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Organic solvent preservatives. Essays on the ecotoxicology of new formulations
1991 - IRG/WP 3642
The knowledge on the ecotoxicological profile of wood preservatives become more and more important. The acute toxicity against aquatic organisms was examined for oil-borne preservatives, based on combinations of new fungicides (Tebuconazole, Propiconazole, Dichlofluanid) and insecticides (Permethrin, Cyfluthrin). These tests were conducted with fish, daphnia and algae. In principle the different formulations showed similar effects. The results of active ingredients and solvents confirmed the high sensitiveness of daphnia as test organisms. Criteria for hazards for the environment are presented and discussed.
H-W Wegen

Evaluation of new creosote formulations after extended exposures in fungal cellar tests and field plot tests
2000 - IRG/WP 00-30228
Although creosote, or coal tar creosote, has been the choice of preservative treatment for the railroad industry since the 1920s, exuding or "bleeding" on the surface of creosote-treated products has been one incentive for further enhancements in creosote production and utility (Crawford et al., 2000). To minimize this exuding problem, laboratories such as Koppers Industries Inc., USA, and Commonwealth Scientific and Industrial Research Organization (CSIRO), Division of Chemical and Wood Technology, Melbourne, Australia, have developed changes in processing of coal tar that produce distillates with fewer contaminants. This "clean distillate" is then used to formulate "clean creosote" as a preservative. These new, unique creosote formulations are being investigated as part of a program to enhance the use of regionally important wood species in the United States. Four retention levels of each of two new creosote formulations creosote, one pigment-emulsified creosote (PEC) and one creosote formulation that meets the AWPA Standard C2-95 for P1/P13 creosote (AWPA, 1995a), were applied to two softwood species and two hardwood species. Two laboratory procedures, the soil-block and fungal cellar tests (accelerated field simulator), were used to evaluate the four creosote formulations. These procedures characterized the effectiveness of the wood preservatives. The soil-block tests were used to determine the minimum threshold level of the preservative necessary to inhibit decay by pure cultures of decay fungi. In general, the soil block tests showed there was little difference in the ability of the four creosote formulations to prevent decay at the three highest retention levels as summarized in a previous report by Crawford and DeGroot (1996). The soil-block tests will not be discussed in this report. Fungal cellar tests expose treated wood to mixtures of soil-borne fungi that promote accelerated attack. Crawford and DeGroot (1996) discussed the evaluation of the creosote formulations after 17 months of exposure in the USDA Forest Service, Forest Products Laboratory (FPL), fungal cellar. At that point in time data from the fungal cellar tests showed that softwoods are protected better than hardwoods for all four formulations of creosote tested. This report will discuss exposure of the fungal cellar stakes upto 36 months. In addition, field stake tests are being used to verify service life of the new creosote formulations in vivo. Results from accelerated tests are indicative of field performance, but the correlation between laboratory and field results is still being investigated. Field stake tests are regarded as critical, long-term evaluations that provide results most directly related to the performance of treated products in service. In this study, we report on the performance of the creosote formulations after five years of exposure in field tests.
D M Crawford, P K Lebow, R C De Groot

Current techniques for screening initial formulations against Basidiomycetes and soft rot
1978 - IRG/WP 2103
J D Thornton, H Greaves

In-ground performance of two formulations of chlorothalonil after five years of exposure at three test sites in Australia
1996 - IRG/WP 96-30101
Sapwood specimens of Pinus radiata D. Don and Eucalyptus regnans F. Muell. were each treated to three retentions of each of two preservative formulations (chlorothalonil in oil; chlorothalonil plus chlorpyrifos in oil) and installed in-ground at three field test sites in Australia. Specimens were treated with each formulation to achieve 3.2, 6.4 and 12.8 kg/m³ of chlorothalonil a.i. and 3.2 + 0.2, 6.4 + 0.4 and 12.8 + 0.8 kg/m³ of chlorothalonil plus chlorpyrifos a.i. For comparison, specimens of each timber species, treated to a commercial in-ground retention of a copper-chromium-arsenic (CCA) formulation, were also installed. Treated specimens (including controls) have been rated for their condition annually for attack by subterranean termites and fungal decay using a scale ranging from 4 (sound) down to 0 (failed). After five years of exposure, mean termite and decay scores for replicate test specimens at each site reveal that the performance of all three retentions of each formulation, particularly the two highest retentions, is comparable to CCA.
J W Creffield, T L Woods, N Chew

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

Chapter 6 - Preservatives of bamboo
2007 - IRG/WP 07-10635-06
Almost all currently available oil-borne, water-borne and compound types of preservatives suitable for the preservation of bamboo or wood have been described along with their classifications, applications, formulations, merits and demerits, history of invention or discovery and development. The preservatives suitable for wood are also considered suitable for bamboo.
A K Lahiry

Copper based water-borne preservatives: The biological performance of wood treated with various formulations
1987 - IRG/WP 3451
Wood samples treated with the various components of CCA preservative singly and in combination were tested against a soft rot organism, a copper tolerant brown rot organism and in soil burial both unleached and after leaching. The results suggest that, of the elements tested, fixed copper is essential for preventing soft rot attack and fixed arsenic is essential for preventing attack by a copper tolerant brown rot organism in leaching environments.
S M Gray, D J Dickinson

Potential toxicants for controlling soft rot in preservative treated hardwoods. Part 4: Evaluation of combined diffusion and toxicity
1979 - IRG/WP 2129
A large number of inorganic and organic preservatives were evaluated as potential soft rot control chemicals, by their degree of inhibition of fungal growth after allowing them to diffuse through a 6 mm thick wood slab. The tests were inoculated with wood powder from soft-rotted CCA treated poles. Pentachlorophenol was unable to diffuse quickly through the wood slab, although formulations with hexylene glycol showed some promise. Hydroxyisoxazole gave good results as did a number of other organic materials including "Busan 30", "Busan 52", "Permapruf T", sodium oxinate, sodium trichlorophenate, "Gloquat C", „Hyamine 1622", butyl icinol, and the commercial bandage materials "Osmoplast" and "Wolman pole bandage". Of the inorganic materials tested, good results were obtained with "Basilit BFB", with other Cu-F-B formulations including "Blue 7", and with fluoroborate and fluorosilicate preparations in general. Arsenates also showed some promise.
E W B Da Costa, O Collett

Preliminary screening of diffusion formulations for the control of soft rot
1978 - IRG/WP 2104
We have an urgent need in Australia to develop in situ remedial treatments for the present population of in-service transmission poles. For various reasons we have opted for formulations which can be applied as bandage treatments and thus we are primarily concerned with assaying diffusable toxicants. Two basic approaches have been made: an assay of the formulation's toxicity; and a combination assay of the formulation's diffusibility and toxicity. Of the direct assay methods the filter-paper technique is the more rapid although with highly soluble formulations some leaching of toxicants will occur during the preparatory stages and probably during incubation also. Furthermore, filter papers are not strictly comparable to wood, and a modification we have considered is to use 'papers' prepared from mechanically beaten pulps rather than chemically degraded pulps. An additional modification would be to substitute veneers for filter papers, although this may give rise to surface concentration effects since the veneers could prove difficult to impregnate homogeneously. By far the most valuable technique for our own screening programme of potential toxicants to control soft rot in standing poles is the Petri dish/wood slab technique. While agar diffusion systems are rapid and provide valuable 'short list' data, the information obtained on diffusion rates cannot easily be applied to solid wood. Da Costa's slab technique is obviously advantageous in this respect. Furthermore, it can be so tailored that successive inocula can be sequentially assessed, thereby providing added information on component diffusion as well as total formulation movement. However, care must be taken in interpreting the data since it is not possible to distinguish directly which chemicals in a mult-component formulation have diffused first and hence which are the toxic ones. Similarly, it could be necessary to impose a time restriction on the test with certain types of formulations.
H Greaves

Laboratory bioassay on the termiticidal efficacy of two ACQ formulations
1999 - IRG/WP 99-30199
The termiticidal efficacy of two ammoniacal copper quaternary ammonium formulations (ACQ) was evaluated in a laboratory bioassay using two species of subterranean termites, Mastotermes darwiniensis Froggatt and Coptotermes acinaciformis (Froggatt). Five retentions (1.0, 2.0, 4.0, 6.0 and 8.0 kg/m3 of active ingredient) of each ACQ formulation (MitrexACQ and ACQ97) were assessed in sapwood specimens of the softwood Pinus radiata D. Don and compared with the same retentions of the conventional benchmark preservative CCA (Tanalith C). All specimens (including controls) were subjected to an artificial weathering schedule prior to the bioassay. Under the conditions of the laboratory bioassay, both MitrexACQ and ACQ97 showed considerable potential as water-borne preservatives for preventing significant attack of P. radiata sapwood from two of Australia's most economically significant species of termite. At each of the retentions tested, MitrexACQ and ACQ97 performed comparably or better than equivalent retentions of CCA.
J W Creffield, A F Preston, N Chew

Long-term protection of stored lumber against mould, stain, and specifically decay: A comparative field test of fungicidal formulations
1984 - IRG/WP 3281
The problem of decay in packaged, unseasoned lumber stored for many months has become of major importance in recent years. Large financial claims have resulted from decay in Canadian lumber stored at length in seaports and storage yards of distributors. For decades acceptable protection from moulds and sapstain was readily achieved with chlorinated phenols applied at appropriate treating levels. However, in recent years, the use of chlorinated phenols in sawmills has become controversial, out of concern for its persistance in the environment and because of its broad spectrum of toxicity to practically all organisms. Although it was realized that this toxicity to humans had been over-emphasized, the discovery of traces of chlorinated dibenzodioxins as a minor impurity of some chlorinated phenols has generated further pressure to abandon the use of the latter. Forintek Canada Corp. has done extensive laboratory and field testing of fungicides for the lumber industry. Most of the field experiments were four-month studies (1) although one dealt with a two year evaluation of preservative retention and protection (2). In June 1981, under contract to Agriculture Canada, we began a field test of five new fungicidal formulations, comparing them with sodium tetra- and pentachlorpheates (NaTCP).
A J Cserjesi, A Byrne, E L Johnson

Laboratory evaluation of borate formulations as wood preservatves to control the subterranean termite coptotermes acinaciformis (isoptera: Rhinotermitidae) in Australia
2001 - IRG/WP 01-30266
The termiticidal efficacy of Borocol (sodium octaborate tetrahydrate), boric acid, bore-ester-7 and tri- methyl borate was evaluated in laboratory bioassays against Coptotermes acinaciformis (Froggatt). Seasoned sapwood blocks of Pinus radiata D. Don, and Eucalyptus regnans (F. Muell) were impregnated with the various borate compounds. There were marked differences in mass loss and mortality rate of the termite used in the bioassay units for different boron retentions. After 8 weeks the result suggested that, borate was toxic to termites in laboratory bioassay even at 0.20% m/m BAE and caused significant termite mortality. However, termites were not deterred from attacking the borate treated timber at higher retentions of > 2.0% m/m BAE. These laboratory results indicated that the minimum borate treatment required to protect timber against termites attack and damage was > 1.0% m/m BAE.
B M Ahmed, J R J French, P Vinden

Fungicidal activity of some new water borne copper octanoate based formulations
1999 - IRG/WP 99-30198
Four new water borne formulations for preservation of wood were prepared: the composition of Cu(II) octanoate, 2-aminoethanol (ethanolamine) and water; the composition of complex of Cu(II) octanoate with nicotinamide, 2-aminoethanol and water; the one of Cu(II) octanoate, organic boron complex, 2-aminoethanol, dimethyl sulfoxide and water and finally, the mixture of Cu(II) octanoate, diazene, 2-aminoethanol and water. Fungicidal activity of these new formulations against Trametes versicolor, Antrodia vaillantii and Coniophora puteana was determined by filter paper and mini-block test methods. Compared to the commercially used wood preservative containing Cu(II) naphthenate / Cu(II) 2-ethylhexanoate, the new compositions have stronger fungicidal activity. The strongest biocidal activity was exhibited by the formulation with a Cu(II) octanoate/nicotinamide complex.
M Petric, M Pavlic, F Pohleven, P Segedin, B Kozlevcar, S Polanc, B Stefane, R Lenarsic

Which fungi should be included in the laboratory evaluation of anti-stain chemicals?
2001 - IRG/WP 01-20236
Test fungi for efficacy tests of anti-stain formulations were selected based on the assumptions that test fungi should be fungicide-tolerant antagonists and fungi resistant to both fungicides and fungicide- tolerant antagonists, and such fungi should be re-isolated from treated samples with the highest fungicidal concentration used for laboratory evaluation of fungicides. This paper discusses the results of the study performed to assess the above assumptions using the fungi re-isolated from treated samples used for the laboratory efficacy tests of NP-1 Plus against all fungal isolates from green radiata pine logs.
Hyung-Jun Kim, Jae-Jin Kim, Gyu-Hyeok Kim

Penetration of surface applied deltamethrin micro-emulsion formulations in four European timber species
1994 - IRG/WP 94-20030
The Netherland's Government, in line with many other European Governments initiated a programme (KWS2000) aimed at significantly reducing the emission of volatile organic compounds by the year 2000. As part of this programme a research project is currently underway to evaluate the potential for replacing organic solvent based remedial treatments with micro-emulsion formulations of the same or enhanced insecticidal activity. To date the project has evaluated the penetration of a deltamethrin micro-emulsion formulation in four species, notably, Scots pine (Pinus sylvestris) sapwood and heartwood, Norway spruce (Picea abies) heartwood, Douglas fir (Pseudotsuga menziesii) heartwood and European oak (Quercus petraea) heartwood. The test method used, an adapted version of the German standard DIN 52 162, subsequent a.i. distribution analyses and results are discussed.
P Esser, W L D Suitela, A J Pendlebury

Analysis of water repellents in wood treated with water borne formulations using FTIR
2000 - IRG/WP 00-40176
The use of aqueous water repellent emulsion formulations has increased significantly in the wood treatment industry. These products are primarily used to enhance the weathering characteristics of wood products treated with water borne preservatives systems used in exterior above ground applications. They are also used in pole treatments to improve climbing characteristics and in low VOC millwork treatments. With the increasing usage of such products. there has been a need to develop analytical methods for the determination of the water repellent in treated wood products to ensure product quality and to aid in the development of enhanced water repellent formulations. A method for the determination of the water repellent concentration in wood was developed using Fourier transform infrared spectroscopy (FTIR). The wood samples were extracted and prepared for the FTIR scans using a liquid cell. The water repellent concentration was determined by using the intensity of the hydrocarbon C-H stretch adsorption. Methods for correcting or eliminating the interference from non-water repellent components in the wood extracts were developed.
P J Walcheski, L Jin

Field performance of novel antisapstain formulations
1997 - IRG/WP 97-30125
The effectiveness as antisapstain formulations of combinations of oxine copper (Cu-8), carbendazim, hexaconazole, cyproconazole, flusilazole, didecyldimethyl ammonium chloride (DDAC), an alkanolamine borate (SB), benzalkonium chloride (BAC), 2-n-octylisothiazolin -3-one (isothiazoline) and p-chlorophenyl-3-iodopropagilformal (CPIPF) was determined for freshly sawn, block-stacked radiata pine in three 18-week field trials: 1. Established in summer 1992 evaluating combinations of hexaconazole, carbendazim and DDAC. 2. Established in autumn/winter 1994 evaluating combinations of hexaconazole, carbendazim, DDAC, BAC and SB. 3. Established in autumn/winter 1995 evaluating combinations of triazoles, DDAC, Cu-8, carbendazim, CPIPF, isothiazoline and SB. Reference standards included: Cu-8; Cu-8 + carbendazim; IPBC + DDAC and TCMTB. In all tests, formulations containing carbendazim + hexaconazole + DDAC gave better protection for 12 and 18 weeks than most other experimental formulations and were equal to or better than commercial standards.
D R Eden, R N Wakeling, C M Chittenden, J G Van der Waals

An evaluation of the synthetic pyrethroid cypermethrin in organic solvent and emulsion formulations
1984 - IRG/WP 3290
The studies reported indicate that cypermethrin (NRDC 149) has considerable potential as an insecticide for wood preservatives. Cypermethrin appears to be about twice as effective as permethrin. The effectiveness of cypermethrin compared with g-HCH varies depending on the insect species, the phase of the life cycle and size of larva: for example, against mature Anobium larvae cypermethrin is approximately equal to g-HCH in effectiveness, but against egg larvae it is four times more effective. Against emergence of Anobium adults an organic solvent formulation containing 0.1% cypermethrin was more effective at 16 months than the g-HCH solution which was ten times stronger. Against mature Hylotrupes larvae it is approximately four times more active than g-HCH but as a surface spray against Lyctus a concentration of cypermethrin fifty times less than that used commercially for g-HCH spray treatments prevented infestation. Bioassay tests with a range of wood-boring insects reveal broad spectrum activity and considerable resistance to standardised accelerated evaporative ageing. In emulsion formulation cypermethrin at 0.1% prevented emergence of Anobium adults for 5 years, and was effective against attack by termites. A 0.01% emulsion formulation prevented infestation by Lyctus. In organic solvent formulation 0.1% cypermethrin gave an acceptable level of mortality against both Anobium and Hylotrupes larvae and prevented emergence of Anobium adults at 26 months.
S J Read, R W Berry

Laboratory and Pilot Evaluation of Chlorothalonil Formulations for Mold and Stain Control on some Wood Species
2003 - IRG/WP 03-30317
Laboratory and pilot test of the efficacy of several fungicides such as chlorothalonil and carbendazim for control of mold and sap- stain on bamboo and slash pine and rubberwood were conducted in this paper. The result indicates that: -- Clorothalonil/carbendazim are more effective for controlling mold and stain than that of carbendazim alone in laboratory test. --Higher concentration at 0.1-0.2% of chlorothalonil with 0.05-0.1% carbendazim or 0.05-0.1% carbendazim alone are more effective for stain and mold control on slash pine than the formulations of lower concentration in the pilot test. The mixture formulations of 0.1-0.5% clorothalonil/carbendazim are more effective than 0.5%NaPCP or 0.2% carbendazim alone in controlling mold and fungi in rubberwood pilot test.
Mingliang Jiang, Zhaobang Li

The performance of metal-chromium-arsenic formulations after 32 to 38 years' in-ground exposure in Australia
2000 - IRG/WP 00-30240
Two trials of metal-chromium-arsenic preservatives were exposed in-ground in Australia. In Trial 1, Pinus radiata stakes treated with Boliden K.33, Boliden S.25, Celcure A, Tanalith C and Tanalith CA were installed at Sydney and Narrandera in 1961/1962. In Trial 2, P. radiata and Eucalyptus regnans sapwood were treated with Celcure A, Celcure A21-N, Celcure A 21-O and Tanalith CA (new) and installed at Sydney and Innisfail in 1966/1967. In Trial 1, all metal-chromium-arsenic preservatives at 8 and 12 kg m-3 gave median specimen lives in excess of 35 years. As none of the stakes treated to 12 kg m-3 with Boliden K.33, Celcure A, Tanalith C or Tanalith CA had become unserviceable, the minimum guarantee period for these preservatives is greater than the present exposure periods. In Trial 2, the four CCA preservatives when impregnated into P. radiata sapwood at 12 kg m-3 gave median specimen lives at Sydney of greater than 32.5 years. With E. regnans sapwood treated to 12 kg m-3, only Celcure A 21-0 gave a median specimen life at Sydney of greater than 32.5 years. At the high decay and termite hazard site of Innisfail, Celcure A 21-0 protected the eucalypt better than any of the other CCA formulations.
G C Johnson, J D Thornton, J Beesley

Laboratory and field trials of novel antisapstain formulations
1997 - IRG/WP 97-30146
This document covers the results of laboratory and field trials of combinations of fungicides formulated using a patented technology (PCT NZ 96/00143). A 3 week laboratory trial that uses radiata pine (Pinus radiata D. Don) branch discs as a substrate was used to determine which combinations possessed a suitable spectrum of fungitoxicity against key sapstain, mould and decay fungi. In particular fungitoxicity against Ophiostoma piceae H & P Syd was looked for as this is the most difficult fungus to control on freshly cut radiata pine in New Zealand. The most promising formulations were then tested using block stacked radiata pine stored for 11 weeks during a high hazard summer period. In general the field trial results corroborated with the laboratory disc trial results. The importance of a broad spectrum of fungitoxicity and in particular a high level of activity against O. piceae, was shown by both types of trial. A formulation containing hexaconazole (0.014%w/v) plus carbendazim (0.028%w/v) plus a quaternary ammonium compound (0.291%w/v) was particularly promising. This formulation achieved significantly better (5% level of probability) control than the commercial standards, for 11 weeks of summer storage. The low fungicide concentrations used auger well for it's cost effectiveness. It is believed that this was in part due to fungicide synergy, broad spectrum activity and the use of microemulsions and solutions of the key fungicide components.
R N Wakeling, P N Maynard, D R Eden, C M Chittenden, B Carpenter

Evaluation of chlorothalonil for stain and mould control on lumber
1992 - IRG/WP 92-3713
Chlorothalonil is a commercially important fungicide with many industrial and agricultural applications. It has a very low mammalian toxicity and is considered to be an environmentally benign material. This paper describes the laboratory evaluation of chlorothalonil as a wood antisapstain treatment. Chlorothalonil was tested as three formulation types - an emulsifiable concentrate (EC), a water-based flowable, and a micromilled (small particle size) flowable. In general, the EC had the best performance against surface growth of mold, stain, and Basidiomycete fungi. The activity of chlorothalonil against mold and stain fungi could be significantly enhanced by the incorporation of an additional fungicide. Copper-8-quinolinolate and diiodomethyl-p-tolylsulfone performed particularly well as complementary fungicides. Chlorothalonil was very effective by itself in controlling surface growth of Basidiomycetes. The chlorothalonil EC formulation performed better than or equal to sodium pentachlorophenate, except against the mold fungi, where the NaPCP was somewhat more effective at lower concentrations.
P E Laks, T L Woods, D L Richter

Surface retentions of PCP, TCMTB and MTC obtained during a field trial of antisapstain formulations
1993 - IRG/WP 93-20002
Formulations containing NaPCP or TCMTB and MTC were included as reference products in a recent field trial of antisapstain formulations in Queensland. Retentions of these actives on the surface of treated sawn Pinus elliottii were monitored by ultrasonic solvent extraction of excised samples and analytical determination by high performance liquid chromatography. Distribution of actives with depth and longitudinal position were monitored for the particular dipping/draining schedule employed, and related to dip concentration and time since dipping. The analytical data provide a direct measure of surface retention in terms of active ingredients per unit area, the assessment method preferred by WG II Sub-group 3 at IRG 23. Even if only applied to these reference treatments, such analysis would facilitate comparison between trials conducted using widely varying treatment regimes and conditions.
D E Ferlazzo, M D Needham, M J Kennedy

Comparison of the FRIM and forest research laboratory methods for screening of anti-sapstain formulations
1999 - IRG/WP 99-20170
Two laboratory methods for screening of anti-sapstain formulations were compared. The method adopted by the Forest Research Institute Malaysia (FRIM) involved 3 weeks assessment of rubberwood (Hevea brasiliensis) blocks, dipped in the candidate formulation and inoculated with mycelial/spore suspension of sapstain (Botryodiplodia theobromae) or decay (Schizophyllum commune) fungi, and incubated on moistened filter paper in sterile glass Petri plates. The Forest Research disc trial method assessed similarly treated radiata pine (Pinus radiata) branchwood discs inoculated with mycelial/spore suspension of sapstain (blended cultures of Shaeropsis sapinea, Alternaria sp. and Ophiostoma piliferum) or decay (S. commune) fungi, resting on toast racks in covered humidified sterile containers for 2 weeks. Five candidate formulations available in New Zealand, and sodium pentachlorophenate of common use in Malaysia, were screened using two slightly different rating methods both assessing percentage of fungal growth on infected wood. The results indicated no difference between rating criteria used, but revealed differences in the efficacy of a selection of these formulations between the test methods.
A H H Wong, D R Eden, C M Chittenden, M E Hedley, R N Wakeling

Performance of Tuff Brite C™ and other formulations against blue-stain, mold and brown-stain in freshly-sawn rubberwood (Hevea brasiliensis) in the humid tropics of Peninsular Malaysia
1997 - IRG/WP 97-30163
The relative anti-sapstain and anti-mold efficacies, including brown-stain development in freshly-sawn rubberwood (Hevea brasiliensis) in the Malaysian tropics, between selected water-based product concentrations of formulations Tuff Brite CTM without/with added Borax (at 1.5/0, 1/1.5, 1.5/1.5 and 2%/1.5%), PQ8TM without/with added Borax (at 2.5/0, 1.5/1.5, 2/1.5 and 2.5%/1.5%) and NeXgenTM/NeX-BriteTM combination (at 1/0.25, 1.5/0.25 and 2%/0.25%) were assessed visually. Rubberwood boards, dipped in these concentrations for 1 min. were subjected to an 8 weeks sapstain trial in a FRIM sawmill shed. Sodium pentachlorophenate/Borax combination (at 2/1.5 and 2%/2%) was the reference anti-sapstain chemical. The rough-sawn boards were rated for blue-stain and mold weekly, while both the planed and the internal faces of the boards, sawn lengthwise into two-halves, were rated for blue-and brown-stain only after 8 weeks. Results for the rough-sawn boards, planed boards and the internal faces of the boards revealed a generally consistent excellent performance of Tuff Brite CTM without/with Borax against blue-stain and mold in rubberwood, protection being marginally better than that of NaPCP/Borax. Over a range of concentrations, performance by the remaining fomulations PQ8TM without/with Borax and NeXgenTM/NeX-BriteTM were variable: rated satisfactory (generally <10% surface infected) and/or poor (31-50% of surface infected) against sapstain and/or mold. Against brown-stain development (i.e. to conserve the natural cream/yellow hue in rubberwood), Tuff Brite CTM without/withBorax also appeared to be relatively better (generally yellow-to-light brown hue) than the other formulations, but perhaps only marginally so than NaPCP/Borax (light blue as well as yellow-to-light brown hue observed).
A H H Wong, T L Woods

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