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Laboratory decay test of Burmese in and kanyin treated with three wood preservatives
1982 - IRG/WP 3210
Laboratory decay tests were performed on samples of In (Dipterocarpus tuberculatus Roxb.) and Kanyin (Dipterocarpus alatus Roxb. and Dipterocarpus turbinatus Gaertn f.) pressure treated with three wood preservatives - copper arsenic additive (CAA - a variation of ammoniacal copper arsenate), Arquad C-33 (a waterborne quaternary ammonium formulation), and tributyltin acetate (TBTA) dissolved in ethanol. Pressure treatments with each preservative involved a 0.5 - 1 hour vacuum followed by a 4 hour period of pressure. This resulted in a very variable treatment because of the inherent difficulty in treating these woods. The decay tests entailed a slightly modified form of the AWPA M10-77 standard soil-block test using three brown-rot and three white-rot fungi. The untreated In and Kanyin samples were moderately susceptible to decay though weight losses were very variable and some samples of Kanyin (usually the densest and least permeable) were naturally resistant. At the concentrations tested CAA was the most effective in reducing weight losses incurred in the soil-block tests. TBTA was successful in controlling decay caused by all but two of the test fungi. It is suggested that preservative retentions for TBTA conforming to those included in the Candadian standard for bis (tributyltin) oxide would exceed the toxic limit for all the fungi tested
J N R Ruddick, R S Smith, A Byrne


Termiticidal chemicals derived from tropical tree resins
1991 - IRG/WP 1477
To test the hypothesis that defensive chemicals protect tropical primary forest trees against biological attack, a bioassay and fractionation program was conducted in Indonesia. Fresh dipterocarp resins were fed in no-choice tests to Neotermes dalbergiae termites on 4.5 cm filter papers, or tested for inhibition of fungal growth. Fractionation of biologically active resins via flash column chromatography, followed by subsequent bioassay and analytical chemical studies, revealed that several sesquiterpene compounds inhibited fungal growth and killed 50% of test termites in 3-7 days. Toxic fractions contained caryophyllene, caryophyllene oxide, alloaromadendrene, and other compounds. From the relatively non-toxic a-gurjunene, novel termiticidal compounds were synthesized, indicating the potential for manufacture of insecticides from natural products.
A Messer, K McCormick, D Richardson, Sunjaya, H Hagedorn, J Meinwald


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


Soft rot test of copper/chrome/arsenic treated heartwood of three Malaysian timbers
1991 - IRG/WP 2381
Standardized heartwood blocks of kempas (Koompassia malaccensis), keruing (Dipterocarpus sp.) and tualang (Koompassia excelsa) were impregnated with 0 to 6.3% (w/v) CCA and challenged to decay by a mixed inocula of Chaetomium globosum, Glenospora graphii, Humicola grisea, Petriella setifera and Trichurus spiralis in a containerized vermiculite-burial decay system according to draft CEN/TC 38 WG 4. A similar burial test using unsterile garden soil was included for comparison. The results of a preliminary assessment of a 12 w experiment were recorded (IRG/WP/2354). Due to low mass losses and final block moisture contents after the standard 12 w incubation, the experiments were resumed with the same samples and the above outlined culture conditions. Untreated European beech wood (Fagus sylvatica L.) was included as reference species. The experiments continued until beech samples reached 25% mass loss in soil-burial test (36 w). Final results are presented and the adaptation of draft EN soft rot test for treated tropical hardwoods are discussed.
A H H Wong, R-D Peek


Effect of wood species on decomposition efficiency of metham sodium
1992 - IRG/WP 92-3699
The effect of wood species and temperature on efficiency of metham sodium (32.1% sodium N-methyldithiocarbamate) decomposition to methylisothiocyanate (MITC) was investigated on 10 hardwoods and 9 conifers over a 144 hour period. Gas chromatographic analyses of headspace samples and ethyl acetate extracts of the wood revealed that decomposition never approached the theoretical decomposition efficiency (40%). Decomposition was generally better with hardwoods and at higher temperatures, although there were exceptions with some species. The results suggest that there is some potential for improving the performance of metham sodium through the use of additives which enhance decomposition efficiency.
J J Morrell


Soluble nutrient influences on toxicity and permanence of CCA preservatives in wood
1980 - IRG/WP 3144
The influence of soluble carbohydrate and nitrogenous components concentrated at evaporative surfaces of wood on the toxicity and permanence of CCA preservatives has been examined using soil-burial techniques. Nutrient concentrations in lime (Tilia vulgaris Hayne) have been shown to be associated with reduction of toxic limits of preservatives to an extent in which a 100% increase in preservative loading is required to provide adequate protection in the presence of soluble nutrient gradients. Toxic limit reduction was seen to be accompanied by nitrogen increases. The latter were attributed to microbial biomass which suggests a significant involvement of sacrificial colonisation by micro organisms. Preliminary analyses of elemental copper and chrome indicate an associated preservative instability.
B King, G M Smith, A Bruce


An environmental aspect relating to leachability of CCA from hardwood and softwood poles in Bangladesh
2001 - IRG/WP 01-50167
Leachability of CCA and the service performance of 8 softwood and 5 heartwood poles in service after 5 to 17 years in Bangladesh have been studied. The study included determination of retention of CCA-C in outer 6 mm zones at groundline (GL) and above groundline (AGL) along with the observation of decay and conditions of soils. The mean leaching of CCA-C derived from retention differential at GL and AGL are not found to be statistically significant. The existing balances of CCA-C components in poles do not indicate any leaching loss occurred. Reductions in retention have been noted at GL of softwood poles and at AGL of hardwood poles. Among several possibilities the density of wood as well as wood species/types, levels of retention, conditions of soil are found to be the prime factors which may increase leaching/depletion of CCA from the GL of softwood poles and responsible for poor performance of hardwood poles. The levels of CCA retentions in hardwood poles are not found to be adequate and equivalent to the levels of softwood poles in use. The CCA retentions of softwood poles were found still well above the toxic threshold for decay in even the oldest poles. Remedial treatments at GL of CCA-C treated hardwood poles installed in Bangladesh have been found to be essential. Very good service conditions confirm no remedial treatment necessary for CCA treated softwood poles.
A K Lahiry


Micromorphology of decay in Keruing heartwood by the basidiomycetes Phellinus contiguus and Dacrymyces stillatus
2002 - IRG/WP 02-10454
This study aimed to characterise the micromorphology of fungal decay in a wooden handrailing in an above ground exposure at the Thames embankment in London. Keruing heartwood (Dipterocarpus spp.) was determined as the construction timber and the two basidiomycetes Phellinus contiguus and Dacrymyces stillatus identified as main decay organisms. Their decay patterns within Keruing heartwood were studied using light microscopy. Besides typical white and brown rot decay features the analysis also revealed cavities in the fibre S2 wall layers. A laboratory screening test with monocultures of both fungi confirmed their individual ability to form rhomboidal shaped cavities similar to those commonly associated with “true” soft rot fungi. This form of attack indicates that typical soft rot-like cavities can also be formed by white and brown rotting basidiomycetes facultatively and are therefore not an absolute indication for the occurrence of soft rot causing asco- and deuteromycetes respectively.
G Kleist, M Ray, R J Murphy


Effectiveness of wood preservatives and treatments against marine borers in Philippine waters
1976 - IRG/WP 416
A 5-year exposure test was conducted on the effectiveness of wood preservatives and treatments against marine borers in Philippine waters. Air-dried heartwood samples of apitong (Dipterocarpus grandiflorus) 76.2 x 88.9 x 609.6 mm³ (3 x 3.5 x 24 in³) in size were pressure treated with coal tar creosote and two types of CCA (copper/chrome/arsenic) and CuCZA (copperized chromated zinc arsenate) waterborne preservatives. Average retention for creosote was 232.8 kg/m³ (14.5 lb/ft³). The dry salt retentions for the water-borne preservatives were CCA (A) 6.74 and 9.14 kg/m³; CCA (B) 8.01 and 12.04 kg/m³; and CuCZA 6.13 and 9.33 kg/m³ respectively. The first set of these treated specimens including untreated controls was exposed to marine borers at the Philippine Navy Ship Repair Yard in Cavite City in 1961 and another set a year later. Inspections were made at 6-monthly intervals. Preservatives CCA (A) and CuCZA at the two retention levels used and CCA (B) at the higher retention favourably oompared in performance with creosote at 14.5 lb/ft³ against marine borer infestations. The untreated apitong specimens incurred 75% deterioration after 9 months while the treated specimens attained the same degree of attack after 3.5 to 4.75 years. One of the CCA preservatives and creosote used in double-treating wooden test frames appeared to have conferred better protection than any of the water-borne preservatives tested. Martesia borers were more destructive and active than Limnoria in the test site. Martesia were active throughout the year, while the Limnoria appeared prevalent during the warmer months.
F R Siriban, M G Laxamana, P G Mata