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The high decay resistance in the sapwood of the naturally durable Malaysian hardwood Belian (Eusideroxylon zwageri)
2001 - IRG/WP 01-10410
It has long been assumed that the observed natural durability of the heartwood in certain timbers is perhaps associated with a relatively lower decay susceptibility also of the sapwood of these species. While the heartwood of Belian is reputedly highly decay resistant among the tropical hardwoods of Southeast Asia, laboratory decay tests reported in this paper have also confirmed the high decay resistance of the sapwood of this timber species. The sapwood of Belian is found to be resistant to decay by soft rot (Chaetomium globosum), white rot (Pycnoporus sanguineus & Coriolus versicolor) and brown rot (Poria sp. & Gloeophyllum trabeum) fungi after 12 weeks of decay testing, sustaining <2% mass loss, equivalent to that in its heartwood. The reference sapwood species Rubberwood (Hevea brasiliensis) and the heartwood of Kempas (Koompassia malaccensis) sustained significant mass losses from decay of up to 59% and 17%, respectively. Microscopic observations of Belian sapwood revealed extensive proliferation of extractives in the lumina of various cell types showing a pattern of extractive distribution similar extent to that in the heartwood tissues, although the extent of cell filling by extractives was not quite as high as for the heartwood. It is plausible that the inherent wood extractives deposited in the cells confer the same degree of anti-fungal properties to both the heartwood and sapwood of Belian.
A A H Wong, A P Singh

Evaluation of the natural durability and ultrasonic method for decay detection of some european hardwood and softwood species
2004 - IRG/WP 04-10537
This paper presents the first part of an investigation on the natural durability of mixed plywood made of durable and non durable plies from the following selected timbers : Cedrus atlantica, Cupressus sempervirens, Castanea sativa, Populus sp. I 214 and Fagus sylvatica. In order to carry out this study, the natural durability of the massive wood used to manufacture the plywood panels was assessed towards wood both white and brown rots (Coriolus versicolor and Coniophora puteana respectively) according to the guidance of the EN 350-1 standard. The sampling was done by taking into account the axial and radial position of the wood samples (sapwood, inner heartwood, outer heartwood) into the log, and sapwood was separated from heartwood when possible. Moreover, the ultrasound velocity was evaluated on these wood samples before and after fungal degradation. On the other hand, the density and the longitudinal modulus of elasticity of the timbers used were measured. In terms of natural durability, the results obtained showed that some differences were noticed between the sapwoods tested, but all of them were considered as non durable. Poplar and beech were shown non durable, on the contrary of chestnut, cypress and cedar heartwood that were very durable. A significant decrease of ultrasound velocity was shown when the decay and the mass loss were considerable. It appeared also the response of the ultrasound velocity was different from brown and white rot decay. Nevertheless, ultrasound velocity measurement was an efficient non-destructive method to evaluate biological decay. The natural durability, as well as the physical and mechanical properties evaluated on massive wood are of interest in order to predict the properties of the plywood that will be manufactured from these studied timbers. These results could be helpful to determine the influence of percentage and pattern of the different plies within the plywood panel, ply thickness and glue lines on the natural durability of plywood.
F Faraji, M-F Thévenon, B Thibaut

Prevention of non-microbial sapwood discolorations in hardwood lumber: chemical and mechanical treatments
1997 - IRG/WP 97-30137
Sapwood discolorations in hardwood lumber that are non-microbial in origin result from the formation of pigmented starch-like granules in ray parenchyma cells. These discolorations can be prevented by treating unseasoned lumber with an antioxidant (sodium bisulfite). Exposing unseasoned lumber to microwaves or treating logs with fumigants also will prevent these discolorations. Subjecting unseasoned lumber to mechanical stresses (compression and/or vibration) also prevents sapwood discolorations of non-microbial origin. A machine to mechanically stress lumber and thereby prevent these discolorations has been built and is being field-tested at cooperating sawmills.
T L Amburgey, S Kitchens

Lyctine susceptibility testing and dealing with rarely susceptible hardwood species
2007 - IRG/WP 07-10607
This study examined the lyctine susceptibility of 16 timber species or hybrids. Several of the timbers have been placed previously in a ‘rarely susceptible’ category, but for standards and compliance purposes, such in-between ratings are not acceptable. Timber specimens were spot tested for starch content, and exposed to three species of lyctine beetles in an insectary. New criteria were developed to divide the problematic ‘rarely susceptible’ species, including naming a species non-susceptible if significant attack was limited to 6 mm depth, as this region is routinely lost upon sawing. Lyctine susceptible species were Erythrophleum chlorostachys, Eucalyptus delegatensis grown in Tasmania but not Victoria or NSW, Eu. regnans/obliqua hybrid, Corymbia nesophila, Eu. fibrosa, Eu. grandis, Eu. crebra, Eu. argophloia, Eu. dunnii, Eu. regnans from Tasmania, Eu. saligna, and Eu. grandis/saligna hybrid as both parent species were susceptible. The non-lyctine susceptible species were Eu. cloeziana, Eu. pilularis, Eu. sieberi, and Eu. tetradonta. Starch could be detected using the spot test in 126 of the 129 specimens rating S2 (moderate) or S3 (heavy) for lyctine attack. However, many specimens with starch were not attacked, for reasons unknown but unlikely to include narrowness of pores, for the timber species examined.
L J Cookson, J Carr, N Chew, J W Creffield

Field performance of wood preservative systems in secondary timber species
1997 - IRG/WP 97-30152
The objective of this ongoing study is to evaluate the performance of new, potential, and standard wood preservative systems in secondary North American timber species. Eleven preservative systems were evaluated in this study - ACQ Type B, Copper Citrate 2: l, CDDC, chlorothalonil/chlorpyrifos, copper-8-quinolinolate, tebuconazole/chlorpyrifos, RH287, propiconazole/chlorpyrifos, copper naphthenate, CCA. and creosote. Field evaluations are being performed with ground contact field stakes and termite-specific testing in Hawaii, along with laboratory soil bed tests. The major wood species used with all the systems and evaluation methodologies are loblolly pine, northern red oak, tulip poplar, and cottonwood. More limited evaluations (field stakes only) are being conducted with eastern hemlock, red maple, and sweetgum. Information is presented from laboratory soil bed, field termite, and field stake evaluations. There is good correspondence between soil bed and field stake results. The more highly developed preservative systems and those in an AWPA P9 Type A oil carrier tend to perform better, and there can be a strong affect on performance from the wood species.
P E Laks, K W Gutting, R C De Groot

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

Effectiveness of "Gang-Nail" plates in preventing splitting of Eucalyptus poles and Brazilian hardwood sleepers
1984 - IRG/WP 3262
This paper presents the results of some tests carried out with an anti-splitting device, placed on the end surfaces of Eucalyptus spp utility poles and Brazilian hardwood sleepers at the beginning of an air-drying period. The type of device used, a "Gang-Nail" plate, reduces significantly the splits at the end-surface of poles, but reduces only a little the splits occurring in sleepers.
A M F Oliveira, J A C Sodré, O B Neto

Soil virulence tests using Scots pine sapwood
1973 - IRG/WP 222
Following the tests reported in Document No: IRG/WP/210, in which soils from different laboratories were investigated for virulence, supplementary tests have been carried out using Scots pine sapwood and an extended incubation period.
J K Carey, J G Savory

Progress towards controlling soft rot of treated hardwood poles in Australia
1977 - IRG/WP 289
H Greaves

Essais biologiques sur poteaux traités à la Wolmanit C.B. suivant le procédé Boucherie modifé
1974 - IRG/WP 336
D Lapetite, C Jacquiot, J Campredon

An investigation of the effects of pre-steaming on the treatment of sawn spruce timber with Celcure A, a copper-chrome-arsenic preservative
1981 - IRG/WP 3150
Difficulties in the treatment of spruce using standard vacuum/pressure techniques with both water-borne and organic solvent preservatives are well known. We have evaluated the influence of steaming on treatability with a waterborne CCA preservative.
C R Coggins

Resistance to soft rot of hardwood plywood treated with CCA salt
1983 - IRG/WP 3258
Plywood made from indigenous hardwoods was treated at an average loading of 34 kg Celcure A per m³ and was installed in a field test. After 20 years the samples were only slightly attacked by soft rot and the glue bonds were still intact.
R S Johnstone

Possibility of use of wood species per class of biological risks. Attempt to determine criteria based on Pr EN 350-1/2/3
1992 - IRG/WP 92-2409
M Rayzal

The effect of sapwood on the rate of deterioration of fence posts
1986 - IRG/WP 1277
In order to evaluate the effect of the presence of sapwood on the rate of deterioration of fence posts, 30 specimens with and without sapwood of Eucalyptus citriodora, Eucalyptus paniculata, Eucalyptus saligna and Eucalyptus tereticornis were exposed in three test sites in the State of São Paulo, Brazil. The results of the inspection carried out in 1985, after 5 years of exposure, are reported in the present paper.
M S Cavalcante, G A C Lopez, E S F Mucci, R G Montagna

Rational weight per weight (w/w) qualifying retention from a pole bank in Bangladesh
2000 - IRG/WP 00-40187
Weight per weight (w/w) vs weight per volume (w/v) retention study revealed that the w/w % retention is found to be appropriate and uniform for all timber species in respect of its real effectiveness. The pole species having density below 512 kg/m3 (32pcf.) showing w/v retention below 20kg/m3 (1.25pcf.) have equal w/w retention of 4%. The apparently reduced w/v retention of low density poles will be compensated/adjusted by total additional preservative required for higher dimension of poles compared to standard US origin southem pine poles (Pinus elliotti, P. echinata, P. taeda, P. palustris) required to satisfy desired bending load. The pole species having density higher than 512 kg/m3 (32 pcf.) will also give real equal w/w retention of 4% by showing higher w/v retention. About double w/v retention will be required for Bangladesh orgin sundri (Heritiera fomes) or equivalent pole species which is very essential for higher service life compared to softwood poles. In softwoods cell wall can be completely penetrated with CCA to protect soft rot fungi but such function in dense hardwoods may be carried out by additional retention. Remedial treatment is found to be the vital issue for hardwood pole for long term satisfactory use in contact with ground even with possible higher retention of w/w 4% or above. Dual treatment (CCA-C + creosote) is another solution for adequate service life of hardwood poles.
A K Lahiry

Efficacy of some extractives from Pinus heartwood for protection of Pinus radiata sapwood against biodeterioration. Part 1: Fungal decay
1995 - IRG/WP 95-30072
Chemical compounds thought to contribute to the natural durability of heartwood of Pinus spp. were either chemically synthesised in the laboratory or extracted from the heartwood of Pinus elliottii or Pinus caribaea. These compounds included the stilbenes, pinosylvin and its mono- and di-methyl ethers, and the flavonoids, pinobanksin and pinocembrin. Small blocks of Pinus radiata sapwood were impregnated with methanolic solutions of pure compounds or heartwood extracts, to a range of retentions extending above and below the concentration of each compound known to occur in the heartwood of Pinus spp.. Fungicidal efficacy of these compounds has been evaluated by exposure of treated blocks to pure cultures of a white and a brown rot, in addition to an unsterile soil test.
M J Kennedy, J A Drysdale, J Brown

Analysing the characteristic role of moisture content for drying and fluid flow in Sitka spruce. - Part 1: The drying process of sapwood and heartwood of two different thickness of Sitka spruce using a kiln. - Part 2: Effects of moisture content on longitudinal permeability of Sitka spruce in vertical variation of the tree
2000 - IRG/WP 00-40173
The characteristic role of the moisture content in Sitka spruce (Picea sitchensis (Bong.) Carr.) that grown in the United Kingdom was examined by this study on the basis of (1) the reduction of moisture content in two different thickness of sapwood and heartwood by kiln drying process, and (2) the effects of moisture content to the longitudinal void volume filled of tanalith-C by the full-cell process from base (1 m) to apex (3 m) of the tree in sapwood zone. Accordingly, conclusions on indication of the drying process of sapwood and heartwood, and vertical variation of longitudinal flow with effects of moisture were listed separately: (1) Comparison of Drying Characteristic of Sapwood and Heartwood: The two different thickness (300x30x30 mm3 and 300x20x20 mm3) of sapwood and heartwood of Sitka spruce was dried using the suggested drying schedule in kiln. The reduction of moisture was schematically diagrammed according to sapwood and heartwood stakes. The reduction of moisture followed the same downward trend that sapwood (S) loses more moisture than heartwood (H) although the small stakes of S and H lost moisture rapidly compared with the large ones. (2) Vertical Variation of Moisture Content and Longitudinal Permeability: The 90 kiln dried defect free sapwood stakes (150x25x25 mm3) of Sitka spruce was taken from base to apex of the trees at 1, 2 and 3 m above ground level. After having the determination of moisture content in each experimental stake, the treatment was carried out by the full-cell process with CCA preservative (Tanalith-C) using a model pressure treatment plant. Significant differences observed among the tree heights from 1 to 3 m showing that slightly increases of moisture content from base to apex and conversely decreases of longitudinal void volume filled by preservative fluid.
I Usta

Results of field tests on the natural durability of timber (1932-1975)
1976 - IRG/WP 3105
This paper describes a continuing field stake trial to determine the natural resistance of different species of timber to decay. Data are presented for about 180 timbers, covering over 6000 stakes, and the results are discussed in terms of a natural durability classification.
D W Purslow

The formation of organotin carboxylates in bis(tributyltin) oxide - treated Pinus sylvestris sapwood
1990 - IRG/WP 3618
Tributyltin compounds have been successfully used for many years as wood preservatives, although their chemical nature in timber have not been fully elucidated. This study by 119Sn and 13C NMR spectroscopy has shown that, on impregnation into Pinus sylvestris sapwood, bis(tributyltin) oxide, (Bu3Sn)2O, is rapidly converted to tributyltin carboxylates, Bu3SnOCO·R, via reaction with components of the wood resin. It is further suggested that the formation of these species is a prerequisite for the known disproportionation reaction which occurs in (Bu3Sn)2O - treated timber.
S J Blunden, R Hill

Susceptibility of angiosperm sapwood to white-rot fungal colonization and subsequent degradation: a hypothesis
1997 - IRG/WP 97-10211
It has long been recognized that angiosperm sapwood in nature is relatively easily and preferentially degraded by white-rot fungi. This susceptibility to white-rot fungi is generally believed to be mainly caused by the structure and concentration of angiosperm lignin. However, an explicit explanation as to why lignin structure makes a particular wood vulnerable to white-rot colonisation and subsequent degradation has apparently never been given. We propose that free phenolic groups in wood, such as those present in the lignin or heartwood extractives, can act as free radical scavengers (antioxidants) which disrupt the various white-rot free radical degradative mechanisms. Consequently the presence of a relatively high free phenolic "density", such as that present in gymnosperm sapwood or angiosperm heartwood, may inhibit white-rot degradation. Conversely, white-rot fungi may find wood with a relatively low free phenolic content, such as angiosperm sapwood, easy to colonize. The complex structure of angiosperm wood, in which different cell types have different amounts and types of lignin -- and consequently different levels of free phenolic "densities" -- influences the susceptibility of angiosperm wood to initial white-rot colonisation and, perhaps, also the subsequent decay rate. In addition to the free phenolic ``density" other factors, some as yet unknown, undoubtedly also affect the decay resistance of a particular wood.
T Schultz, D D Nicholas

Tests on preservation of wood against marine borers
1976 - IRG/WP 417
The Instituto del Legno has carried out for some years a series of trials about the biodeterioration of wood in the sea. The investigations included the settlement and activity of marine borers, the natural durability of indigenous and tropical woods and the preservation of wood for marine use. This paper reports the trials on the effectiveness of some preservatives in protecting wood against marine borer attack. The trials were carried out at Follonica station, where some investigations had shown that untreated pine samples submerged in the sea were totally destroyed by marine borers within 1 year. Follonica station, latitude 42° 55&apos; North and longitude 10° 45&apos; East, is situated on the Tyrrhenian sea. The recorded temperature varies between 12°C (January to March) to 25°C (July to September), salinity between 37 to 38% and pH about 8. The borers observed in wood were: Nototeredo norvagica Spengler, Bankia carinata Gray, Limnoria tripunctata Menzies and Chelura terebrans Philippi.
A Gambetta, E Orlandi

Adequate preservative treatment of tropical and subtropical hardwoods for electric anchor logs
1997 - IRG/WP 97-40101
Most available 27 different hardwood species grown in Bangladesh was investigated regarding suitability as CCA-C (chromated copper arsenate type-C) impregnated anchor logs for rural electrification programme. The kiln-drying properties, sapwood thicknesses, CCA treatability grades of sapwood and heartwood, natural durability of heartwood and CCA retainability at specific assay zone separated 27 hardwoods into two different treatment groups A and B. The logs of both the groups were full cell pressure treated at initial vacuum of 600-700 mm Hg and at impregnation pressure of 14-18 kg/cm2. The logs are equivalent regarding service life. The treatment group A includes 7 species, characterized by pretreatment moisture content of 15%, thin sapwood thickness of at least 25 mm, high natural durability and refractory to treatment of heartwood, penetration requirement of at least 25 mm plus 100% sapwood with treatment grades of 75% (+++) and retention requirement of 20 kg/m3 dry oxides in an assay zone of 5-25 mm. The treatment group B includes 20 species, characterized by pretreatment moisture content of 20% thicknesses of sapwood and treatable wood equivalent to at least 44% of radius of logs, low natural durability of heartwood, penetration requirement of at least equivalent to 44% of radius of logs plus 100% sapwood with treatment grades of 75% to 100% (+++ to ++++) and retention requirement of 20 kg/m3 dry oxides in an assay zone of 12-50 mm.
A K Lahiry

Effect of Trichoderma harzianum on induction of laccase by Trametes versicolor on ponderosa pine sapwood
1996 - IRG/WP 96-10177
Trichoderma harzianum has long been studied as a possible biocontrol agent against wood degrading fungi, and has provided varying degrees of protection in several European field trials. In laboratory trials, however, this fungus appears to be less active against white rot fungi. This characteristic was studied using a wood wafer sandwich procedure which simultaneously expose ponderosa pine sapwood wafers with and without exogenous nutrients, to both the biocontrol agent and Trametes versicolor. The results indicated that the biocontrol agent limited but did not completely inhibit weight loss by the decay fungus. Extracts of fungal exposed wafers indicated that the bioprotectant appeared to stimulate laccase production by the white rot fungus. Laccase production is normally associated with secondary metabolism induced by depletion of one or more nutrients in the substrate. The biocontrol agent apparently stimulated this process, thereby potentially accelerating the decay process. The implications of these results with regard to long term biocontrol performance are discussed.
E A Canessa, J J Morrell

Inspection of tropical hardwood window frames in Nigeria for decay presence
1987 - IRG/WP 2294
A method of in situ inspection of hardwood window frames for expression of decay is discussed in this paper. The results show that about 6% of the frames inspected or 23% of the volume of wood in all the frames sampled in buildings erected between 1920 and 1984, exhibited evidence of advanced decay. Protection by the length of the eaves, species of the framing timber used, length of exposure to service, type of housing estate and direction which frames faced, all appeared not to significantly affect the initiation and progression of decay of hardwood window frames of buildings sampled in this work. The trend of results however showed that windows sampled in Government Reservations and private low density layouts, exhibited decay proportions of 13-15% which were below those in private high density layouts and public Institutions (23-24%). Windows facing North and South had relatively higher decay proportions (21-27%) than windows facing East and West (17-18%).
M A Odeyinde, M A Amakiri, E B Lucas, J O Eyenike, S Akanni

Resistance of painted pine sapwood to mould fungi. Part 1. The effect of waterborne paints and fungicides on mould growth
1997 - IRG/WP 97-10233
The efficacy of different fungicides in acrylate and alkyd paints to protect pine sapwood against mould fungi was studied. The acrylate and alkyd paint systems with and without a preservative dipping treatment prior to painting were also used. Differences in the efficacy of the fungicides to protect the paint film were found. The paint films with isothiazolon and IBPC were resistant against mould fungi but the paint films with propiconazole were susceptible to mould. The mixture of propiconazole and IPBC or propiconazole and isothiazolon performed well even at a low concentration. The dipping treatment alone and some fungicides in the paint films supported even higher mould growth than was observed on untreated wood. The most effective combinations were free from mould growth after 26 weeks at RH 100%. In future, the effect of 26 weeks&apos; natural weathering on mould growth will be assessed and the results of the mould test and natural weathering will be compared. The study is a part of a project CT94-2463 in the AIR programme of DG XII.
H Viitanen, P Ahola

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