Your search resulted in 82 documents. Displaying 25 entries per page.
Health aspects concerning the use of bifluorides in wood
1981 - IRG/WP 3173
An attempt has been made to find a correlation between the quantities F¯ and HF present among other ions in an 'Improsol' solution consisting of NH4F.HF and KF.HF, the quantity absorbed by the wood from this after immersion and the toxicological effects of this treated wood when it is used in rooms destined for the residence of people or animals or for the storage of foodstuffs.
H F M Nijman
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
Selective adsorption of antisapstain actives from two aqueous suspensions, and movement of actives into wood
1996 - IRG/WP 96-30103
Green-off-saw rough sawn Pinus elliottii (slash pine) boards were dipped in aqueous suspensions of two antisapstain formulations, NeXgenâ and Busanâ Sap Stain Preventative (Busan 1009), at three product concentration levels. Concentrations of active ingredients (NeXgen: CTL (chloro-thalonil) and MTC (methylene bisthiocyanate); Busan 1009: TCMTB (2(thiocyanomethylthio)-benzothiazole) and MTC) were monitored with respect to the amount of material dipped. Selective adsorption (removal of actives from the suspension at greater than simple volumetric transfer rates) varied with formulation and active ingredient, and increased with decreasing product concentration. Movement of active ingredients into dipped boards was monitored for 30 days after dipping. Mobility order was MTC >> TCMTB > CTL. Surface depletion characteristics were obtained for each active ingredient.
M J Kennedy, T L Woods
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.
Treatment behaviour of fresh and inservice catamaran logs
2001 - IRG/WP 01-30255
Catamaran is a conventional fishing craft fabricated by lashing 4 - 6 shaped logs of soft timber together. Over 73,000 of these craft fabricated out of 165,000 m3 of wood are in use along the vast east coast of India. Each craft lasts for 5-7 years. Over 15,000 m3 of timber is required annually for repairs and replacements of the craft. Such huge demand exerts enormous pressure on the resources. It is apt, therefore, to extend the practice of wood preservation to the catamaran sector and conserve the precious raw material. In order to achieve this objective, our Institute took up technology demonstrations way back in 1968. However, because of illiteracy and socio-economic constraints of the traditional fishermen, the efforts did not catch up well. Under these circumstances, as a renewed measure of propagation, treatment of 3 each of fresh as well as inservice catamarans was taken up some time ago. The results of pressure impregnation of these six catamarans made of Albizia falcataria timber with copper-chrome- arsenic (CCA) preservative were analyzed to understand the preservative absorption of the constituent logs. The study revealed that there was no significant variation in the total quantity of chemical absorbed among the fresh as well as inservice catamarans that served for three different periods prior to treatment . However, significant difference was noticed between all the fresh catamarans clubbed as one group and the inservice craft as another group. The CCA absorption ranged from 13.52 to 15.30 kg.m-3 averaging at 14.60 kg.m-3 in the fresh craft and 18.65 to 22.10 kg.m-3 averaging at 20.42 kg.m-3 in the inservice catamarans. Also, each constituent log of the six catamarans differed in its chemical content from the other. The analysis proved that it is possible to treat the inservice catamarans and achieve good preservative retentions.
V Kuppusamy, M V Rao, M Balaji, K S Rao
Creosoted radiata pine by non-pressure methods
1988 - IRG/WP 3486
Posts of Pinus radiata have been impregnated with creosote by immersion for 1, 3, and 7 days, and by hot-and-cold open tank with hot bath temperatures at 40°C and 60°C. On the basis of the retention rates obtained, suitable procedures are described for wood elements that are going to be in ground contact, and an analysis is made of the way in which the variables tested affect the results.
M V Baonza Merino, C De Arana Moncada
Steam conditioning of partially dried radiata and Corsican pine roundwood
1988 - IRG/WP 3499
The effect of partial air drying prior to steam conditioning and its effect on subsequent preservative treatment by the Bethell treatment process was investigated. A high standard of preservative treatment was obtained in both radiata and Corsican pine, irrespective of whether a period of partial drying was imposed before or after steam conditioning.
P Vinden, D R Page, K Nasheri
Reliability-based service life prediction methodology for assessment of water protection efficiency for coatings on wood
2003 - IRG/WP 03-20268
Assessment of water protection efficiency according to EN 927-5 has been shown to give significant differences in water absorption values for different types of coatings on wood. It is shown that the combination of EN 927-5 and an artificial weathering procedure gives more information regarding expected durability and long-term performance than a single measurement of water absorption on fresh, unweathered wood. A combination of water absorption measurement and artificial weathering could become a useful tool in product development as well as in benchmarking. Together with statistical tools, such as reliability-based service life prediction methodologies for prediction of the service life of coating systems a reduction in testing time may be achieved. The predicted service life can then be the input to integrated life cycle assessment of products for wood protection.
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
Fungal degradation of wood treated with metal-based preservatives. Part 2: Redox states of chromium
1996 - IRG/WP 96-10164
Concerns have arisen about the leaching of heavy metals from wood treated with metal-based preservatives, such as chromated copper arsenate (CCA). Of particular concern is the toxic redox state of chromium and arsenic in aging and decayed CCA-treated wood. Generally, hexavalent chromium is more toxic than trivalent chromium and trivalent arsenic is more toxic than pentavalent arsenic. The desired outcome from treating wood with CCA is total change of Cr(VI) to Cr(III) and As(III) to As(V). As part of an on-going study to determine the fate of copper, chromium and arsenic during aging and decay of CCA-treated wood, we detected Cr(III) and Cr(VI) in situ in CCA-treated southern yellow pine lumber. The redox states of Cr were determined using synchrotron X-ray fluorescence spectroscopy (SXRF). An SXRF microprobe was used to to detect Cr redox states by measuring X-ray absorption near-edge structure (XANES). The ratio of Cr(III) to Cr(VI) was determined (1) on the surface and interior of lumber two years after CCA treatment and (2) in lumber during decay by a CCA-tolerant fungus, Meruliporia incrassata TFFH-294. The XANES spectrum for Cr(VI) has a strong pre-edge feature that is not present in the spectrum for Cr(III). Only the Cr(III) XANES spectrum was detected on the surface and in the interior of the wood, indicating total reduction of Cr(VI). The XANES spectrum for Cr(III) was detected in wood after 12 week decay by Meruliporia incrassata TFFH-294, indicating that the fungus does not oxidize Cr(III) to Cr(VI) during the decay process. We are currently using XANES spectroscopy to detect and map in situ redox states of As in CCA-treated wood.
B Illman, S Bajt, T L Highley
Preservative absorption response of planks of Anogeissus acuminata for plank-built catamarans
2002 - IRG/WP 02-40245
Due to shortage of timber coupled with other compelling factors, traditional fishermen along the east coast of India, especially of Andhra Pradesh, of late, are departing from conventional log type wooden catamarans. Instead, they are fabricating catamarans out of timber planks of hard woods and utilizing thermocol for buoyancy. Mostly, locally available timber of a Combretaceae species, Anogeissus acuminata (Yon) is used to fabricate these plank-built catamarans. Since these catamarans are also built with untreated timber, there is every need to extend wood preservation technology to these craft also so as to achieve enhanced service life and conserve the resources. Therefore, the Institute of Wood Science and Technology took up treatment of timber meant for five such craft with copper-chrome-arsenic (CCA). Thirteen different logs were procured and converted into planks and batons of suitable sizes, debarked, cleaned and air dried under shade. While the length of the planks ranged from 0.81 to 6.53 m, the width varied from 16 to 44 cm. After sufficient seasoning, the material was pressure treated with 6% CCA by full cell method as per IS: 401 (1982). Chemical retentions were computed from the weight gained by the individual planks and sets of 20 batons immediately after treatment. The preservative absorption in the planks ranged from 13.05 to 69.80 kg/m3 averaging at 25.90 kg/m3 and that in the batons averaged at 32 kg/m3. The quantity of CCA absorbed by the planks was analyzed with reference to their length, width, thickness and volume. Planks when categorized to different length and volume groups exhibited clear difference in the intake of chemical by them but when categorized into different width and thickness classes showed not much variation. All the treated planks and batons after air drying in shade for 15 days were fabricated into five catamarans. Thus, though the planks of A. acuminata are either very long or very wide, they showed a positive response to CCA treatment by absorbing reasonably good quantities of preservative. Similarly, on fabrication of the catamarans, an average retention of 21.79 to 25.43 kg/m3 of CCA per craft could be achieved. These values fall into the recommended preservative absorption range of 16 to 32 kg/m3 (IS: 401, 1982) for marine structures.
V Kuppusamy, M V Rao, M Balaji, K Rao
Creosote immersion treatments in fence-posts of Castanea sativa, Pinus nigra and Pinus halepensis
1988 - IRG/WP 3488
The method of soaking in creosote was applied to fenceposts of Castanea sativa, Pinus nigra and Pinus halepensis, taking into account its easy use in the field. Absorption, retention and penetration rates were recorded and analysed. Absorption rates were higher in Pinus nigra than in Pinus halepensis, and lowest in Castanea sativa. Thin fence-posts always absorbed more preservative than thick ones. Penetration rates were similar in both pines, and much higher than in Castanea sativa. Retention levels were almost the same in Pinus nigra and Castanea sativa, and lower in Pinus halepensis.
C De Arana Moncada
A study of salt imbalances observed in recycled copper/chrome/arsenic preservative solutions in commercial practice
1987 - IRG/WP 3461
The study reported monitored tank solutions, sludge and other by-products using a standard CCA solution, when recycled. This recycling of the CCA solution is quite usual in between any commercial treatment schedules. Salt imbalances were observed and the possible reasons for such phenomena were studied. The paper discusses the procedure followed, the method of sampling the liquid after the charge and the analysis, to arrive finally at an aggregation and conclusion from the data.
V R Sonti, S Sonti, B Chatterjee
Absorption of inorganic salts solutions. Retentions of inorganic salts. Fire retardants
1990 - IRG/WP 3625
The study aims evaluated the impregnation capacity using fire retardants on woods with differents densities. At the same time, impregnation with several fire retardant salts were carried out in order to obtain their absortion and retention in wood.
A Garcia, J Navarro
TBTO absorption and penetration in pine joinery treated by various processes
1989 - IRG/WP 3523
Matched sections of several White pine (Pinus strobus) and Ponderosa pine (Pinus ponderosa) mouldings were treated with TBTO by Double vacuum, modified empty-cell, 15 second dip and several preheating treatments followed by a 15 s dip treatments. As expected the double vacuum and empty-cell (batch) treatments resulted in much greater retentions and penetrations than the dip treatments. The absorptions by the 15 s dip treatments could be improved significantly by preheating the wood to 60-90C° by microwave, radio-frequency or infra-red techniques. Since this approach is amenable to a continuous treatment process, it is being evaluated for potential commercial application.
P A Cooper, Y T Ung
Ancillary properties of vapor boron-treated composites
2001 - IRG/WP 01-40210
This paper discusses the water absorption, thickness swelling, and internal bond strength of North American composites treated using a vapor boron treatment process. For oriented strandboard, high boron loadings led to lower internal bond strength and lower thickness swelling. Water absorption results were variable but no deleterious effect of treatment was noted. For medium density fiberboard, the highest loadings led to reduced internal bond strength. Thickness swelling decreased with increasing boron level, but not significantly. As with OSB, water absorption results varied.
W A Jones, H M Barnes, R J Murphy
Heat treatment of wood strands for OSB production: Effect on the mechanical properties, water absorption and dimensional stability
2002 - IRG/WP 02-40238
The effect of heat treatment on the mechanical and physical properties of commercial OSB strands was evaluated. Heat treatment was applied under inert atmospheric conditions to wood strands. The aim of this study was to examine the heat treatment parameters to achieve significant reduction of thickness swelling (upon exposure to moisture in service) without causing excessive reductions in strength. Heat treatments of 200, 210, 220, 230, 240, 250, and 260°C for 20 minutes were applied and swelling tests were performed. Subsequently the modulus of rupture and modulus of elasticity were measured in wood strands. High temperature treatments resulted in significant reductions in thickness swelling of wood strands but resulted in 20% reductions of modulus of rupture and modulus of elasticity.
G J Goroyias, M D C Hale
Contribution of wood components on the absorption of copper amine
2000 - IRG/WP 00-30216
The contribution of wood components on the absorption of copper amine was investigated. Holocellulose, lignin and xylan absorbed significant amount of copper. The amount of copper absorbed by cellulose was almost negligible. The removal of extractive also decreased the amount of copper absorption. This study clearly indicates the importance of lignin, hemicellulose in the absorption of copper amine in wood.
D P Kamdem, Jun Zhang
Upright capillary absorption behavior of five important timbers and one bamboo species of Bangladesh
2004 - IRG/WP 04-40273
The upright or vertical capillary absorption rate of five different timber and bamboo species namely mango (Mangifera indica), kalajam (Syzygium cumini), kanthal (Artocarpus heterophyllus), sissoo (Dalbergia sissoo), mahagoni (Swietenia macrophylla) and mulibamboo (Melocana baccifera) were measured in relation to their specific gravity and duration of immersion. It has been observed that there was significant relation between increase of capillarity and timber species. From the analysis of data it was found that the rise of capillarity is more or less similar in case of bamboo, jam and kanthal but the values were comparatively lower than that of mahagoni, sissoo and mango. The value of the capillarity has been found the highest in mangowood. There was no significant relation with the rise of capillarity and advancement of time. Initially, the soaking rate of bamboo has increased at an increasing rate, but it soaks the solution at more or less same rate with time. It has been also observed that the absorption height has changed with the specific gravity of wood and absorption height has increased gradually with the increase of immersion time.
M A Islam, A K M A Bosunia, A K Saha, A K Lahiry
Influence of the peeling on the absorption in the sap displacement method
1990 - IRG/WP 3626
Results of tests on the Eucalyptus and pine fenceposts treated by sap displacement method are presented. Freshly cut post 2 m in length and 8 to 16 cm in diameter were placed for 6 days with their butt ends down in water soluble preservative solution (CCF) to a depth of about 65 cm, and these were inverted and kept in the same way for 3 days more. The treatment began a few hours after felling. The absorptions obtained in partially and totally barked fenceposts were compared. In both timber species, the barked fenceposts absorbed approximately two and a half times more preservative than the other fenceposts partially barked.
M V Baonza Merino
Preservative treatement of muli bamboo (Melocanna baccifera) by pressure process
2001 - IRG/WP 01-40194
This study was carried out in order to investigate the possibility of preservative treatment of split bamboo by pressure process. Whole bamboo is very difficult to treat by pressure process, which is the best and most dependable of all treating processes. Because it surface has a coat of impervious cutiular which make it very resistance to the penetration of liquid. Beside this it is prone to develop cracks under high pressure reducing strength to a greater extent. Split bamboo is used for different purposes. Generally muli bamboo (Melocanna baccifera) is used in splitting condition due to its strength and thickness. To find out the optimum schedule for the treatment of split bamboo, a number of schedule were carried out varying pressure and period. It was found that there was no significant variation with increasing pressure and period. It was observed that split bamboo can be satisfactorily treated by pressure process following a moderate treatment schedule with conventional water-borne preservatives.
K Akhter, M Younusuzzaman, M H Chowdhury
A Preliminary Report on the Properties of Engineered Wood Composite Panels Treated with Copper Naphthenate
2005 - IRG/WP 05-40294
This paper reports on our preliminary investigation of the properties of randomly oriented strandboard which had waterborne or powdered copper naphthenate (CuN) incorporated into the board during manufacture. When compared to zinc borate-treated controls (ZnB), the mechanical properties of strandboard (MOR, MOE, work-to-maximum load, internal bond strength) were not adversely affected by treatment with either form of copper naphthenate. In general, values for mechanical properties followed the trend untreated controls > waterborne CuN = powdered CuN > ZnB. Water absorption and dimensional properties followed a similar trend. This preliminary study suggests that CuN is a viable alternative treatment for engineered wood composites.
J W Kirkpatrick, H M Barnes
Moisture condition in treated wood exposed outdoors. A progress report
1989 - IRG/WP 3533
Wood treated with water-borne preservatives, mainly CCA (copper/chromium/arsenic), CCB (copper/chrome/boron) or CC (copper/chrome) is often said among users in Sweden to absorb more water than untreated wood. In laboratory tests this statement has not been confirmed but no field tests have been carried out in Sweden to study this phenomenon. In 1986 a project was started to compare water absorption during outdoor exposure between wood stakes of pine (Pinus sylvestris) and spruce (Picea abies) both untreated and treated with different preservatives. For comparison stakes of different species were included as well as painted pine stakes. Equilibrium moisture content in humid environment was tested for untreated pine-stakes and stakes treated with CCA and ammoniacal copper preservatives.
M-L Edlund, C E Sundman
Durability of surface preserved wood particle boards submitted to atmospherical influence
1995 - IRG/WP 95-40039
The worldwide problem of the continuously growing deficit of high quality natural wood material has caused the attempts of many research workers to find effective composites such as wood particle boards (WPBs) for replacing the massive wood for constructive purposes, depending on where the boards are exploited - in the open or under a shed, they are submitted to various climatic factors such as heating, drying, moistening, frosting, irradiation, that's why for reaching high atmospheric resistance, it is very important, a durable protection of the WPBs with suitable coatings against the atmospheric influence to be ensured.
Recent developments in the treatment of sawn spruce by double vacuum impregnation
1978 - IRG/WP 3114
The timbers used for building purposes in the U.K. and on the Continent of Europe are mainly softwoods. The two types of wood most used are redwood (Pinus sylvestris) and whitewood (Picea abies or Picea sitchensis). Other species are used to a lesser extent when considerations such as a long length requirement or width requirement demand the use of, for example, hemlock, Douglas fir or Parana pine. Traditionally redwood has been favoured in the U.K. for use as external joinery timber where the decay risk is high, and to date it is still used very extensively for this purpose. Whitewood on the other hand is used for carcassing and internal work. This pattern of usage is not reflected on the Continent and the rest of the world. This traditional situation may not continue to be with us indefinitely. In 1973, supply difficulties forced some U.K. external joinery manufacturers to use whitewood, and current timber production trends make a recurrence of this situation a likely probability. Already spruce is being used in laminated beams for swimming pool roofing and in flat roofs. In both situationa there is a high risk of fungal decay. It is with a view to this wider utilisation of whitewood that this paper is presented as a 'state-of-the-art' report.
C T Kyte, L D A Saunders