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Borate thermal treatments
1992 - IRG/WP 92-3715
Green, partially seasoned (air-dried, steam conditioned), or kiln-dried southern pine timbers were treated thermally using 15% disodiumoctaborate tetrahydrate solution. After treatment, sections were stored under non-drying conditions to allow for diffusion. Results showed that effective treatment meeting the AWPA minimum retention (0.17 B203 pcf [2.72 kg/m³] in the outer inch) and penetration (2.5-in [64-mm] or 85% of the sapwood) could be obtained only with certain combinations of seasoning, treatment, and diffusion storage. The best results in terms of both retention and penetration were obtained with material steamed and stored prior to treatment using a 10-min hot bath time. Kiln-dried timbers could not be treated effectively. The results suggest that non-conforming treatment of green or partially seasoned timbers will require higher solution concentrations, higher hot bath temperatures, and/or longer diffusion periods to meet required standards. Results also indicated that treatment of smaller stock in dimension sizes (up to 2-in [50-mm]) should be feasible.
H M Barnes, R W Landers, L H Williams


Preservative treatment of Pinus elliottii
1987 - IRG/WP 3435
The treatment of Pinus elliottii with copper-chrome-arsenic preservative by four alternative seasoning and treatment methods is investigated. Steam conditioning followed by either alternating pressure method (APM) or 'Q' treatment resulted in inadequate preservative penetration. Air drying or high temperature drying followed by the Bethell process resulted in a high standard of treatment.
P Vinden, L Carter


Survey of conditioning treatment practices in India
1978 - IRG/WP 3127
India has 75.3 million hectares (ie about 24% of total land area) under forests out of which the area of productive forests, from which industrial wood is available, is about 60 million ha. The Task Force on Forest Resources Survey has tentatively estimated that the total growing stock in Indian Forests is 24,000 million cubic metres (m³). The total recorded production of wood in the country is roughly estimated as 25 million m³ annually of which approximately 10 million m³ is demanded by various industries and the remaining is used as fuel. India, with developing economy needs very large resources of timbers for diverse purposes. There is already shortage of timber in the country for various wood based industries and it is expected this will progressively increase with the rapid pace of industrialisation. However, suitable measures are being taken to bridge the gap between demand and supply. The entire 10 m³ of industrial wood requires some sort of protection against wood-destroying agencies. Timber awaiting conversion during storage needs prophylactic treatment while for use as poles, fence posts, sleepers, building material, in cooling towers, boats, ships, in mines, in sea-water, etc., timber should be adequately treated with suitable wood preservatives to obtain satisfactory service life. Both heart and sapwood of non-durable species and only sapwood of durable species need protection against wood-destroying agencies. Wood Preservation on scientific and modern lines was introduced in India by Sir Ralph Pearson of the Indian Forest Service in the year 1908. In India, the first wood preservation plant was established at Bally in Howrah in 1854. Of the total timber extracted in India, only a very small proportion, estimated at about 5% is treated. This amounts to 0.45-0.50 million m³ of wood per annum. The total annual capacity of 140 preservation units, existing in the country at present, is estimated at 0.43 million m³ on single shift basis. IS: 401-1967 (Indian Standard - Code of Practice for Preservation of Timber) covers types of preservatives, their brief descriptions, methods of treatment, and the type and choice of treatment for different species of timber for a number of uses. This standard includes only such preservatives and methods of treatment which have given satisfactory results under Indian condition of service. According to this standard, whatever process of treatment is adopted, timber for treatment should be sound and should be dried to an appropriate moisture content (generally not more than 15% for open tank and 25% for pressure processes). All the wood working etc should be done prior to treatment. In case of timbers, specially some conifers having non-durable heartwood which is refractory to treatment, when treating thick members like railway sleepers, beams, piles, etc, incision of all the surfaces, other than the ends, to a depth of 12-20 mm is necessary.
M C Tewari


Fixation of CCA in Pinus sylvestris after kiln-drying
1990 - IRG/WP 3594
Tanalith C Paste is 98% fixed and Tanalith Oxide C is 99% fixed irrespective of whether treated Pinus sylvestris is kiln or air dried. A schedule suitable for kiln drying of CCA treated Pinus sylvestris is described.
P Warburton, J A Cornfield, D A Lewis, D G Anderson


Observations on the uptake and penetration of various liquids in clear heartwood and sapwood of Pinus radiata D.Don
1983 - IRG/WP 3224
Volumetric uptake of water (aqueous copper-chrome-arsenic (CCA)) or methanol, applied by bulk hydrostatic pressure to air dried clear heartwood specimens of Pinus radiata D. Don, far exceeds that of a wide variety of polar and non-polar solvents. In air dried sapwood, the volumetric uptake of CCA tends to be less than that achieved for most solvents including methanol. No comprehensive explanation of the penetration mechanism in these two substrates can yet be offered. High temperature drying effects a significant increase of volumetric uptake of all liquids by heartwood, but not by sapwood, possibly because air dried material is nearly saturated after pressure treatment.
J E Barnacle


A field test with anti-sapstain chemicals on sawn pine timber stored and seasoned under different conditions
1984 - IRG/WP 3245
Newly sawn timber of European redwood (Pinus sylvestris L.) was dip treated in four different anti-sapstain chemicals. The protectife effect against sapstain, mould and decay was examined after 10 weeks' and 10 months' storage in open and closed stacks. The results showed that the performance of individual chemicals was different in open and close stacks, although the wood as well as the other storage and handling conditions were identical. This makes it possible explain some of the reported differences in performance of chemicals in different locations.
D J Dickinson, B Henningsson


A note on te seasoning, preservative treatment and suitability of debdaru (Polyalthia longifolia Benth & Hooker.) for poles
1995 - IRG/WP 95-40056
The main work is to determining the suitability of Debdaru (Polyalthia longifolia Benth.) as poles from Government and Village forests are investigated. The poles of Debdaru are easily treatable with CCA preservative by full-cell pressure method, but difficult to dry (air & kiln). Proper quality control must be maintain from procurement to treatment, specially during physical selection & drying (air & kiln) otherwise it may be discard as pole. Debdaru poles have been found suitable for power and Telecomunication lines with very keen care.
G N M Ilias, M D Rokib-ul-Hafiz


Kiln drying of poles as a means of solving the problems of pre-treatment decay in poles
1985 - IRG/WP 1263
The concept that pre-treatment decay can cause wide variation in the treatability of wood and especially wood poles has caused much discussion and debate in wood preservation circles. Yet it seem only logical that if decay has effected the strength characteristics of the wood and caused a differential moisture content in the wood the treatment of the end product will be highly variable and the longevity of the product will be unpredictable. Quite simply the one proven solution to the problem seems to be to artificially season the wood, usually by kiln drying, prior to treatment. This paper briefly reviews 1984 observations of the success of one treating operation in the Republic of South Africa in reducing the deterioration found during proof loading of all the poles produced. A literature survey is included to review the research accomplished to date to show that the results are truly valid. It is hoped that this paper will serve as a literature reference to other researchers in this subject and that they will contribute their findings to the work of the working group on pre-treatment decay in wood.
J A Taylor


The effect of preservative distribution in small blocks of Pinus sylvestris on the toxicity of tributyltin oxide to Reticulitermes santonensis Feytaud
1971 - IRG/WP 206
Small blocks of Pinus sylvestris (50x25x15 mm³) were treated by a full-cell method with various concentrations of tributyltin oxide in benzene. Replicate blocks were then freeze dried, rapidly air dried or slowly air dried and exposed to surface attack by the subterranean moistwood termite Reticulitermes santonensis Feytaud. At all concentrations it was found that the freeze-dried blocks were more heavily attacked than the air-dried ones, and that a threshold value determined in the normal way using air-dried blocks could be much underestimated. This agrees with what one would expect from the uneven distribution of preservative produced by air drying compared with the uniform distribution obtained by freeze drying. The results with slow air drying were in between those obtained from the other two methods. Further work is required to check the value of this method.
M P Levi, D N R Smith


Pretreatment decay in air-seasoning Scots and Corsican pine poles in England
1989 - IRG/WP 1390
British grown Scots and Corsican pine poles were sampled for colonization by basidiomycetes after air-seasoning for 6 to 9, or 16 to 20 months. The amount of infection present in these poles was compared with that in poles which were imported from Finland. After 6 to 9 months seasoning, the British grown pine poles were heavily infected with Peniophora gigantea, Cylindrobasidium evolvens, Stereum sanguinolentum, and Heterobasidion annosum, which were isolated from about 35, 20, 10, and 6% of the increment cores sampled, respectively. In poles which had seasoned for 16 to 20 months, the frequency of isolation of Stereum sanguinolentum was much greater, while that of Cylindrobasidium evolvens had decreased. Poles imported from Finland were heavily colonized by Stereum sanguinolentum and Cylindrobasidium evolvens (40 and 35% of cores, respectively), but generally showed little colonization by Peniophora gigantea and none by Heterobasidion annosum. The high incidence of Peniophora gigantea in British grown poles from forests where this fungus is used as a stump treatment to control Heterobasidion annosum may be cause for concern.
A R Zahora, D J Dickinson


Mould growth at lumber surfaces of pine after kiln and air drying
1994 - IRG/WP 94-40033
Distribution of water soluble substances in green wood and later redistribution during drying is of importance for the colonisation of wood by microorganisms. According to literature the availability of nitrogenous materials is probably a major limiting factor to the microbial colonisation of wood. King et al. (1974) and Oxley et al. (1976) have shown correlation between surface nutrient concentration and the degree of invasion by soft rot fungi. Although the effects of some factors on the susceptibility of wood to mould have been studied (Land 1986, Hallenberg and Gilert 1987, Bjurman 1989a, b), the effect of the drying treatment was not considered. In the study by Theander et al. (1993) it has been indicated that the growth of the mould fungi Penicillium brevicompactum and Aspergillus versicolor is positively correlated with the content of nitrogen and low-molecular carbohydrates. Kiln and air drying cause redistribution of the soluble sugars and nitrogen in different ways and the effect of kiln drying varies depending on the drying schedule (Terziev et al. 1993, Terziev 1994). The major goal of the present study was to investigate whether different drying treatments of wood (causing different redistribution of low-molecular sugars and nitrogen) create different susceptibility for mould growth. The material for the moulding tests was from the above mentioned studies of Terziev et al. (1993) and Terziev (1994). Thus, drying history and contents of soluble sugars and nitrogen were known for the test material. No data were found in the literature about mould growth after different drying treatments. The present experiment is to be considered as a preliminary study.
N Terziev, J Bjurman, J B Boutelje


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


Standardization of CCA treated 45 hardwood species grown in Bangladesh for REB crossarms
1995 - IRG/WP 95-20059
Researches on 45 hardwood species grown in Bangladesh regarding density, moduli of rupture (MOR), colour and treatability of sapwood and heartwood, seasoning property and natural durability of heartwood revealed that both sapwood and heartwood of 17 species could be full cell pressure treated with CCA at impregnation pressure of 14-18 kg/cm² and only sapwood of rest 28 species could be pressure treated. Hartwood of 28 species were found to be mostly refractory to treatment but naturally fairly durable to very durable when used indoor or overhead exposed conditions. The MOR of 45 timber species varied from 58-96 N/mm² at green conditions, sufficiently strong for distribution crossarms. The most dense timbers were found to be kilndried slowly and effectively. Inherent strength, conventional sawing, conventional grading with pilodyn, kilndrying before treatment and slow air-drying before outdoor storing upto EMC (19% MC) at centerline of crossarms and adequate CCA-C treatment in treatable areas would ensure long term utilization of these timbers in Rural Electric Systems in Bangladesh.
A K Lahiry


Co-operative tests concerning influence of solvent and drying method on the toxic limit of wood preservatives against Basidiomycetes. Preliminary report
1971 - IRG/WP 204
In the Working Group II of the Organization for Economic Co-operation and Development working group on wood preservation (now International Research Group on wood preservation) it was agreed that more knowledge was necessary concerning the influence of the solvent on the toxic limit of organic solvent types of wood preservatives against Basidiomycetes. A test program was drawn up and after discussion in the mentioned working group the final program was accepted by the co-operating institutes in 1969. In the test program two fungicides, a pentachlorophenol concentrate and tributyltinoxide, solved in four different solvents were enclosed. Considering that an influence of the kind of solvent could coincide with the rate of evaporation thereof from the test blocks, also different drying methods for some solvents were included.
T Hof


Survey of conditioning treatment practices in the Philippines
1975 - IRG/WP 349
The wood preservation industry in the Philippines is at present beset by many problems. An association of the industry similar to those existing in other countries has only been initiated last year by FORPRIDECOM. It is hoped that the formal organisation of this association will bring into focus the importance of this particular industry in the economic and industrial development of the country. Likewise, for the past years, treatment specifications suitable for Philippine conditions, wood species, and wood products are non-existent. Treatment specifications are usually patterned after those of other countries but in most cases, specifications of the American Wood Preservers' Association (AWPA) are generally followed regardless of whether they may or may not apply to our existing climatic conditions and to local wood species. It was only last year, however, that a series of discussions and formulations of acceptable treatment specifications had been started for which substantial progress is being made in co-operation with the private sectors.
R F Casin


Termite durability of sugi (Cryptomeria japonica) heartwood kiln-dried under high-temperature process in relation to wood extractives
2005 - IRG/WP 05-10547
Termite durability of sugi heartwood samples kiln-dried under a high-temperature process were evaluated by using Reticulitermes speratus (Kolbe) as a test termite sp. The n-hexane extractives of these samples were analysed by a GC technique. The less termite durability was shown on the wood samples dried under the high-temperature process, in comparison with that of the air-dried samples. No GC-peak assigning to cubebol and epicubebol was shown in n-hexane extractives of kiln-dried samples.
S Shibutani, E Obataya, K Hanata, S Doi


Co-operative tests concerning the influence of solvent and drying method on the toxic limit of wood preservatives against Coniophora cerebella
1972 - IRG/WP 216
In the working group II of the IRG it was agreed that more knowledge was necessary concerning the influence of the solvent on the toxic limit of organic solvent types of wood preservatives against Basidiomycetes. A test program was drawn up and after discussion in the mentioned working group the final program was accepted by the co-operating institutes in 1969. In the test program two fungicides, a pentachlorophenol concentrate and tributyltinoxide, solved in four different solvents were enclosed. Considering that an influence of the kind of solvent could coincide with the rate of evaporation thereof from the test blocks, also different drying methods were included for some solvents. Preliminary results of these co-operative tests have been given in a report presented on the meeting of the IRG Working group II in November 1971 in Brussels. At that time the tests were not yet completed and the results then available were not worked out in details. The complete test program is now finished and the results are given in this report.
T Hof


Pretreatment decay in poles of Pinus sylvestris
1987 - IRG/WP 1329
Storage damage by blue stain and decay in poles before impregnation has been increasingly observed during recent years and there have been reports that salt-impregnated poles today are of lower quality because of incipient decay being increasingly common. The attacks may have started at the time of cutting and then continued during the period of seasoning at the plant, which could be as long as two years. Sub-standard impregnation has been mentioned as a reason for the decay. However, microscopic examination of samples from newly-impregnated poles has shown that attacks of blue stain as well as of brown and white rot have sometimes been of such an extent that damage by micro-organisms before impregnation was the probable reason. The aim of the present work was to illustrate the extent of blue stain and rot in poles before impregnation and to survey the methods of bark removal and storing poles during seasoning in Sweden. The production of treated poles of pine (Pinus sylvestris L.) in Sweden during 1985 was 74,300 m³ (51,200 m³ with creosote and 23,100 m³ with water-borne). The amount exported was 27,900 m³ (26,100 m³ with creosote and 1,800 m³ with waterborne CCA-type). At the time of the investigation there were nine major impregnation plants for poles in Sweden.
H Lundström, M-L Edlund


Redistribution of boric acid in radiata pine during drying after preservative treatment
1993 - IRG/WP 93-40010
Samples of 100 x 50 mm² radiata pine were processed with a variety of options to produce dry, boron-treated wood. Concentrations of boric acid in the central one-ninth and in the whole of the wood cross-sections were determined by chemical analysis and compared. Diffusion treated material was dried by air, conventional kiln (70/60°C), or high temperature kiln (120/70°C). Four different predrying, pressure treatment, and redrying combinations were also evaluated, using a low net absorption (nominally 200 l/m³) treating process. Drying after diffusion treatment resulted in substantial redistribution of preservative towards the surface of the wood samples. In addition, a net loss of preservative from kiln-dried, diffusion-treated wood was observed. Pressure treated wood was much less affected. Mechanisms which may account for observations about the various processing options are postulated. Results are compared with those produced by Vapour Boron Process treatment of the same material. The advantages of this process are discussed, particularly in view of the recent extension of the New Zealand specifications for preservative treatment to include retention requirements for dry, boron-treated wood.
A J Bergervoet, D R Page, J A Drysdale


The control and pretreatment decay in air seasoning Scots and Corsican pine poles in England
1990 - IRG/WP 1451
Previous work clearly showed that air-seasoned, British grown Scots and Corsican pine poles are subject to serious pretreatment decay. In order to control these infections a range of pretreatments are currently being investigated. One series of treatments is designed not only to control decay but also allow the development of mould and stain fungi in order to achieve the desired increases in porosity prior to creosoting. The trial is due to run for a total of 18 months. The initial results have been very encouraging and due to the considerable current interest in this area the results for 6 and 12 month samplings are presented in this short preliminary report to the sub-group. Simple borate treatments have effectively prevented the development of basidiomycetes but allowed mould and stain development. This has led to the subsequent, desired porosity increases and initial creosote treatments appear very good.
D J Dickinson, A R Zahora, A P Dodson


The effects of accelerated drying of green Pinus radiata on its attractiveness to Anobium punctatum as an egg-laying site
1984 - IRG/WP 1199
The methods and results are given for a series of experiments in drying Pinus radiata sapwood under a variety of conditions, then exposing the material to Anobium punctatum egg-laying. The results showed very clearly that the attractiveness of the wood to gravid females was drastically reduced when dried from green at temperatures much above 35°C. Both simple oven drying and steam kilning produced the effect. Attempts to reverse the effect, or develop it in already seasoned wood, indicated that it was a phenomenon related to the green state, i.e. it could not be induced at any other time, and this in combination with special drying techniques results suggests that it is oxidative in character. On current evidence it seems unlikely that fungi/bacteria have a major role in the effect.
D J Cross


Influence of Copper Preservative Type on Earlywood and Latewood Distribution of Copper in Treated Wood
2010 - IRG/WP 10-40507
Some of the new water based copper containing wood preservative systems use particulate “micronized” copper as the primary biocide instead of the more traditional soluble amine copper based systems. Studies were conducted to investigate how this difference in the type of copper system might impact both initial and post drying distribution of the preservatives in wood. Of specific interest was to determine the influence of the copper type on the distribution in earlywood and latewood portions of southern pine lumber, where significant differences in wood density might impact preservative loadings for the soluble and particulate systems. Our results support that the copper distributions were distinctly different between the two systems in air-dried boards, although amine copper treated boards had a similar copper distribution immediately after treatment to that observed in dry micronized copper treated boards. Both the air-dried boards treated with micronized copper and the freshly treated amine copper treated boards had distinctly higher copper concentrations in the early wood bands than in the latewood bands on a wood mass basis. After air-drying, this difference is dramatically reduced in all but the outermost growth rings in the amine copper treated boards, suggesting some copper redistribution on drying, as well as copper binding to the wood substance in direct ratio to the amount of wood substance present.
A Zahora


Performance of kiln-dried and air-dried anti-sapstain treated pallet timber under use scenarios against wood discolouring fungi
2015 - IRG/WP 30669
During their lifespan there is a high probability that wooden pallets and packaging material will be exposed to rainfall or rewetting conditions, increasing the risk of growth of discolouring fungi. Kiln-drying of wooden pallets and packaging material without anti-sapstain treatment does not give efficient protection against wood discolouring fungi during rewetting periods. However additional temporary protection can be achieved, when pallets and packaging material are manufactured from timber treated with anti-sapstain preservatives. In order to compare the performance of kiln-dried pallets and air-dried pallets treated with an anti-sapstain preservative against blue-stain and mould infestation, three practical use scenarios of rewetting were investigated. The first scenario was the simulation of rainfall, followed by indoor storage under moist and warm conditions representing shipping of wet pallets in closed trucks or container. The second scenario simulates storage of humid goods or goods which can release moisture like, e.g., fruits or vegetables which have been stored under plastic foil in a changing temperature climate like e.g. during night and day. Condensed water can be formed on the foil building water droplets which will increase the wood moisture. The third scenario was the simulation of pallet movement of cooled goods from a cold storage warehouse into humid and warm climate area, studying the influence of the condensed water on the surface of a pre-cooled good, packed with foil on the pallet and subsequently stored or transported under high humidity and elevated temperature. The evaluation of the specimens was carried out by optical assessment according to CEN/TS 15082. After 28 days in all of the simulated scenarios the kiln-dried pallets were three times more affected by moulds and sapstain fungi than the pallets treated with anti-sapstain preservatives.
A Steitz, E Stoyanova, N Pfabigan, R Gründlinger


Solvent drying and preservation of timber
1977 - IRG/WP 381
Processes which combine drying and preservation are first reviewed. Some preliminary experiments are then described in which blocks of green Sitka spruce sapwood were immersed, in a solution of tributyltin oxide (TBTO) in methanol at 60°C. Satisfactory penetration of the preservative and exchange of methanol and water occurred in a few hours. The methanol was removed rapidly from the wood by evaporation. Satisfactory penetration of TBTO into initially methanol-saturated samples occurred in a similar period. The factors influencing. such treatments are discussed. High initial moisture content of the wood and a high operating temperature are particularly desirable. Some aspects of the possible commercial operation of the process are discussed.
J A Petty


Low temperature drying conditions of Pinus radiata wood for avoiding internal stain
1989 - IRG/WP 3507
It has been observed that, if in little sawmills, timber is dried with a low temperature schedule, it arrives at destination with internal sapstain besides of superficial mould. In this study, the lowest drying temperature at which wood should be exposed for sterilization, which results to be 52°C, is searched. It is not possible to avoid entrainment of pentachlorophenol, even though a waiting period of 72 hours after dipping the wood in a pentachlorophenate/borax solution before drying is considered. The residual content of pentachlorophenol in wood should be at least 400 µg/cm² or the moisture content less than 23% for avoiding the development of mould.
M C Rose


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