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Natural durability transfer from sawmill residues of white cypress (Callitris glaucophylla). - Part 3: Full penetration of the refractory sapwood of white cypress
2000 - IRG/WP 00-40167
The heartwood of white cypress, Callitris glaucophylla, is renowned for its termite resistance and durability against decay. The sapwood, which can represent up to 30% of log volume, is non-durable and refractory to conventional preservative treatment. Previous work ascribes the lack of permeability to oily deposits within tracheids and ray cells. Environmental scanning electron microscopy was used to investigate ultrastructural aspects of sapwood permeability. Several pre-treatment processes to improve permeability were tested with limited success. Solvent drying allowed preservative penetration but damaged the structure of the timber. Neither, long term water soaking nor an oscillating pressure/vacuum cycle had any effect on porosity to water-borne treatments. Through extensive modifications to a standard VPI process we can now repeatedly achieve full penetration with organic solvent-based wood preservative solutions into white cypress sapwood. Effects of this process on the strength of the timber are being evaluated. Work is continuing as to the most effective and efficient treatment schedule and the latest results will be presented at IRG 31.
M J Kennedy, L M Stephens, M A Powell

Methodology challenges in developing a transfer of natural durability from sawmill residues, illustrated by experiences with white cypress (Callitris glaucophylla)
2000 - IRG/WP 00-20203
The transfer of durability-conferring extractives from durable to non-durable wood has been accomplished often, but usually as an educational exercise rather than as a commercially oriented process. In the latter environment, many factors previously overlooked become vitally important. How to study them, in the absence of well-developed methodology and given the shorter timeframes being demanded by industry research funding organisations, presents real challenges. These challenges will be illustrated by experiences with the development of such a process for the 'waste' durability components of white cypress. Factors to be considered include: identification of active components; quantification of their individual and collective activities against target organisms; optimisation of source material handling, storage and extraction techniques; extract standardisation and batch-to-batch reproducibility; compatible yet cost-effective carriers for the actives into treated wood; effects on durability and other wood properties such as strength and handling safety; regulatory obstacles including acceptance into wood preservation standards; and quality control methods for penetration and retention of the treated product.
M J Kennedy, M A Powell

Analysis of degradation observed on ancient wooden objects buried underground
2001 - IRG/WP 01-10403
Ancient wooden objects were sometimes excavated from the moat of mounded tombs in Japan. Such wooden objects were in the shape of a sunshade, bird, shield, pole, yugi(a bag that holds arrows) among others. Archaeologists discussed the usage of such shaped objects, but no one could clearly explain their use. Some objects were observed using an ordinary microscope. Deterioration by bacteria was found in all parts of the objects. This showed that all the objects had been in water or in heavily water-logged earth. Heavy degradation by soft rot fungi was found at the bottom of the shield and pole shaped objects. It is thought that at one time these objects were erected and partly buried in the ground. A lot of hyphae were found at the bottom of another shield and yugi shaped objects. A small amount of hyphae were additionally found at the top of these objects. These are thought to have been placed on top of the ground. From these results, it is supposed that at the first stage, objects had been placed somewhere on the mound, at the following stage they had fallen into the moat and became buried under the water-logged ground, and at the last stage they came to be excavated.
H Sakai

Natural durability transfer from sawmill residues of white cypress (Callitris glaucophylla). - Part 2: Laboratory fungal bioassays
2000 - IRG/WP 00-20204
Extracts from sawmill residues of the naturally durable white cypress, Callitris glaucophylla were tested for fungicidal activity in a series of laboratory bioassays. The effects of different extraction solvents, techniques and sources of material on the biocidal efficacy of the resultant extracts were evaluated. Soil jar decay tests were used initially however, contractual time constraints necessitated the development of a more rapid screening technique. A modified sapwood agar media was developed and found to be suitable for testing the extracts. It could be applied to other non-diffusible wood preservatives. Ground white cypress sapwood was impregnated with a range of concentrations of various extracts and gamma irradiated. The treated sterilised sawdust was suspended in water agar. The media were inoculated with a white rot, Lopharia crassa, or a brown rot fungus Polyporus verecundus. Growth of the isolates was monitored for four weeks, enabling dose responses to be accurately determined. Methanol was determined to be the most effective extracting solvent, and toxic threshold values of the methanol extracts were estimated. Fractions of the total extract were also compared. Most fungicidal activity was found in the most abundant fraction, which contained significant proportions of terpenes and other non-polar, low boiling point compounds.
M A Powell, L M Stephens, L Francis, M J Kennedy

Termite and decay resistance of particleboard composed of white cypress pine and radiata pine
1997 - IRG/WP 97-10200
Phenol-formaldehyde bonded particleboard was manufactured from blends of non-durable radiate pine (P. radiate) and heartwood of the naturally durable species, white cypress pine (C. glaucophylla). Board specimens were subjected to bioassays using two termite species, M. darwiniensis and C. acinaciformis, and the basidiomycete fungi, C. puteana and P. ostreatus, and the durability of specimens was compared with that of commercially manufactured particleboard specimens containing either insecticide or fungicide. The aims were to determine whether the natural durability of the boards was modified by the addition of cypress pine and if the durability of boards was comparable to that of boards containing insecticide or fungicide. Particleboard specimens containing cypress pine showed increased durability compared to specimens consisting entirely of radiate pine. There was an inverse relationship between the percentage of cypress pine and mass losses of specimens during the bioassays. During the M. darwiniensis bioassay mass losses of specimens containing 100 or 90% cypress pine heartwood were comparable to those of specimens containing insecticide. However, cypress pine particleboard specimens, irrespective of cypress pine content, were less resistant to attack by C. acinaciformis than specimens containing insecticide. Specimens containing 75% or more of cypress pine possessed similar decay resistance as specimens containing fungicide.
P D Evans, J W Creffield, J S G Conroy, S C Barry

International comparison of three field methods for assessing the in-ground termite resistance of materials - highlights after two years
1999 - IRG/WP 99-20157
First-year results of a comparative study, evaluating the in-ground termite resistance of a range of materials, including CCA and ACQ-treated timbers, using the below-ground exposure, ground contact and graveyard methods against diverse termite faunas were provided in IRG/WP/98-20132. Further annual inspections have confirmed early trends and identified notable differences between sites and methods. Termites have contacted specimens more frequently at tropical sites, irrespective of the method, and in below-ground exposure trials, irrespective of site. Overall, levels of fungal decay have been low. Fungal decay was more prevalent in specimens using the ground-contact and graveyard methods. Notable levels of termite attack have been recorded for some CCA- and ACQ-treated Pinus radiata specimens at the retention of 2kg/m3, after two years or only one year (Phuket, Thailand). Some specimens of the durable timber bald cypress (Taxodium distichum) have sustained significant levels of termite attack and fungal decay.
M Lenz, J W Creffield, A F Preston, B M Kard, C Vongkaluang, Y Sornnuwat

Incising to improve penetration and retention of creosote in small-diameter Kenyan-grown Cypress (Cupressus lusitanica)
2003 - IRG/WP 03-40253
Turning small-diameter plantation thinnings into value-added products has remained a challenge in many countries, including Kenya. The present study reports on a feasible technique to effectively treat small-diameter cypress for use in ground contact. Samples of pole-size Cypress (Cupressus lusitanica), 106 mm and 138 mm in average diameter, were sampled from thinnings in 7 and 12 year-old plantations, 2.0 m posts removed from butt-ends, debarked, air-dried to 15% moisture content, subjected to four patterns of incising and pressure-treated with creosote (60:40 creosote/furnace oil mix) at a commercial treatment plant. Un-incised controls were prepared and treated in the same fashion. All samples were then conditioned for 48 days under cover, leached in running tap water for 20 days, air-dried to 15% MC and final retentions calculated on a weight-gain basis. Discs were removed from the middle portions of the samples and average radial penetration measured. The results indicated that the closer the incisions (20 mm x 20 mm), the higher the average retentions (86.3 and 80.8 Kg/m3) and penetration (16.8 and 13.9 mm) in 7 and 12 year-old posts respectively, acceptable for ground exposure situations. Un-incised controls recorded lower average retentions (38.9 and 37.4 kg/m3) and penetration (6.8 and 5.8 mm), sub-standard for poles and posts for ground contact usage. Incising as a technique to obtain the required retention and penetration for cypress small-diameter fencing posts and utility poles is viable, and should be refined and investigated further, together with an appropriate treatment schedule. An effective treatment technique is necessary to allow utilisation of a substantial volume of small-diameter cypress removed as thinnings and normally considered as waste in this country.
R Venkatasamy

Wood preservation in Kenya
2000 - IRG/WP 00-40190
Focussing an Wood Preservation in Kenya, the Report discusses and elaborates on Education and Training, Research, Wood deteriorating organisms, Treatment Plants and Processes, Preserving Chemicals, Specifications, Markets, Health and Safety and Environmental issues. Education and Research is limited to one Institution only, other Institutions involved with the properties and utilization of wood hardly touches Preservation. Publications and results of Research Projects over the years have emanated from that Institution. Conferences have not been held for a long time in the country. Fungi, insects, including termites, and Marine borers, are all present in the country. The amount of untreated or poorly treated wood lost through the activities of these organisms is substantial. Treatment is usually of a general nature, assuming that Schedules used will protect timber against all agents of decay. The Kenyan Wood Preservation Industry, now 50 years old and with some 27 Plants around the country, has not explored other Wood Preserving Chemicals or Treatment methods. The four Preservatives used are still CCA, Creosote, BFCA and PCP. The Bethel Process is used by all pressure Plants (CCA and Creosote), with only one immersion Plant (BFCA and PCP). Eucalyptus, Acacia,Cypress and some are the species commonly treated, mainly for the local market with some exports. Schedules have not been properly worked out for different end uses. Transmission, Telegraph poles and Fencing posts comprise the bulk of timber treated, with smaller amounts of Construction timber and Horticultural poles. The four Chemicals used are of foreign origin, imported by Treatment Plants. Apart from a few Standards formulated by the Kenya Bureau of Standards (KBS), there are no other Standards or Codes of Practice to guide the Industry and Users of treated timbers. Specifications have not been fully worked out. The KBS is the only Authority responsible for Quality Control and Certification. Health and Safety of Plant operatives is not of major concern. Problems associated with Toxic Preserving Chemicals in the environment has not been fully addressed yet.
R Venkatasamy

MDF manufactured from blends of cypress pine and radiata pine shows enhanced resistance to subterranean termite attack
2001 - IRG/WP 01-40214
Medium density fibreboards consisting of blends of the naturally durable wood species white cypress pine (Callitris glaucophylla) and non-durable wood species were manufactured in a commercial plant and subjected to a bioassay using the subterranean termite species, Coptotermes lacteus. A board composed of 30% cypress pine, 30% slash pine (Pinus elliottii) and 40% of the naturally durable hardwood species spotted gum (Corymbia maculata) was also manufactured and bioassayed against C. lacteus. The aims were to determine (i) whether boards containing cypress pine possessed increased resistance to termite attack compared to a control manufactured entirely from non-durable wood species; (ii) the relationship between the cypress pine content of boards and their resistance (if any) to termite attack; (iii) whether the termite resistance of boards containing cypress pine could be further enhanced by the addition of spotted gum fibre. There was an inverse relationship between the cypress pine content of MDF specimens and mass losses of the specimens during the bioassay, the percentage mass losses of specimens containing 11.4, 16.2 and 34.2% cypress pine being 20.3, 13.4 and 8.8%, respectively, compared to 32.8% for the control, which consisted of non-durable slash pine (80%) and hoop pine (Araucaria cunninghamii) (20%) fibre. There was strong evidence that the inverse relationship between the cypress pine content of boards and mass losses during the bioassay was linear, although a statistically significant quadratic (curvilinear) effect was also apparent. The addition of spotted gum fibre to boards did not increase their resistance to termite attack. Cypress pine heartwood contains a variety of extractives that are either toxic or repellent to termites, and the increased termite resistance of MDF containing cypress pine compared to the control is probably due to the insecticidal effect of such chemicals on C. lacteus. The incorporation of cypress pine fibre into MDF shows promise as an alternative to chemical biocides for increasing the resistance of MDF to termites. However, the response of termites to heartwood extractives varies between species, and therefore further experimentation is needed to test the resistance of MDF containing cypress pine fibre to attack by greater range of wood destroying termites under test conditions that more closely simulate field conditions.
P D Evans, S Dimitriades, C Donnelly, R B Cunningham

Comparison of three methods for assessing the in-ground termite resistance of treated timber, durable timber and plastics at sites in Australia, USA and Thailand - First results
1998 - IRG/WP 98-20132
The in-ground resistance of materials to attack by subterranean termites is most commonly assessed with one form or another of the conventional graveyard method, despite the significant shortcomings of this method. In Australia, an alternative method, in which all samples of test materials are placed below-ground, has been in use for more than 10 years. The method provides reliable exposure of samples to prolonged contact by termites and offers a number of other advantages, notably ease of removal and re-installation of specimens, and protection from fires or damage caused by animals and vandalism. We describe a study in which assessments of materials with the below-ground exposure method were compared with the graveyard procedure and a modification of the South African ground contact method. Sites encompassed a range of climatic conditions and termite faunas, subtropics with species of Reticulitermes in Mississippi, USA; humid tropics with a diverse termite fauna dominated by Macrotermitinae (fungus-culturing termites) in SW Thailand; wet and dry tropics with separate trials for the two economically important species, Mastotermes darwiniensis and the mound-building form of Coptotermes acinaciformis, in Northern Australia; and at a semi-arid inland site with a temperate climate in Eastern Australia where the tree-nesting form of Coptotermes acinaciformis is the dominant species. Materials included in the investigation were: CCA- and ACQ-treated Pinus radiata (each at two retentions), a durable timber (bald cypress, Taxodium distichum) and two plastic cable sheathings (nylon and low density polyethylene). This paper provides details of the trial and gives first observations from inspections at three sites after one year of exposure of the materials to termites.
M Lenz, A F Preston, J W Creffield, K J Archer, B M Kard, C Vongkaluang, Y Sornnuwat

Natural durability transfer from sawmill residues of white cypress (Callitris glaucophylla). - Part 1: Optimisation of the extraction conditions
2000 - IRG/WP 00-30238
As the first phase of a large project aimed at recovering 'waste' durability components from sawmill residues of Callitris glaucophylla, several solvents and extraction methods were evaluated, initially in the laboratory and then at pilot industrial scale. Extracts were compared by crude total dissolved solids content, by chemical analysis using GC-MS and LC-MS, and by laboratory bioassays against termites and decay fungi. Solvent polarity was more important than extraction method: polar solvents extracted greater total amounts, and were comparable to non-polar solvents in extract activity against decay. The latter produced greater specific activity against termites. Drying of sawdust before extraction reduced the yield of some volatile extractive components, but activity was not seriously affected. Extractive components fractionated by column chromatography exhibited a wide range of bioactivities. GC-MS and LC-MS analytical techniques were used to characterise the most active fractions, in which l-citronellic acid and several terpenoids were abundant.
M J Kennedy, Hui Jiang, L M Stephens

Natural durability transfer from sawmill residues of white cypress (Callitris glaucophylla). - Part 4: Analysis of extracts and treated wood for active components
2000 - IRG/WP 00-20215
In order to facilitate the commercial implementation of a large project aimed at recovering 'waste' durability components from sawmill residues of Callitris glaucophylla, it has been essential to develop analytical methodology for the important bioactive components of the heartwood extract. This methodology will be used 1) to standardise the activity of successive production batches, ensuring that batch-to-batch variation is controlled, and 2) to monitor the penetration and retention of active components in extract-treated wood, ensuring that treatment quality is controlled. Analytical techniques used through the project have included both LC/MS and GC/MS, but as most of the extract activity against termites and fungi has now been demonstrated to reside in the lighter fractions, we have concentrated on GC/MS for the routine methodology for both extract activity and wood retention. Penetration is monitored by the application of a chromazurol S spot-test to a freshly cut transverse section. Both cypress heartwood and penetrated sapwood turn red-purple under the conditions of the test, which is not necessarily specific for cypress extractives, but nevertheless useful for routine monitoring of penetration of cypress extracts.
Hui Jiang, M J Kennedy, L M Stephens

Comparing microbial colonisation and Decay Rates of Wood from Sound and Aphid-Killed Kenyan-Grown Mexican Cypress (Cupressus lusitanica)
2006 - IRG/WP 06-10599
Samples of wood from 10, 15, and 30-year old trees attacked and killed by the cypress aphid (Cinara cupressi) and sound Kenyan-grown Cupressus lusitanica trees were investigated for variations in moisture content, density and susceptibility to microbial decay. MC varied with tree age, a normal trend, and between samples from aphid-killed and sound trees. In samples from 10, 15 and 20-year old sound trees, MC was higher by 11.1%, 8.6% and 7.8% respectively, than in samples from aphid-killed trees. Similarly density varied with age, to be expected, and between samples from aphid-killed and sound trees, being 3.5%, 2.6% and 2.1% higher in samples from sound trees of the 3 age classes. Exposure to riverwater and soil revealed a pattern of microbial colonisation and degradation normal for each environment. In riverwater, samples were mainly colonised by bacteria, actinomycetes, stain fungi, and softrot fungi, bacteria and softrot fungi being the main wood degraders, but their action on samples were slow and generally moderate in severity of attack. Exposure to soil followed a similar pattern of colonisation, the principal wood decaying organisms being bacteria and softrot fungi, and to a lesser extent brown and white rot fungi. Samples from both aphid-killed and sound trees were colonised and decayed in a similar fashion, but microbial decay in the soil environment was more pronounced than in riverwater. The soil block test recorded low weight losses after 2 weeks exposure, rising to between 29% and 36% after 12 weeks, with no significant differences between weight losses in samples from aphid-killed and sound trees, or tree age. The results of the study revealed that there are no significant differences between microbial decay susceptibility of wood from aphid-killed and sound trees, and that slight differences in MC and density did not influence decay rate. Consequently, wood from aphid-killed cypress trees should not be considered as of inferior quality, in terms of decay susceptibility, by wood processors and consumers.
R Venkatasamy

Comparative studies on penetration and retention of CCA (C) and creosote in wood from APHID-killed and sound Kenyan-grown Mexican cypress (Cupressus lusitanica)
2006 - IRG/WP 06-40352
Properties of wood from Kenyan-grown Mexican cypress (Cupressus lusitanica), attacked and killed by the cypress aphid (Cinara cupressi), in terms of density and treatability, were investigated in comparison to the properties of wood from sound trees. Density in small wood samples from aphid-killed trees was found lower than density in samples from sound trees, and reduced with tree age in samples from both. However, differences were slight, being 3.8%, 2.5% and 2.3% lower than density in samples of sound trees aged 10, 12 and 14 years respectively. Conversely, penetration and retention of both CCA and creosote were higher in samples from aphid-killed trees of the 3 age classes. Along the grain penetration of CCA was higher by 3.6%, 4.5% and 6.2%, and across the grain penetration higher by 3.8%, 7.0% and 11.3% in samples from aphid-killed trees of the 3 age classes respectively, compared to penetration achieved in samples from sound trees. Higher penetration of creosote in samples from aphid-killed trees was in the order 3.9%, 5.8%, 7.1% along the grain, and 3.7%, 6.2%, 11.9% across the grain. Along the grain retention of CCA in samples from aphid-killed trees was higher by 1.2%, 1.5%, 2.0%, and across the grain higher by 5.1%, 6.3% and 7.4% for the 3 age classes. Similarly, retention of creosote in samples from aphid-killed trees of the 3 age classes was higher by 3.2%, 4.5%, 5.6% along the grain, and 2.6%, 3.2%, 4.6% across the grain. Differences in density and treatability could not be properly explained, but was assumed associated with extensive sap depletion by aphids, interference with tree growth and normal wood formation, hence lowering of wood cell wall materials and increased cellular spaces within the wood cell wall structure of wood from aphid-killed trees. However, the results revealed that differences between wood from aphid-killed and sound C. lusitanica were minimal, and did not warrant wood from aphid-killed trees being branded as of lower quality, and restricted end uses.
R Venkatasamy, F M Opar

Evaluation of natural durability of solid wood and mixed heartwood-sapwood Cypress (Cupressus sempervirens L.) plywood against Basidiomycete fungi
2008 - IRG/WP 08-10645
The aim of this research was to study the response of mixed plywoods composed of durable heartwood and non-durable sapwood to fungal attack. For this purpose, the species of Cupressus sempervirens (cypress) was chosen for its well-known durable heartwood. The evaluation of durability of plywood panels against fungi was done according to ENV 12038 and the fungi used were Coriolus versicolor (CV) and Coniophora puteana (CP). In order to have the basic data on the wooden element of plywood, the natural durability of cypress sapwood and heartwood in the state of solid wood was also determined against fungi according tothe guidelines of EN 350-1. Plywoods made of pure sapwood and pure heartwood (as controls) allowed a comparison with the mixed ones. 17 different plywoods were laboratory made. The influence of thickness of plies, number of MUF glue line, percentage of heartwood plies integrated to sapwood plies in the mixed plywood, and finally, the way of integration of durable plies in to non-durable plies has been evaluated. In case of solid wood, the heartwood of cypress was found “very durable” against both CV and CP while the sapwood was found “slightly durable”. In the case of plywoods, the evaluation of fungal resistance of pure plywood showed a slight diminution in comparison with the solid wood state. This decrease can be explained by a loss of some extractives molecules during the stage of steaming and peeling. In the mixed plywoods, some of the integrations were found more resistant to the fungal attack. These panels were composed of heartwood layers on the surfaces. It was also found that the criteria of vulnerable surfaces or durable surfaces in plywood is more related to its resistance than the criteria of volume of non durable plies or durable plies that is generally recognized
F Faraji, M F Thévenon, N Lemenager, B Thibaut

Utilizing Cypress to improve the decay and termite resistance of OSB panels
2008 - IRG/WP 08-10658
OSB panels were manufactured with mixture of pine and cypress heartwood and lignin and tannin based resins in order to propose an eco-friendly wood composite. The resistance of OSB panels was tested against Reticulitermes santonensis according to the EN 118 and EN 117 standards and field tests methods. OSB made from cypress showed more resistance against the tested termite, the resistance decreased as the percentage of pine increased. The degree of attack differed according the choice of standard procedure. The field test results revealed that in exterior conditions and when the termites had a feeding choice, all mixtures showed the same behaviour.
N Amusant, O Arnould, A Depres, R H Mansouris, T Pizzi, C Baudassé

Termite resistance of pure and mixed heartwood-sapwood Cypress (Cupressus sempervirens L.) plywoods
2009 - IRG/WP 09-10693
The main objective of this research was to evaluate the ability of different plywoods made of durable heartwood and/or non-durable sapwood to resist termite damage. The well-known durable cypress (Cupressus sempervirens) was chosen for this study. The natural durability of cypress solid wood, divided into sapwood and heartwood, as well as the durability of 17 different laboratory manufactured plywoods, was evaluated towards Reticulitermes santonensis termites. The durability towards termites is discussed by taking into account the influence of composition of the panel (proportion of durable/non durable timber), the ply numbers, the ply thickness, the number of glue lines, and the way of integration of the different plies.
F Faraji, M-F Thévenon, B Thibaut

Wart Morphology can Distinguish White Cypress Pine from the Less Durable Species, Black Cypress Pine
2009 - IRG/WP 09-20406
White cypress pine (Callitris glaucophylla) wood is durable enough to be used outdoors, but occasionally there are reports of its premature failure in ground contact, which may be due to its substitution by the less durable species, black cypress pine (C. endlicheri). It has been difficult to prove this, however, because the woods of both species are very similar in structure and cannot be separated using conventional anatomical features. This study examined whether differences in the size and morphology of warts on tracheid walls in the two species could be used to identify them. There were significant differences in the height, width and shape of warts in the two species, but there was considerable overlap in the distribution of these parameters between specimens. Warts in C. endlicheri were more likely to be bent-over near their tops than those in C. glaucophylla, and the angle bending of warts was greater in C. endlicheri. Quantification of these parameters produced complete separation of multiple specimens of the two species, and could potentially be used to help determine whether premature failure of C. glaucophylla heartwood in ground contact is the result of its substitution by C. endlicheri.
R Heady, R Cunningham, P Evans