compounded when red cedar is treated, and, such treatments with CCA and ACA have become customary in current efforts to extend the service life of shingles and shakes. Present recommendations for shake and shingle roof applications specify the use of hot-dipped zinc (iron) or aluminium nails. However, the use of nails made of stainless steel or other alloys of greater cost is advised with preservative-treated wood products.
R S Smith, E L Johnson, A J Cserjesi

Flow charts for termite and decay tests to determine the natural durability of Japanese cedar (Cryptomeria japonica D. Don)
2008 - IRG/WP 08-20385
This paper deals with the experimental flow charts that were used for determination the effects of fungal decay and termite attack on Sugi heartwood during the course of the study of “Comparative studies of natural durability of Japanese cedar (Cryptomeria japonica D. Don) among the geographic cultivate”, which was carried out by Usta et al (2006).
I Usta, S Doi

Evaluation of Barrier Wrap Systems after 71 Months of Exposure
2013 - IRG/WP 13-40631
A 71 month study of the performance of booted samples in ground contact was conducted in AWPA hazard zone 4. Data indicated that excellent performance of wrapped systems, even over untreated wood, could be obtained. Instances of decay colonization or termite attack could all be attributed to some breaking of the integrity of the barrier system. Good performance for treatment below ground contact threshold was demonstrated.
H M Barnes, M G Sanders, G B Lindsey, C McIntyre

Termite-tunnels formation on the surface of termite-resistant wood species in field sites
2001 - IRG/WP 01-10400
In this report, termite-tunnels formation by the subterranean termite, Coptotermes formosanus Shiraki on the surface of termite-resistant wood species, namely, Hinoki (Chamaecyparis abtsu), Yoshino Hinoki (Chamaecyparis abtsu), Miyazaki Hinoki (Chamaecyparis abtsu), Hiba (Chamaecyparis abtsu) and Japanese cedar (Cryptomeria japonica) was conducted in field sites. Westernhemlock (Tsuga heterophylla), Douglas- fir (Pseudotsuga taxifolia) and Ryukyu pine (Pinus luchuensis) were used as the control. 62 The termite-resistant woods species were classified either as heartwood timber (H) or sapwood timber with a heartwood center (S) and also classified based on their prefecture of origin. Otherwise, the termite- resistant wood species for the termite test were examined in using the forms on the surface of all the termite-resistant wood species by the subterranean termite, Coptotermes formosanus Shiraki. It was found that even for termite-resistant wood species treatment with preservative chemicals is required.
Y Kadekaru, K Kinjo, S Yaga

Black Stain of Western red-cedar by Aureobasidium pullulans and its Relationship with Tropolone Depletion
2005 - IRG/WP 05-10564
Western red-cedar is valued for its natural durability conferred by fungicidal tropolone chemicals. However, weathered surfaces of WRC products are still susceptible to ‘black stain’ caused by fungi such as Aureobasidium pullulans. The effect of weathering on the tropolone content of heartwood was characterized and correlated with the ability of this fungal species to colonize the same weathered surfaces. UV plus water spray severely reduced tropolone content but did not lead to increased fungal colonization compared to un-weathered wood. When WRC was treated with UV only, the tropolone content was less affected but the fungal colonization increased significantly. A.pullulans exhibited high tolerance to the tropolone β-thujaplicin in vitro; thus loss in tropolone content may not be required for colonization. In addition to UV resistance from melanization and ability to use lignin breakdown products as a carbon source, resistance to tropolones may confer considerable competitive advantage to A.pullulans growing on WRC exposed to weather. The application of water spray most likely washed away products of lignin photo-degradation, leaving the wood surface void of accessible carbon sources which resulted in decreased colonization.
R Chedgy, R Daniels, P I Morris, C Breuil

Fumigation of New Zealand grown western red cedar for export markets
2001 - IRG/WP 01-30262
The objective of this study was to demonstrate that methyl bromide fumigant penetrates into the centre of western red cedar (Thuja plicata L.) timber to meet the standard for export markets. Kiln dried western red cedar was used and a cavity (50x 30 x 13mm3) was prepared into the centre of each sample board (500 x 200 x 26 mm3 thick). An absorbent sachet used in industry for cross checking that the concentration of methyl bromide meets the standard during fumigation of export commodities was then inserted into the cavity. Two sample boards with individual sachets separated by aluminium foil and positioned at 13 mm below the wood surfaces, were then glued together. After curing of the glue, an aluminium tape was used to seal the four edges of the sample to prevent penetration of methyl bromide through the boards' edges. Fumigation was performed for 24 hours in the laboratory and also in a commercial environment using 80g of methyl bromide/m3 of wood prior to the cross checking of sachets. The results of this study demonstrated penetration of methyl bromide into the centre of kiln dried western red cedar (26 mm thick) in sufficient quantity to meet the specification for export to overseas markets.
B Kreber, G Durbin, D Wilson

Step-wise pressure process for reducing surface roughness in Japanese cedar timber
2003 - IRG/WP 03-40256
Sixteen dried sawn-timber (10.5 x 10.5 x 360 cm) were cut into half. The half of them was treated by step-wise pressure process with 2.5 MPa maximum, and the other half was treated by conventional pressure process with 2.5 MPa maximum. Average DDAC preservative absorption was 461 kg/m3 in the former and 525 kg/m3 in the later. Surface roughness was expressed as the profile element height of collapse on the surface of treated timber. The maximum profile element height was 1.10 mm in the former and 3.10 mm in the later. The average value height ranged between 0.35 mm and 0.58 mm in the specimens by conventional process, and 0.19-0.24 mm in those by step-wise process. Step-wise pressure treatment reduced the surface roughness but also reduced preservative absorption.
K Yamamoto, M Nozoki

Effect of substrate type and moisture requirements in relation to colony initiation in two carpenter ant species
1999 - IRG/WP 99-10320
Conditions necessary for optimal colony initiation or the rate of initial colony expansion by early brood in the carpenter ant species Camponotus modoc and C. vicinus on various substrates conditioned to different moisture contents were studied. Camponotus modoc and Camponotus vicinus queens were placed in Douglas-fir, western red cedar and Styrofoam® blocks conditioned in sealed chambers at 70% or 100% relative humidity. Chambers were periodically monitored for changes in substrate weight, numbers of eggs, larvae, pupae, and worker ants produced. Brood counts produced after thirteen weeks were used to assess the effects of substrate and moisture content on colony initiation. Queens of C. vicinus in Douglas-fir and Styrofoam® produced worker numbers that did not differ significantly with moisture content. However, the number of colonies initiated for C. modoc did significantly differ with moisture content. The results indicate that colony initiation in C. vicinus is less sensitive to moisture content then C. modoc for Douglas-fir and Styrofoam®. No differences were found between moisture contents for ant queens in western red cedar, due to a lack of colony initiation. These results suggest that cedar was detrimental to the development of early brood in both ant species.
M E Mankowski, J J Morrell

Bioefficacy of Cunapsol® treated western cedar and southern yellow pine
1996 - IRG/WP 96-30120
Western red cedar and southern yellow pine sapwood were dip treated with a new formulation of waterborne copper naphthenate (Cunapsol®) which complies with VOC regulations. Cunapsol dip treated samples were oven dried at 50°C for 48 hours and then water leached for two weeks. Decay resistance and leachability of preservatives from dip treated specimens were evaluated according to AWPA (American Wood Preservers' Association) standard methods. CCA type C, ACQ type D and oilborne copper naphthenate were used for comparison purposes. Test results suggested that copper loss during leaching of dip treated samples is higher with copper amine based solutions than with CCA type C or oilborne copper naphthenate. Weight loss of treated samples was negligible suggesting that a copper retention of 1.70 ± 0.20 kg/m³ (0.10 pcf) from waterborne copper naphthenate offers adequate protection to western cedar and southern yellow pine.
D P Kamdem, M H Freeman, T L Woods

Comparative studies of natural durability of Japanese cedar (Cryptomeria japonica D. Don) among the geographic cultivates
2006 - IRG/WP 06-10592
Variation of natural durability of Japanese cedar (Cryptomeria japonica D. Don) (also known as Sugi) was investigated by accelerated tests for decay (Fomitopsis palustris (Berk. et Curt.) Murr.) and termite (Reticulitermes speratus Kolbe) attacks on 13 clones of Sugi trees from Kyushu-Okinawa Region (Fukuka, Ooita, Saga, Miyazaki, Kagoshima). For this purpose, 57 twenty-five years old Sugi trees of various land races were collected from a clonal trial in Kyushu, Ehime Prefecture, Japan. The deterioration by fungal decay and termite attack was determined as the percentage of mass loss of Sugi heartwood. It was mainly observed that the trial clones were individually stronger on fungal decay than termite attack, and the mass losses in either case appeared to vary between the clones. The ranges of mass loss values caused by termite attack were very close to each other within each clone with the lower standard deviation, whereas the actual values of mass loss after fungal decay created large range between each other in most of the clones with the higher standard deviation. Examination of the results reveals that the northern clones from Kyushu-Okinawa Region are more resistant.
I Usta, K Takata, S Doi

Molecular characterization of M’jej, decaying agent of cedar forests in Morocco
2006 - IRG/WP 06-10593
Cedar wood is well appreciated since thousand years even though its economical importance is limited because of its world distribution restricted to some Mediterranean countries and Himalaya. The most important species, Cedrus atlantica have its biggest population in Morocco (130 000 ha) where it is submitted to fungal diseases. Among them, the locally named “M’jej” reduced notably saw mile harvest, with about 12 % infection rates. “M’jej” induced fibrous rot of heartwood. Among the various genera and species described as responsible for M’jej, all are synonyms of Phellinus chrysoloma or P. pini. Identified according to fruit bodies morphological, anatomical and ecological characters, both species would be responsible for M’jej. Molecular characterisation based on samples collected from infested trees and the comparison with reference data base sequences allowed us to evidence very close taxonomical relationships between these two species suggesting their putative synonymy.
A Zaremski, S Bakkali-Yakhlef, C Chaintreuil, Y Abbas, Y Prin, M Abourouh, M Ducousso

Corrosion of metal fasteners in contact with copper preservative treated wood
2007 - IRG/WP 07-20370
The corrosion rates of metal fasteners in contact with alkaline copper quat (ACQ) treated wood with or without commercially available water repellent was compared to that of cedar. In this experiment, fasteners were sandwiched between two pieces of treated wood and exposed to a humid environment at a slightly elevated temperature. The use of a “sandwich” design allowed periodic examination of the metal fasteners, which were exposed to the typical chemical loading found at the surface of treated wood. During the experiment, visual observation, weight loss, and diameter loss were used to evaluate the corrosion rate. A one-way ANOVA analysis, confirmed that Stainless Steel 304 provided the best corrosion resistance and a common bright nail provided the worst corrosion resistance, in contact with either copper preservative treated wood or western red cedar. However, the performance of individual coated fasteners in copper preservative treated wood and western red cedar were insignificant on corrosion rate (P<.0001) at the 5% significance level. In a comparison of the wood samples, copper preservative treated wood are approximately two times more corrosive to metal fasteners compared to western red cedar.
BaekYong Choi, J N R Ruddick

Development of a Weatherometer to Accelerate the Surface Checking of Wood
2008 - IRG/WP 08-20388
There is significant interest in developing preservatives that are better at preventing wood from checking. Currently, however, there is no accepted test methodology for accelerating the development of checks in wood samples so information on the effectiveness of treatments at restricting checking can be obtained more quickly. This paper describes the development of a new type of weatherometer (Accelerated Check Tester) and associated weathering cycles to accelerate the surface checking of wood. The device permits the testing of realistic-sized decking board samples that are oriented horizontally and restrained by fixings. It uses computer-controlled water spray and infra-red heating systems to expose samples over a 5 day period to wetting and drying cycles. Desiccated air is also blown across the surface of samples to further increase the effectiveness of the drying cycle. The Accelerated Check Tester operated continuously and trouble-free for 24 weeks during an experiment, which examined the effect of different weathering cycles on the checking of southern pine and western red cedar decking samples. Samples exposed in the Accelerated Check Tester developed large numbers of checks, some of which were quite big, particularly those in southern pine samples. Weathering cycles that increased the severity of drying by increasing drying time or temperature did not significantly increase checking. Similarly, the inclusion of a freezing step in the weathering cycle had little effect on checking. In contrast, samples subjected to a cycle that included exposure to ultraviolet light developed significantly more and larger checks than samples subjected to any of the other cycles. Checking was much more pronounced in southern pine samples than in western red cedar samples. The Accelerated Check Tester should be a very useful tool for obtaining information on factors that affect the checking of wood. Furthermore, it could also allow companies developing wood preservatives and associated water repellent additives to rapidly obtain information on the ability of treatments to restrict checking and so shorten the development time for new wood protection systems.
R Ratu, P D Evans

Surface Characteristics of Southern pine treated with Eastern red cedar oil
2008 - IRG/WP 08-40393
Treatment of wood with various chemicals play an important role on their surface characteristics including as roughness and hardness for further processing such as finishing and machining. The objective of this study is to evaluate surface roughness of Southern pine (Pinus taeda L.) treated with oil extracted from eastern redcedar (Juniperus viginiana L.). Both tangential and radial surfaces of pine samples were treated two non-pressure methods, namely brushing and cold soaking in the oil. Surface quality of the samples were determined using a stylus technique at the end of each type of treatment. Three roughness parameters, average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Rmax) were used for the quantification of treated surface of the samples. Janka hardness method was also employed to evaluate if there was any effect of treatment on hardness of the samples. Average Ra values of 5.42 µm and 3.67 µm were found for tangential and radial surfaces of 24 hrs soaked samples, respectively. Roughness parameters taken from the surface of control and treated samples did not show any significant difference from each other at 95% confidence level. Average Janka hardness value of radial samples was 2.5 times higher than that of tangential. However, hardness values of control and treated samples also did not show significant difference from each other at above confidence level. Based on the findings of this preliminary study eastern redcedar oil could be considered as alternative treatment chemical for wood products without having any adverse effect on their surface roughness and hardness.
S Hiziroglu

Effects of bleaching process on the roughness values of wood surfaces of Lebanon cedar (Cedrus libani A. Rich.) and Black poplar (Populus nigra L.) using NaOH (sodium hydroxide), H2O2 (hydrogen peroxide) and Ca(OH)2 (calcium hydroxide)
2008 - IRG/WP 08-40403
Technical progress in the wood industry has been rapid in recent times. In this case, the quality assurance of the consumer products aligned with aesthetics value appears as one of the most important parameters. Because of the outer appearance of goods exert an effect on customers, interest in production of high quality surfaces of wooden commodities has increased essentially based on the surface smoothness (and/or the surface roughness of wood) aiming to reach the customer-oriented quality criteria. An aesthetics behaviour is being more influenced than the functional situation of the merchandise when the customers making the decision to buy wood products. It has been well estabilished that some of the properties of wood material (i.e. density, porosity, moisture content, fiber directions), and the wood machining process and its conditions (i.e. kinematics of the cutting process, wood sanding process) make the surface smoothness of wood problematic. There is a lack of information about the effects of bleaching process (i.e. one of the special technical ways to increase the aesthetics of wood products) on the smoothness of wood surfaces despite numerous reports published on the machining tools and the cellular structure of wood. In this study, therefore, effects of bleaching process on the surface roughness of wood was investigated for Lebanon cedar (Cedrus libani A. Rich.) and Black poplar (Populus nigra L.) using the bleaching chemicals NaOH (sodium hydroxide), H2O2 (hydrogen peroxide) and Ca(OH)2 (calcium hydroxide) by the two prescriptions with or without calcium hydroxide.
I Usta, E Aydinlar

Improvement of the Fungal Resistance of Japanese Cedar by the ThermoWood Process
2008 - IRG/WP 08-40422
The effect of the ThermoWood Process on sapwood of the Japanese cedar, Cryptomeria japonica, was investigated. Seven matched specimens were cut from a sapwood board of Japanese cedar and subjected to thermal treatments according to the ThermoWood Process. The decay resistance and chemical and physical properties of the treated specimens and untreated specimen were investigated. The decay test was carried out according to the Japan Industrial Standard K1571-2004. The specimens were cut to the size of 2 (R) ? 2 (T) ? 1 (L) cm or 2 (R) ? 2 (T) ? 10 (L) cm and subjected to the laboratory decay test and the fungus cellar test, respectively. The results of both tests clearly indicated that the ThermoWood Process at temperatures above 210 °C effectively increased the decay resistance of Japanese cedar sapwood. Mass loss was less than 13% in the sapwood treated at 220 °C for 2.5 hours, but was about 50% in the untreated specimens. Thermal treatments at higher temperature and for a longer period improved the decay resistance. No mass loss was found in the specimens treated at 237.5 °C for 5 hours. A similar tendency was observed in the fungus cellar test. The average decay rate of the untreated sample reached 4.6% after exposure for 0.6 year in the fungus cellar while that of the samples treated at 237.5 °C for 5 hours was still 0%. Determination of holocellulose contents suggested that the percentage of holocellulose was a good index for assessing the degree of thermal treatment and the level of decay resistance.
I Momohara, T Morita, S Shouho, A Yamaguchi

Field Tests of naturally Durable North American Wood Species
2008 - IRG/WP 08-10675
There has been little field test performance data published on North American naturally durable species in general, and no published data on second growth material in particular. Yellow cedar (Callitropsis nootkatensis), western red cedar (Thuja plicata), eastern white cedar (Thuja occidentalis), and three wood species reputed to be moderately durable were installed in ground-contact (stakes) and above-ground (decking) field tests at test sites in British Columbia and Ontario, Canada and Florida and Hawaii, USA between the Fall of 2004 and Spring 2005. Where possible old growth and second growth material, with and without sapwood, were obtained and used in the testing. Results from ground-contact field stakes and above-ground mini-decks after 3 years exposure are presented. The test site with the fastest ground-contact decay rate was Florida. The fastest above-ground decay rate was seen in Hawaii. In general, yellow cedar was the most decay resistant, followed by the other two cedar species, then the three other species. There was no appreciable difference in decay resistance between heartwood samples from old-growth and second-growth western red cedar, yellow cedar, and larch (Larix occidentalis).
P E Laks, P I Morris, G M Larkin, J K Ingram

Effect of Preservative Treatment on Fungal Colonization of Teak, Redwood, and Western Red Cedar
2009 - IRG/WP 09-20404
Fungal flora present in preservative treated samples or non-treated samples from sapwood and heartwood of teak, western red cedar, redwood, and southern yellow pine was assessed after 6 to 18 months of exposure near Hilo, Hawaii. The objectives were to compare fungal composition and diversity between treated and non-treated samples, and to examine the use of molecular techniques for assessing fungal community structure in a ground-proximity-test located in Hilo, Hawaii. Fungi were recovered in culture after 6, 12, or 18 months, yielding 178 unique DNA sequences that represented 85 taxa. Sequence data from the nuclear ribosomal internal transcriber spacer (ITS) region showed the taxa represented 56 ascomycetes, 17 basidiomycetes, 1 zygomycete and 10 unknowns. Basidiomycetes were mainly found in samples treated to the lowest biocide concentrations or non-treated samples, while there were no consistent isolation patterns with ascomycetes. Overall, treatment did not appear to affect community structure. Our results highlight (i) the need for caution in designating taxonomic units (species) based on culture or ITS BLAST matches, (ii) the utility of fungal culturing followed by molecular identification but the limitation of the sampling process, (iii) the remarkably high diversity of fungi colonizing wood in a ground proximity test under these tropical conditions.
Y Cabrera, C Freitag, J J Morrell

Antifungal Activities of Three Supercritical Fluid Extracted Cedar Oils
2009 - IRG/WP 09-30501
The antifungal activities of three supercritical CO2 (SCC) extracted cedar oils, Port-Orford-cedar (POC) (Chamaecyparis lawsoniana), Alaska yellow cedar (AYC) (Chamaecyparis nootkatensis), and Eastern red cedar (ERC) (Juniperus virginiana L), were evaluated against two common wood decay fungi, brown-rot fungi (Gloeophyllum trabeum) and white-rot fungi (Trametes versicolor). The statistical analysis showed that SCC extracted cedar oils had higher antifungal activities othan hexane Soxhlet extracted cedar oils against both white-rot fungi and brown-rot fungi. In vitro studies showed that AYC oils showed the strongest antifungal activity among the three cedar wood oils, followed by POC oil and ERC oil.
Tianchuan Du, T F Shupe, Chung Y Hse

A comparison of the corrosion of alkaline copper and micronized copper treated wood
2010 - IRG/WP 10-40515
With the replacement of chromate copper arsenate (CCA) by alkaline copper wood preservatives, there have been reports of increasing corrosion of metal fasteners and connectors in contact with treated wood. This may be explained by the presence of more mobile copper in the treated wood. One novel industrial response has been to develop a wood preservative based on an aqueous solution containing suspended basic copper carbonate and a co-biocide. This micronized copper preservative relies on the basic acidity of wood to release the copper which can complex with the wood components. As a consequence of the lower amount of mobile copper, the degree of corrosion should be significantly lowered, compared to the corresponding alkaline copper preservatives. The objective of this study is to examine the relative corrosiveness of micronized copper and alkaline copper treated wood to determine whether a significant reduction in corrosiveness is obtained. The interim results of the study have confirmed a significant reduction in the degree of corrosion on hot dipped galvanized fasteners as well as a lower rate of corrosion on bright (or common iron) fasteners. The levels of the corrosion of the micronized copper treated wood were similar to those observed for western red cedar, a durable wood that has been used in the past for decks and fences in British Columbia.
M Kofoed, J N R Ruddick

Extractives in Norwegian-Grown and North American-Grown Western Redcedar and Their Relation to Durability
2012 - IRG/WP 12-10762
The extractives responsible for the natural durability of western redcedar (WRC) are not well understood. Recent work by the Norwegian Institute of Wood Technology and the Norwegian Forest and Landscape Institute has evaluated the natural durability of Norwegian wood species and reference species, including Norwegian-grown WRC and North American-grown WRC, in a series of decay tests. The availability of retained samples from these tests presented an excellent opportunity to compare the extractives contents of North American and Norwegian grown-WRC, and to correlate field test decay data and extractives content. The North American-grown WRC contained much greater concentrations of extractives than the Norwegian-grown WRC evaluated in this test. However, despite these differences, performance in the EN 252 stake test in Sørkedalen was only marginally better for North American-grown WRC. Both sets of samples were comparatively low in an as yet uncharacterized compound previously associated with decay resistance. However, there were not enough data to thoroughly examine the correlations between extractives and durability data in this material.
R Stirling, P O Flæte, G Alfredsen, P I Morris

The effects of impregnation with secondary metabolite extracted from Ipe on durability of Japanese cedar and beech wood
2013 - IRG/WP 13-30618
Ipe wood is known for its high durability; it has been widely used in exterior structures that are exposed to the weather. In this paper, to increase the durability of less durable wood, Japanese cedar and beech specimens were impregnated with a secondary metabolite from Ipe. In a previous study, secondary metabolites extracted by a Soxhlet extraction method showed antifungal properties. Therefore, to establish a simpler and more economical extraction method, we investigated extraction by soaking with a solvent. Then, non-durable wood specimens were impregnated with extractives and examined by accelerated fungal tests. After exposure to fungal attack with wood-decaying fungi such as Fomitopsis palustris, Japanese cedar specimens exhibited less than 3% mass losses. Extractives retention after weathering treatment of Japanese cedar and beech specimens were 86.1% and 59.1%, respectively. Moreover, both specimens demonstrated bulk coefficients that suggested the permeation of extractives into cell walls. These results indicated that the extractives of Ipe have high compatibility with cell walls of other types of wood, and can transfer durability against wood-decaying fungi.
T Iida, R Konuma, K Kawarada

An Overview of Western Red Cedar as a Wood Pole Species
2014 - IRG/WP 14-10815
This paper reviews the characteristics of western red cedar, with particular emphasis on its use in utility poles. Western red cedar naturally grows primarily in British Columbia, Alaska, Washington, Oregon, California, Idaho and Montana. Compared to other commercial softwoods it has low density, increased corrosivity, weaker mechanical properties, high dimensional stability, and high natural durability. The natural decay and termite resistance of western red cedar’s heartwood is due to the presence of extractives. These include thujaplicins and a series of lignans, the most abundant of which is plicatic acid. The role of these extractives in the durability of wood in service is still not fully understood. The natural durability of western red cedar heartwood increases from the pith to the heartwood/sapwood boundary and from the top of the tree to the base. Although younger trees are being harvested today than in previous years, the wood produced today remains durable. Approximately 155,000 WRC utility poles are produced annually in the United States and Canada. Most of these are pressure-treated with preservatives to maximize service life. However, thermal treatments of the full-length of the pole, or of just the butt, may also be used.
M H Freeman, R Stirling

Reducing Extractives Stain in Western Red Cedar Sidewall Shingles
2014 - IRG/WP 14-30654
One of the aesthetic challenges that western red cedar shingles face is extractives redistribution stain, particularly in unpainted sidewall applications. Dip and pressure treatments with a mixture of quaternary ammonium compounds and alkyl amine oxides were investigated for their ability to prevent this stain. After nine months of exposure in Vancouver, extractives stain was present on nearly all untreated shingles, but was greatly reduced in incidence and intensity on both the dip- and pressure-treated shingles. Longer-term potential benefits (increased durability) and risks (accelerated weathering) of these treatments should be investigated.
R Stirling

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