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Testing method for the treatability of wood
1994 - IRG/WP 94-40031
In order to test and classify the treatability of wood species in pressure treatment processes with water-based solutions, a laboratory method was developed which allows the testing of small samples and limited sections of a stem, e.g. sapwood. The penetration of different liquids was determined separately concerning the three anatomical directions of wood. The common parameters for pressure impregnation were used on sap- and heartwood of eight indigenous and tropical wood species. An elastic epoxy resin proved feasible for coating the samples on five sides. From the data of the testing method a measure for the treatability was calculated, allowing to classify wood species into four treatability classes analogous to prEN 350-2 (1993).
A O Rapp, R-D Peek

Natural durability transfer from sawmill residues of white cypress (Callitris glaucophylla). - Part 3: Full penetration of the refractory sapwood of white cypress
2000 - IRG/WP 00-40167
The heartwood of white cypress, Callitris glaucophylla, is renowned for its termite resistance and durability against decay. The sapwood, which can represent up to 30% of log volume, is non-durable and refractory to conventional preservative treatment. Previous work ascribes the lack of permeability to oily deposits within tracheids and ray cells. Environmental scanning electron microscopy was used to investigate ultrastructural aspects of sapwood permeability. Several pre-treatment processes to improve permeability were tested with limited success. Solvent drying allowed preservative penetration but damaged the structure of the timber. Neither, long term water soaking nor an oscillating pressure/vacuum cycle had any effect on porosity to water-borne treatments. Through extensive modifications to a standard VPI process we can now repeatedly achieve full penetration with organic solvent-based wood preservative solutions into white cypress sapwood. Effects of this process on the strength of the timber are being evaluated. Work is continuing as to the most effective and efficient treatment schedule and the latest results will be presented at IRG 31.
M J Kennedy, L M Stephens, M A Powell

The use of pressure cycling to improve heartwood penetration in Pinus radiata (D. Don)
1995 - IRG/WP 95-40050
This study investigates the effect of cycling pressure on the treatability of radiata pine heartwood. The results indicate that liquid penetration into the heartwood is affected by the preconditioning method used and pressure treatment time. There is no significant improvement in the penetration of Pinus radiata (D. Don) heartwood when a cycling or pulsation process is used.
P R S Cobham, P Vinden

Non-pressure treatability of plywood by CCA, CCB and boron
2005 - IRG/WP 05-40295
Study on diffusibility and absorbability of CCA, CCB and boric acid in 3 mm thick 3-ply hardwood plywood at water saturated and air-dry conditions and dipped at same concentration (5%) and same duration of time (12 hours) revealed complete diffusion of all the preservatives at water saturated condition. Only the CCA-C was found absorbed by the plywood at air-dry condition. The rate of absorption and diffusion of CCA-C was found about 4.5 times higher than CCB and boric acid.
A K Lahiry

Treatability of plywood containing intermountain Douglas fir veneers
1982 - IRG/WP 3203
Eighteen sheets of plywood were obtained which contained intermountain Douglas-fir veneers from two regions of British Columbia. Following pressure treatment with chromated copper arsenate (CCA type C) and ammoniacal copper arsenate (ACA) the preservative penetration and retention in individual veneers was assessed. It was concluded from the study that the intermountain Douglas-fir veneer could not be adequately penetrated by either CCA or ACA, although the degree of penetration achieved with ACA was better than that recorded for CCA. The preservative retentions measured were generally in excess of that required for plywood to be used in the preserved wood foundation system.
J N R Ruddick, A Walsh

Untersuchungen über die Imprägnierbarkeit verschiedener türkischer Holzarten mit wirtschaftlicher Bedeutung
1976 - IRG/WP 370
Holzarten mit einer geringen natürlichen Dauerhaftigkeit können nur dann wirtschaftlich verwendet werden, wenn ihre Gebrauchsdauer durch einen zusätzlichen chemischen Schutz verlängert wird. Holzschutzmaßnahmen können nur regelmäßig geplant werden, wenn die Tränkbarkeit der verwendeten Holzarten bekannt ist. Aufgabe dieser Versuche war es daher, festzustellen, wieweit die Holzarten hinreichend getränkt werden können. In Rahmen der zur Zeit in der Türkei laufenden Entwicklungsvorhaben entstand die Frage nach den tränk-technischen Eigenschaften türkischer Holzarten, um ihre Verwendungsmöglichkeiten besser beurteilen zu können.
R Ilhan

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

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

An effective preservative treatment of borak bamboo (Bambusa balcoona Roxb.)
1996 - IRG/WP 96-40070
Adequate penetration and retention of CCA and CCB has been obtained in predried Borak Bamboo (Bambusa balcooa Roxb.), aboundantly grown in Bangladesh, with Full Cell Pressure Process. The treated bamboo can be used as building materials, the sufficient treatability ensured its long term best utilization at ground contact and indoors. Which will keep the environmental & socio economical conditions of Bangladesh more viable and normal.
A K Lahiry, S Begum, G N M Ilias, M A Matin Sheikh, M A B Fakir, M I Hossain

European standardization for wood preservation
1990 - IRG/WP 2359
G Castan

Effects of pretreatments for the amelioration of preservative impregnability using the Oscillating pressure method (OPM)
1995 - IRG/WP 95-40044
For the purpose of an amelioration of preservative impregnability, three types of pretreatment: the steaming, the explosion and the boiling, were tested. The specimens were prepared by the domestic four species: Itajii, Ryukyumatsu, Sugi and Hinoki, and 1 refractry imported species: Douglas-fir. The dimension of specimens was 20 x 20 x 300 mm³ and were treated with CCA in a laboratory OPM machine. Three OPM schedules and Bethel process without after vacuume were tested in this experiment. The results obtained were follows: 1. In the case of the treatment of green woods, the calculated retentions of preservatives based on those initial mass, were periodically slowly increased or sometimes decreased. This reason was considered the replacement of the free water in wood to the preservative solution. The sapwood of rather easy treatable species like Ryukyumatsu, was obtained good penetration by Bethel process. The sapwoods of treatable species like Sugi and Hinoki, were obtained best penetration by OPM-1 or by OPM-2. The combination of the steaming and the OPM was rather good results for all species tested of green woods. 2. In the case of the treatment of the air-dried woods, the combination of the steaming and the OPM was obtained rather good results for all species tested included the refractry specimens like Douglas-fir.
K Suzuki, I Asaoka, S Tani, K Okada, T Hidaka

Effect of fatty acid removal on treatability of Douglas-fir
1993 - IRG/WP 93-40008
Treatment of Douglas-fir with chromated-copper-arsenate (CCA) poses a major challenge. Several hypotheses based on the anatomical aspects as well as chemical reactivity of the preservative formulations with cell wall constituents and deposits have been proposed. Techniques to prevent pit aspiration or slow fixation reactions have, however, not significantly improved treatment. The presence of high molecular weight fatty acids have been reported to be responsible for higher hydrophobicity in some wood species. These acids can react with Cu+2/Cr+3 ions to form insoluble metallic soaps, thereby immobilizing Cu/Cr and increasing wood hydrophobicity by a mechanism similar to that employed in paper sizing. The effect of fatty acids on treatability was explored by removing these components via several extraction methods. In general, extracted wood had higher gross solution absorptions and chemical retentions, but preservative penetration was largely unaffected. The results suggest that removal or disruption of fatty acids can improve treatability of Douglas-fir heartwood.
S Kumar, J J Morrell

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

Study of the natural durability and impregnability of a metropolitan species of tree
1986 - IRG/WP 2261
The current and predictable evolution of construction timber supply conditions is motivating research for a more efficient utilization of native woods. It is now important to determine statistically reliable impregnability values on a national scale, and to evaluate the natural durability of woods recently introduced in France, or economically important native woods.
M E Mathieu

300 years water-logged wood: Treatability with CCA-C
1998 - IRG/WP 98-40103
The treatability of 300 years water-logged and recent wood (Abies bornmülleriana M.) was assessed by dip treatment and vacuum and pressure cycling with CCA-C. Treatment runs were evaluated on the basis of weight gain retention and radial and tangential penetration measurements. The preservative penetration and retention levels in the 300 years water-logged wood were higher than in the recent wood due to water-logging.
S N Kartal, N Yilgör

Innovations in the treatment of Southern pine heartwood
2000 - IRG/WP 00-40172
Whereas the sapwood of southern yellow pine (Pinus spp.) is readily treatable, the heartwood is essentially impermeable to preservatives such as chromated copper arsenate (CCA). Preliminary studies at the Mississippi Forest Products Laboratory indicate that increases in penetration and retention of preservative in pine heartwood can be obtained by subjecting kiln dried dimension stock to varying mechanical stresses using the patented TASK Process machine. The TASK Process machine incorporates varying levels of compression and/or vibration to mechanically stress lumber.
M G Sanders, T L Amburgey, H M Barnes

Methods of treatment of wood preservatives. The selection of appropriate preservation process with particular reference to mixed tropical forest resources. A key address
1982 - IRG/WP 3177
All wood is biodegradable. Many timber species have, however, sufficient natural durability to permit their use, particularly in protected situations, without any special precautions. Many others, of course, are readily attacked by insects and where there is sufficient moisture and air, by wood-decaying fungi. It is these timber species which benefit most from treatment with wood preservatives. Even the so called durables may also benefit so since all sapwood is perishable and durable heartwood in the sea or in ground contact eventually fails from attack by animals and/or micro-organisms. In recent years it has become apparent that for high hazard end uses it is necessary to consider the timber species/preservative type/treatment method as a single unit. It is of course possible, after accumulation of experience and test data, to group certain timber species into classes which can be processed together but until this has been established it is necessary to consider each and every timber species as a distinct biological entity which will respond differently to other timber species to preservative treatment. It has also been found that the most widespread treatment process, vacuum/pressure treatment, is inappropriate for many of the timber species available from the world's forests, particularly hardwoods. In ground contact, the commercially available preservatives do not provide the needed protection against fungal decay and in low hazard uses other preservatives and processes may be used more cost effectively for at least equally satisfactory results. In many temperate countries depletion of durable hardwoods led to wide use of perishable conifers in high hazard sites; wood preservation using tar oils or water-borne fixed preservatives applied by pressure improved these conifers so that in many uses they outlasted the best of the durable hardwoods. Thus, and rightly so, emphasis has been placed in most temperate countries on this approach, non-leachable preservatives applied by pressure to permeable coniferous wood. It is thus reasonable to assume that wood preservation has been very successful. Or has it? It depends on the approach made, and whether the objectives of those using wood preservation have been met. The selection of treatment methods depends heavily upon the objectives and the way successful wood preservation is gauged.
C R Levy

Study on the treatment of construction timbers by diffusion methods
1983 - IRG/WP 3252
Several species of timber that could be used for constructional purposes have to be pressure impregnated before such use. Pressure impregnation requires expensive equipment, and needs specialized trained operators, etc, which is not possible in most parts of India. Some timbers cannot be pressure impregnated, but can be treated by diffusion. Diffusion treatments could protect these timbers with simple inexpensive apparatus, using local resources and labour. It is our purpose, therefore, to locate such species which are commonly used in India for constructional purposes, and to preserve these by diffusion; to check if the results are satisfactory, and to find a preservative and simple procedure for the treatments of these timbers based on their treatability.
V R Sonti, B Chatterjee

Treatability of Siberian larch and spruce with chromated copper arsenate
1996 - IRG/WP 96-40060
Heartwood of Siberian larch (Larix gmelini) and spruce (Picea jezoensis) was pressure treated with chromated copper arsenate (CCA) Type B using a full cell process. Larch heartwood was somewhat difficult to treat than the spruce, although both species did not meet a minimum requirements of penetration and retention specified by the American Wood Preservers' Association (AWPA) for difficult to treat wood species in ground contact. To improve the preservative treatability of refractory larch and spruce, end matched heartwood lumber had been incised using either a conventional or a double density incising pattern, and then pressure treated with CCA Type B. The use of double density incising is necessary for spruce heartwood in order to acheive adequate treatment with CCA; however, the increase in incision densities and/or the use of high treating pressure may be required for adequate treatment of larch heartwood.
Gyu-Hyeok Kim, Woo-Gue Jee, Jae-Jin Kim

Some relationship between physical characteristics and treatability of Bolivian woods
1987 - IRG/WP 3434
Using the available data on physical characteristics of 25 Bolivian woods, some relationships between porosity, specific gravity and treatability (hot and cold open tank process with 5% pentachlorophenol) were analysed. The aim of this report is to give information on technical characteristics of Bolivian hardwoods which have been studied in this country by Centro de Desarrollo Forestal and in Peru by Junta del Acuerdo de Cartagena.
A S Viscarra

Treatability and retainability of two important bamboo species - borak and jawa of Bangladesh
2002 - IRG/WP 02-40248
Preservative treatment has been carried out with five different concentrations, i.e. 3%, 4%, 5%, 6% and 7% and durations, i.e. 2 days, 4 days, 6 days, 8 days and 10 days, at different moisture content, i.e. green and air-dry, and different direction of penetration, i.e. radial and both radial and cross-section for jawa and borak. It has been observed that retention of CCB is always higher in jawa bamboo than borak, which is a clear indication to consider jawa bamboo a more permeable and diffusible bamboo species for dipping process. Adequate retention of preservative for indoor use has been obtained in most of the cases. It has been observed that 6% concentration of preservative with 8 to 10 days duration of dipping provides the best results.
M N Islam, A K Lahiry, M O Hannan

Wood preservation in Thailand
1983 - IRG/WP 3265
The report gives a background to Thailand and its timber resources, production and consumption. The history of wood preservation in the country and its modern industrial development are described. Its 19 preservation plants are listed and the production figures of the two major ones given. The wood preservatives in use are noted and the costs of treating a railway sleeper in three different ways compared. The main hazards to Thai timbers, fungal damage, insect damage, and marine borers are detailed and 151 Thai timbers are listed with information on their natural durability and treatability. The organizations in Thailand concerned with the subject are outlined and the report ends by indicating that the future of wood preservation in the country is one of potential.
A Rananand, R Cockcroft

Evaluation of the fire retardant efficacy and leach resistance of an amino resin fire retardant - Preliminary report
1983 - IRG/WP 3260
The Early Fire Hazard Indices of untreated Pinus radiata were determined by testing to Australian Standard 1530, Part 3 - 1976. Differences in the performance of heartwood and sapwood were noted, with heartwood samples giving higher Ignitability, Heat Evolved and Spread of Flame indices. The treatability of Pinus radiata with Pyrogard H was assessed, and backsawn sapwood treated more effectively than all other combinations of direction of cut and sapwood/heartwood. Treatment of kiln dried DAR Pinus radiata with Pyrogard H did not produce dimensional changes of practical significance. This factor, plus a high concentration gradient of retardant in the treated timber, make it an ideal treatment for fully machined and profiled Pinus radiata. The leach resistance of the retardant was assessed. A greater percentage of phosphorus than nitrogen was leached, but the retardant remaining after leaching conferred similar protection to the unleached material at equivalent rententions. Pyrogard H is an effective leach resistant fire retardant for Pinus radiata.
W D Gardner, P N Alexiou, P Lind, D Butler

Untersuchungen über die Imprägnierbarkeit bei verschiedenen türkischer Holzarten von wirtschaftlicher Bedeutung
1976 - IRG/WP 365
Holzarten mit einer geringen natürlichen Dauerhaftigkeit können nur dann wirtschaftlich verwendet werden, wenn ihre Gebrauchsdauer durch einen zusätzlichen chemischen Schutz verlängert wird. Holzschutzmaßnahmen können nur regelmäßig geplant werden, wenn die Tränkbarkeit der gebrauchten Holzarten bekannt ist. Aufgaben dieser Versuche war es daher, festzustellen, wieweit die Holzarten hinreichend getränkt werden können. Im Rahmen der zur Zeit in der Türkei laufenden Entwicklungsvorhaben entstand die Frage nach den tränk-technischen Eigenschaften türkischer Holzarten, um ihre Verwendungsmöglichkeiten besser beurteilen zu können.
R Ilhan

Presteaming radiata pine heartwood to improve treatability
1983 - IRG/WP 3239
Steaming and holding before preservative treatment by the Bethell process greatly improved the treatment of radiata pine heartwood. Maximum penetration of preservative for the shortest holding period was obtained by the use of steam vacuum but the difference between this and steam venting was small when compared with the standard of treatment of air dried samples. A holding period of one day was sufficient to obtain virtually complete penetration of preservative during subsequent treatment of samples which had been steam vacuum seasoned. To obtain similar penetration in steam vented samples holding period would have had to be in excess of four days.
A J Bergervoet

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