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Color change of timber exposed outdoors - Influence of season exposure test starts
2019 - IRG/WP 19-40865
For the client the material and color of the exterior wall are important, because they affect the impression of the building [1]. However, discoloration of the exterior wall begins as soon as the building is completed, by various factors such as rainfall. We tried to quantitatively evaluate the changes of the exterior wood, and to organize the influences of climate conditions, in order to use the discoloration as design factor. It seems that the difference in the color changes in an exterior wood surface is remarkably influenced by what season the test begins. In order to confirm the difference in the color changes, the starting test month was shifted by one month for each specimen. Those plates were scanned at some intervals to get image data and the chromaticity was measured with a colorimeter. As a result, the following was clarified. The color change was divided into the following two patterns. A: Red → yellow → white → black, B: Red → yellow → black. Black discoloration occurred due to the plate material reaching severe climatic conditions after the ΔL * value reached the maximum value. Lignin is eluted from wood with rain and decolored with ultraviolet rays to turn white [2]. However, it seems that the plate material becomes black as soon as it reaches high-temperature and humidity (without passing through the white period). We believe that the white period is the period until it is hit by hard climate conditions. When mild conditions continue, the white period is extended. Initial discoloration is slow under mild conditions.
K Usami, H Ishiyama

Wood preservation in the USA
1982 - IRG/WP 3215
This report is a comprehensive survey of the status of the wood preservation field in the U.S.A. at the start of the 1980s. The importance of wood preservation is discussed and its industry described. Various statistics and analyses regarding the use of treated wood have been compiled. Both pressure and non-pressure applications have been covered, as well as remedial treatments and pest control operations. A list of American organizations concerned with wood preservation have been included, together with the various research laboratories which are studying the biodeterioration of wood and its protection. Information is given on the standards and specifications which are in current use. The report, which is fully referenced, ends by suggesting possible future trends for wood preservation in the U.S.A.
D D Nicholas, R Cockcroft

Laboratory culturing and decay testing with Physisporinus vitreus and Donkioporia expansa orginating from identical cooling tower environments show major differences
1996 - IRG/WP 96-10184
Both Basidiomycete fungi Physisporinus vitreus (Pers.:Fr.) P. Karst. and Donkioporia expansa (Desm.) Kotl. & Pouz. were isolated from identical cooling tower environments. Azobé heartwood (Lophira alata), a very durable tropical wood species was totally deteriorated in cooling towers in a similar way by both fungi. First attempts to culture Physisporinus vitreus in laboratory circumstances showed a need for climatic conditions with higher temperatures and higher relative humidity compared to standard conditions known for most Basidiomycete fungi. Moreover there is a supplementary need to alter the acidity of the malt-agar medium and to add a protein nitrogen source like pepton. Identical culturing conditions were supposed for the Donkioporia expansa isolate. However the alteration in acidity is not beneficial for the growth of this cooling tower fungus. High mass loss figures up to 50% were recorded for non-durable wood species inducing wood moisture contents of over 150%, but only a slight growth stimulation on azobé could be observed under laboratory conditions.
J Van Acker, M Stevens

Utility, deterioration and preservation of marine timbers in India
2005 - IRG/WP 05-40314
Timber is extensively used in India in the marine environment for various purposes due to its several advantages over modern materials. Infact, its use is increasing in recent years, finding wider and wider applications and this scenario is not going to change in the near future. Though, the bio-deterioration problem is found very severe in tropical waters, still indigenous methods are widely employed for the protection of fishing craft and the present level of chemical treatment is well below 5% of total timber used. This is due to socio economic problems of the potential timber user groups, unavailability of treatment plants in the coastal areas, lack of awareness in user groups, etc. In this paper, types of fishing craft used in the country, timber uses in the marine environment, bio-deterioration losses, research conducted on bio-deterioration aspects at various places and methods applied for the protection of wooden structures are presented.
B Tarakanadha, M V Rao, M Balaji, P K Aggarwal, K S Rao

Soft rot and bacterial decay in preservative treated eucalypt power transmission poles
1982 - IRG/WP 1155
Bacterial type decay was observed in CCA and PCP treated eucalypt power transmission poles. Detailed observations made with the SEM revealed bacterial colonisation and decay, especially in fibres. Plug samples taken from poles throughout Queensland were examined for preservative retention and presence of soft-rot decay. The severity of decay was different according to location, retention and species.
L E Leightley

Examination of timbers from the Mary Rose in storage
1988 - IRG/WP 4149
Timbers from the Tudor ship, Mary Rose, have been examined for the presence of fungal fruiting structures. Wood specimens were also examined for the presence of microbial decay patterns using light and scanning electron microscopy. Structural timbers were surveyed using the Pilodyn for an overall picture of the extent of decay. Mary Rose timbers were predominantly inhabited by marine fungi. Fourteen species were found fruiting on the surface but fungal decay was localized. Bacterial erosion and tunnelling of the wood cell wall were observed, but were rare. The Pilodyn has shown that decay in timbers exists in isolated pockets. The storage site has proved to be efficient in minimizing further microbial decay, while maintaining the waterlogged state of timbers.
R Mouzouras

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

Use of the Pilodyn to assess deterioration of treated aspen waferboard after 30 months of outdoor exposure
1986 - IRG/WP 2254
Samples of preservative treated aspen waferboard exposed outdoors for 30 mo. were compared using pin penetrations of the 6 Joule Pilodyn. These results correlated well with rankings of treatment performance based on more laborious standard mechanical tests, and demonstrate the potential for use of the Pilodyn as a tool to evaluate wood composites in test exposures with minimal destruction.
E L Schmidt, M G Dietz

The influence of age on retention and fixation of CCA in pressure-treated Kenyan-grown Eycalyptus saligna: Summary of findings
2002 - IRG/WP 02-30296
The present study investigates the influence of age on retention and fixation of copper-chrome-arsenate (CCA) in Kenyan-grown Eucalyptus saligna. Samples for the study were obtained from sound trees aged 4, 8, 12, 16, 20 and 24 years. Test samples were radially cut from round material to represent total sapwood and heartwood for each age class, and measured 50mm in thickness, 100mm long, with widths varying according to the radii of the pieces. The samples were air-dried to an average of 15% moisture content, end-sealed, and treated at a commercial pressure treatment plant with 6% CCA-C (oxide type). They were subsequently conditioned for 6 weeks, air-dried to 15% MC, leached in running tap water for 9 days, re-dried to 15% MC, retentions calculated and results analysed. The results indicated a decreasing trend in retention with increasing age, but substantially higher fixation of the preservative was achieved in samples from older than younger trees. Samples from 4-year old trees with wider sapwood bands achieved consistently higher initial retentions (31.4Kg/M3) compared to those from 24-year old trees with narrower sapwood bands (9.4Kg/M3). However, losses through leaching were higher in samples from younger trees, 14.5Kg/M3 (46.2%) in 4-year old trees, compared to 0.8Kg/M3 (8.5%) in 24-year trees. It was also noted that both retention (31.4 -28.6Kg/M3), and percentage losses of CCA through leaching (46.2-41.6%), were higher in samples from trees between 4 and 8 years, but markedly decreased in samples from trees of between 20 and 24 years, 12.8-9.4Kg/M3 and 10.2-8.5% respectively. Fixation of CCA proved to be low in samples from younger trees, 53.8% and 58.4% for 4 and 8-year old trees respectively, but substantially higher, 89.8% and 91.5%, in samples from 20 and 24-year old trees. Treated eucalyptus poles and posts in the country are invariably from younger trees, and the recommended CCA ground contact retention of 18.0Kg/M3 for pressure treatment may not be adequate.
R Venkatasamy

Importance of bacteria in the deterioration of archaeological woods
1995 - IRG/WP 95-10122
An electron microscopic study of archaeological woods from different sites and of different ages revealed that the woods had been attacked by erosion bacteria, tunnelling bacteria and soft rot fungi. Bacterial erosion appeared to be most widespread, and was present independently as well as together with tunnelling and soft rot attacks. Thus, in many instances bacterial erosion was the only type of microbial attack present. This work recognizes the important role bacteria play generally, and erosion bacteria particularly, in the deterioration of waterlogged archaeological woods.
Yoon Soo Kim, A P Singh, T Nilsson

Ultrastructural aspects of bacterial attacks on an archaeological wood
1993 - IRG/WP 93-10007
Transmission electron microscopy of wood from a Chinese ship submerged in the mud for over 900 years showed bacteria to be the main factor for its deterioration. The micromorphology of degraded wood cell walls was similar to that observed during the attacks of wood by erosion bacteria. Other bacterial forms, previously considered lo be scavenging bacteria, were also abundant in degraded areas of the wall. The observations on the breakdown of the waterlogged archaeological wood are discussed in context with the available information on bacterial degradation of wood under near-anaerobic conditions.
Yoon Soo Kim, A P Singh

Highly virulent wood-rotting Basidiomycetes in cooling tower timbers
1995 - IRG/WP 95-10125
Over the past ten years most industrial cooling towers changed their water treatment systems in order to meet environmental requirements. Since this alterations wood rot attack has been reported more frequently. Several Basidiomycete fungi were isolated and determined. Amongst the most important ones are strains of Physisporinus vitreus (Pers.:Fr.) P. Karst., Phellinus contiguus (Fr.) Pat. and Donkioporia expansa (Desm.) Kotl. & Pouz.. In situ total deterioration has been reported of highly durable wood species like azobe (Lophira alata), bangkirai (Shorea leavis) and Californian redwood (Seqouia sempervirens) and of CCA-treated softwood, e.g. Douglas fir. The Donkioporia strain was only recently isolated while on lab-scale research is ongoing to stimulate the growth of Phellinus. The growth under laboratory conditions is not evident for these fungi and different parameters affecting growth were investigated. After altering the malt-agar as medium and improving climatic conditions fungal growth of Physisporinus in laboratory conditions on durable wood has been succesful already. Some preliminary results related to the changes in water treatment are discussed.
J Van Acker, M Stevens, V Rijckaert

Effects of terpene compounds on the growth and peroxidase activity of Phellinus pini
1979 - IRG/WP 2130
The volatile compounds myrcene, limonene, a-pinene, a-terpineol, D-fenchol and 1,8-cineole, present in the oleoresin fraction of coniferous wood, were tested individually and as mixtures for their effect on the growth and peroxidase activity of cultures of six strains of Phellinus pini (Fr.) A.Ames and one strain of Phellinus chrysoloma (Fr.) Donk (Phellinus pini var. abietis (Karst.) Pilát). Phellinus pini was more tolerant of the substances than Phellinus chrysoloma. There were differences in the tolerance and peroxidase activity between the strains of Phellinus pini. Peroxidase activity was generally higher in the test cultures than in the controls, but was lower in cultures exposed to 1,8-cineole and a-terpineol.
L Väisälä

An evaluation on durability of untreated mining timber support
1997 - IRG/WP 97-20121
Wedge blocks in dimension of 5 x 7 to 8 x 155 cm3 were cut from indigeneous scots pine pitprops. Each of wedge block pairs were numbered and half of them were placed as the test blocks between the steel arches and the strata in a hard coal pit. Controls in laboratory and test wedge blocks in the mine were then sawn into 20 by 20 by 300 mm standard test sticks. Impact bending, static bending and MOE and specific gravity were determined to evaluate the natural durability of timber support against biodeterioration on the test sticks. Strength and specific gravity losses were calculated as a percentage of control values. Furthermore, relationships between residual strength values and losses in specific gravity were statistically evaluated. At the end of exposure period of 2.5 months, decreases in impact bending strength of scots pine wedge blocks were found 46.19%, in static bending strength 28.21% and in MOE 19.54% while the loss of 4.36% in specific gravity was determined. Blue staining moulding and brown-rot were identified on the wedge blocks.
A Bobat

The evaluation of the occurrence of soft rot in creosoted wooden poles
1988 - IRG/WP 1368
The occurrence of soft rot decay in creosoted wooden poles for overhead power lines was investigated by collection of field samples, their subsequent microscopic examination and statistical analysis of the data collected. Examination of samples collected from 296 poles revealed that approximately 15% of the pole population studied (Eastern Electricity Board) showed the presence of soft rot decay. Further, it was found that of undated poles, (those emplaced before 1953,) 17% displayed soft rot attack.
A Wylde, D J Dickinson

Effect of vegetable compost on leaching of CCA components from treated wood - An Update
1995 - IRG/WP 95-50048
In an earlier study, the effect of compost on CCA-C leaching was compared with leaching losses under different exposure conditions. Small treated cubes (25 mm³) were destructively sampled over a 12 month period and the residual CCA determined for exposure to compost in a compost bin, exposed to natural rain and buried in soil. This study provides a comparison after 3 years of samples exposed to compost and to natural weathering and summarizes CCA leaching losses from a treated wood compost bin after 12 months use. On the basis of small treated cubes (25 mm³) significant losses of all CCA components has occurred after 3 years exposure to compost. Copper has the most significant losses. After three years, blocks exposed to compost were extensively degraded by soft rot and other fungi, probably as a result of the high copper losses. The losses from the actual compost bin are highly variable and not statistically significant. As observed with the blocks, copper was preferentially extracted. There was an increased level of all contaminants in the compost, mainly concentrated in the 0-25 mm zone adjacent to the treated wood panels. Considering the increased rate of depletion of CCA components and the more rapid biological degradation of wood exposed to compost, we do not recommend the use of CCA treated wood for this purpose.
P A Cooper, Y T Ung

Microbial decay of an archaeological wood
1994 - IRG/WP 94-10053
A light and transmission electron microscopic investigation of an archaeological wood was undertaken to determine the cause of its deterioration. The wood came from a bulwark constructed in early 1100 in the lake Tingstäde Träsk on the island Gotland in Sweden. The samples of the wood, which was identified as Pinus sylvestris, were taken from a depth of 0.85 m below the bottom level. The wood was found to be heavily deteriorated, and from the micromorphology of decay observed under light and transmission electron microscopes it was concluded that the wood had been largely attacked by erosion bacteria. The degradation of wood components was quite variable, some cell structures/types showing greater resistance than others. The S2 wall layer of axial tracheids, which formed the bulk of the wood, was degraded most. In comparison, ray tracheids appeared completely resistant. Other cell structures/types, such as pit borders of axial tracheids and ray parenchyma cells, displayed features that were intermediate between the extremes noted above. These features are discussed in the light of available information on bacterial erosion of wood cell walls and on chemical composition of these cell structures/types in pine wood.
A P Singh, T Nilsson, G F Daniel

A survey of the incidence of decay in copper-chrome-arsenate treated trellis support posts used in horticulture in New Zealand
1984 - IRG/WP 1225
Copper-chrom-arsenate treated softwood posts used as trellis support structures in 5 major horticultural districts of New Zealand were systematically examined for presence of decay. Principal crops on properties examined were grapes and kiwifruit; a minority of properties grew hops, boysenberries, and dwarf apples. Occurrence and severity of decay were variable within specific age classes of posts on individual properties and also between properties in the same region which had posts of similar age. Incidence of decay was higher in posts set in soils which were highly moisture retentive than in posts in drier areas or set in freely draining soils. Cross-sectional size and age of posts showed little correlation with frequency of severe decay, although the percentage of posts free of decay increased with decreasing age.
M E Hedley, J A Drysdale

New approaches to practical evaluation method of bio-degradation of wooden construction - Non-destructive detection of defects using radar technique
2000 - IRG/WP 00-20214
There have been a number of researches and developments on the techniques and apparatus for the nondestructive evaluation of the biological deterioration in wood and wooden constructions, such as decay or insect attack in house, public buildings or in historically important architectures. As for the detection of the decay in wood, techniques using sound in audible or in ultrasonic frequency ranges, stress waves, heat wave and X- ray have been investigated, where the changes in the physical properties expressed in the wave form were related to decay. The change in the velocity, the attenuation or the frequency spectrum of these physical energy waves can be associated with the decrease of the specific gravity or the structural change due to decay. Some mechanical properties such as the boring resistance and the elastic properties of wood surface could be an indicator of decay. The dielectric property of wood and its relation to decay is also useful. Miller et al. (1989) applied a radar technique to diagnosing of standing trees. However the techniques previously developed are not always feasible. One of the possible reasons is that these physical or mechanical properties change not only on decay but also on other factors, such as the water content or the grain direction in wood. In addition, sometimes the techniques are less practical, strictly not non- destructive or too expensive. In practical maintenance operation of wooden constructions, visual inspection together with sampling method plays an important roll, however a specialized training is needed for the operator to get the skill of the diagnosing. In this study, to establish a practical evaluation method of bio- degradation in wooden construction, scanning using a newly developed portable radar apparatus was investigated. By comparing the results with other methods, a more practical method to evaluate the bio-degradation in wood was proposed.
Y Fujii, Y Komatsu, Y Yanase, S Okumura, Y Imamura, M Tarumi, H Takiuchi, A Inai

Timber deterioration and its prevention in marine environment
2005 - IRG/WP 05-10559
Wood-borer activity is an established fact in Mumbai harbour that leads to severe deterioration of timber. In order to prevent the deterioration caused by wood borers three resin preservatives containing Zinc borate, Organo-copper polymer (4 wt% Cu) and Organo-Tin polymer Copoly(TBTM-MMA) were used for timber treatment. Test panels were treated using standard method and their efficacy was tested. It was observed that among three preservatives, panels treated with copoly (TBTM-MMA) with 10kg/m3 remained free from borer attack for 42 months, panels treated with Organo-copper polymer and Zinc borate, incorporated with chlorinated rubber (CR) have protected timber for 8 and 15 months respectively, as compared to control panels which were severely affected within three months. The study revealed that preservative containing TBTM as a toxic moiety can be used as an anti-borer preservative and protect the timber in marine environment over long period.
B S Swami, M Udhayakumar, P Kumar, A B Samui

An investigation of the factors influencing the rate of deterioration of timber samples due to microfungi in laboratory tests
1997 - IRG/WP 97-20116
An investigation was performed into the comparative performances of test 1 (vermiculite burial) and test 2 (soil burial) as described in ENV 807. Two test preservatives were used - copper naphthenate and propiconazole. Copper chromate was included as a reference preservative. The wood species used was beech (Fagus sylvatica). Test 1 was performed using both a mixed inoculation of the five stipulated softrot fungi, and separate monocultures of the test fungi. This enabled an assessment to be made of the individual performance of each fungus with the various preservative types, highlighting any incidence of preservative tolerance. Test 2 was performed as described in ENV 807. Isolations were made from test blocks in both tests where weight loss approached 3% m/m. In test 1 isolations were performed on samples from the mixed inoculation test, and in test 2 every 8 weeks throughout the 32 week duration. The results of this investigation show that the tests do not yield comparable results. Test 2 proved to be a more virulent system. The vermiculite test can only be relied upon when the microbial ecology of the treated wood in practice is known, as with copper naphthenate.
I J Herring, D J Dickinson, S M Gray, J K Carey

Study of the degradation caused by micro-organisms in Pinus sp. waterlogged wood
1989 - IRG/WP 1411
So far, the different Centers are trying the restoration and the conservation of wood structures, coming from subaquatic archeological deposits, with interest from the historic - artistic point of view. The main objective of this paper has been the determination of the decay level of Pinus sp. wood coming from a roman ship (approximately 2000 years old), where we have analyzed their physical properties, their chemical composition and the marine microorganisms (microfungi and bacteria) within.
M T De Troya, M C Escorial, J Garcia, A Cabanas

Some studies on fungal deterioration of rubber wood (Hevea brasiliensis)
1980 - IRG/WP 2140
For the sreening of anti-stain chemicals trials with selected agricultural fungicides and new chemicals were carried out. Botryodiplodia theobromae, Aspergillus sp. and Penicillium sp. were used at test organisms. For testing the durability of rubber wood (Hevea brasiliensis) suitable local rotting fungi (Basidiomycetes), based on high degrading power, which may later be employed in standard tests, were isolated: Trametes corrugata, Schizophyllum commune, Lentinus blepharodes, Lenzites palisotii, Ganoderma applanatum, Fomes senex and Polyporus zonalis. Several of the fungicides screened, such as benomyl, thiram, quintozene and captafol, are effective against the blue stain fungus Botryodiplodia theobromae, at fairly low concentrations. However at the levels required, none of them is cost-effective compared sodium pentachlorophenoxide, the preservative currently used for blue stain control in rubber wood. Of the seven Basidiomycetes tested, two of them - Lenzites palisotii and Ganoderma applanatum - were shown to give a high degree of degradation in rubber wood. These species could perhaps be used as test organisms for evaluating wood preservatives in Malaysia.
A Sujan, A G Tan, M Stevens

Deterioration of wood viewed from iron nail
1991 - IRG/WP 2368
Deterioration of nail was graded by a five - rank numerical - rating. The rating of nail moisture content and decay of wood were inspected in a mortal-wall of 34-year-old house. The wood was mostly in decay, when the rating of the nail was above about 4, and the moisture content was above about 20%. Nailed wood specimens kept in several humidity room of 20°C for 4 years showed that the rating of the nail was about 3 in the wood with moisture content 20%. A curve of the rating of the nail against the service year was obtained from the inspection of 524 nails in the mortal-wall. This curve could be a standard life curve of the nail in mortal-wall in the central part of Japan. The curve obtained by connecting the points (4 years, rating 3) and (34 years, rating 4) may be a wood decay warning line in terms of high moisture content. Shear tests for deteriorated nailed joints showed that the load was expressed as function of the slip and the amount of the rust of the nail. The nail used for bevel siding wall is more likely to be influenced by the environmental factors. From the inspection of the nail, the northerly wind was found to be influential to the deterioration the nail in an area of Tokyo.
H Imamura

Effects of air-seasoning on fungal colonization and wood strength of Douglas fir poles
1987 - IRG/WP 1315
Air seasoning economically reduces the moisture content of Douglas fir poles before pressure treatment with preservatives. Advanced decay in poles in service has resulted when decay fungi (Basidiomycetes) colonized poles during air-seasoning and survived the treatment process. These problems have led to recommendations to severely limit this practice. To determine the role of these fungi in peeled and unpeeled Douglas fir poles during air-seasoning in the Pacific Northwest, we identified many of the fungi involved, measured their effect on wood strength, and studied methods for limiting fungal colonization. Over 90 percent of peeled poles air-dried for more than 1 year contained decay fungi, suggesting that air-seasoning in the Pacific Northwest might pose some hazard; however, no significant strength losses were noted in poles dried 1 to 2 years. Poles seasoned for 3 years began to show significant strength losses, but these strength values fell within suggested design parameters for Douglas fir poles. Although Douglas fir poles are colonized by decay fungi as they dry, our results indicate that these fungi do not cause serious damage for at least 2 years. On the basic of these results, we recommend that poles be air dried no longer than 3 years in the Pacific Northwest. We also emphasize the importance of heating air-seasoned wood adequately during the treatment process to kill any fungi present.
J J Morrell, M E Corden, R D Graham, B L Kropp, P Przybylowicz, S M Smith, C A Sexton

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