IRG Documents Database and Compendium

Search and Download IRG Documents:

Between and , sort by

Displaying your search results

Your search resulted in 198 documents. Displaying 25 entries per page.

Diffusion treatment plants (Latin America - Africa)
1974 - IRG/WP 333
B N Prasad

In-situ pressure injection for preservation of rubber wood (Hevea brasiliensis Muel Arg.)
1992 - IRG/WP 92-3688
Rubber wood is widely used for the manufacture of furniture, doors for housing and packing cases. However in an untreated condition it is highley susceptible to sapstain and decay fungi and borers. Its utility gets considerably reduced if the wood is not treated well in time. Preservative treatment has to be given within the period of felling and transport to prevent not only loss of structural properties and wood material. Although Boucherie, hot-cold bath diffusion, pressure impregnation, vacuum-pressure impregnation processes for treating timbers have been successfully employed for protection, but the process in cumbersome and difficult to adopt at the site of extraction. Hence, it was found necessary to evolve a simple and convenient method to treat trees in-Situ. A simple pressure injection technique was adopted to treat the standing tree using an instrument designed at the Institute (IWST). This instrument is easy to operate and inexpensive. It was observed that the movement of preservatives was satisfactory and effective. Samples of wood taken from treated stem of such trees were subjected to attack by brown and white rot fungi in the laboratory. It was observed that wood samples treated with Borax, boric acid and Bavistin (1:1:0.2); Borax, boric acid and Sodium pentachlorophenoxide (1:1.5:1) and Bavistin and Ekalux (0.5:0.5) showed higher resistance to fungi and insect attack compared to boric acid and Borax (1:1) in both laboratory and field conditions. Treated wood also retained natural colour and was free from fungal and insect attack for over 24 months in storage. Studies in this method of treatment of plantations species are in progress.
H S Ananthapadmanabha, V R Sivaramakrishnan

Steam/hold/APM boron treatment - Treatability trials with green gauged radiata pine
1987 - IRG/WP 3439
Freshly sawn 100 x 50 mm radiata pine was green gauged, steam conditioned and preservative treated with a mixture of borax and boric acid using a modified Alternating Pressure Method (APM) treatment schedule. A 12 hour holding period between steam conditioning and treatment resulted in the necessary moisture loss and moisture re-distribution to facilitate treatment to NZ Timber Preservation Authority preservative retention and distribution requirements.
P Vinden

Status of wood preservation industry in India
2005 - IRG/WP 05-30388
The paper traces the history of wood preservation industry in India, listing various mile stones for creation of treating capacity. The preservation industry developed with the development of rail road system on the line of most other developed countries. The most popular wood preservatives are CCA, CCB, ACC, Creosote and recently LOSP have also appeared in the market. The major users of CCA is the Cooling tower industry, which use more than 50% of the current CCA produced in the country. CCB and Boric acid :Borax rule the furniture industry. The use of LOSP is picking up as brush on applications and in the remedial treatments. The overall picture of preservative used (around 1350 tons CCA equivalent) is quite disappointing considering the volumes of non-durable woods used annually 22.5 million m3.
S Kumar

Removal of copper, chromium and arsenic from CCA treated wood using boron compounds
2005 - IRG/WP 05-50230
This study evaluates the copper (Cu), chromium (Cr) and arsenic (As) removal from CCA treated wood using boron compounds such as boric acid, borax (sodium tetraborate), and Timbor (DOT, disodium octaborate tetrahydrate) at varying (3 and 5%) concentrations. Remediation processes were taken at 1, 5 and 10 day intervals. Metals in remediated chips or sawdust were then analyzed using ICP and XRF. Results showed that, higher level of Cu was removed followed by As and Cr. The percentage removal of metals was higher in saw dust then chips. Borax at lower concentration (3%) removed 41.4%, 18.3% and 44.9% of Cu, Cr and As, respectively, in 10 days while at higher concentration (5%) 65.8%, 55% and 55.8% of Cu, Cr, As, respectively, were removed for the same period. Boric acid removed 39.7%, 15.5% and 35.6% at lower and 50.7%, 48.9% and 50.9% of Cu, Cr, and As at higher concentration, respectively, while DOT was not an effective extractant. Distilled water extraction removed 27.3%, 23.7% and 22.8% of Cu, Cr and As respectively. In case of chips, borax removed 30.3%, 19.7% and 24.9% of Cu, Cr, and As; boric acid removed 25.5%, 12.2% and 19.5%; DOT removed 22.8%, 10.8%, 14.2% and distilled water 17.7%, 11.1% and 10.2% of Cu, Cr, and As, respectively. Increasing the concentration of solution has greater effect on elements removal. Among the three compounds tested, borax removed higher levels of metals compared to boric acid and DOT.
B Tarakanadha, T Hata, S N Kartal, W J Hwang, Y Imamura

Preservative treatment of rubber wood (Hevea brasiliensis) to increase its service life
2005 - IRG/WP 05-40320
Rubber wood (Hevea brasiliensis) possess excellent properties for interior designing, wood working and furniture making. But it is very much susceptible to sap stain and mould fungi which decreases the service life. For profitable uses , it is necessary to increase the service life of rubber wood. To protect the rubber wood from wood degrading agents, the sawn timber were treated with Borax – boric acid solution and Copper-chrome -boron solution by soaking process and Lowry empty cell pressure process following moderate treatment schedule. It was found that rubber wood can be treated satisfactorily by both the processes with acceptable penetration and retention.
K Akhter

The efficacy of boron preparations
1987 - IRG/WP 3400
The toxicity threshold of boric acid for egg larvae of Hylotrupes bajulus Linné is approx. 0.4 kg/m³ of wood (71 g B/m³) over a 12-week test period, and approx. 0.3 kg/m³ of wood (53 g B/m³) over a 6-month test period. The corresponding values for borax are 0.5-0.6 kg/m³ of wood (56-68 g B/m³) and 0.3-0.4 kg/m³ of wood (34-45 g B/m³). The values are somewhat lower in the case of the egg larvae of Anobium punctatum Degeer. Boron compounds can only be used as stomach poisons. They have a very slow effect on the larvae of both the house longhorn beetle and the common furniture beetle. Boron compounds are very effective in preventive treatments, but less well suited to curative use. Boron compounds are particularly useful in the prevention of a wide range of woodrotting fungi. No fungus is known to offer serious resistance to boron. All of the fungi investigated are killed by the application of 632 g of boron per m³ of wood. Boric acid is more effective than borax against fungi because it contains a higher proportion of boron. True dry rot dies when 55 g of sodium polyborate is applied per m² of brick wall: this represents approx. 11 g of boron per m².
J T De Jonge

Diffusion treatment of gauged radiata pine timber using "Boracol 20"
1987 - IRG/WP 3437
Green gauged 100 x 50 mm radiata pine timber was preservative treated by brush application of "Boracol 20" followed by diffusion storage. Preservative retention analyses indicated that retention requirements in the core could be achieved within a six week diffusion period, thus representing a time saving of 25% over conventional boron treatment of rough-sawn radiata pine. Similar treatment of kiln dried radiata pine resulted in approximately 5 mm penetration. A longer diffusion period did not result in improved preservative penetration.
D R Page, P Vinden, S Retter

Water analysis in chemicals, wood or chemically treated wood using a new analytical method for selective water detection
2006 - IRG/WP 03-30391
Water or moisture content analysis can be a challenging task in many applications. However, knowing accurately the type of water which can be found in a given sample or product can provide important information about a chemical compound used for wood treatment and especially about the treated wood sample. Moisture content in wood plays an important role in fungal growth and it needs to be extensively monitored. In this study, a new method for the moisture content or trace water analysis will be reviewed. The principle of the method, the main components of the device, the advantages and disadvantages of the method called Selective Water Detection System (SWDE), will be reviewed and presented. Probe molecules and wood samples will be used to explain and examine the type of information one can get using this analytical method. The method can provide information about how water is bonded to a substrate and what type of interactions water has in a sample. This information can be used to evaluate the structure of a chemical used in wood preservation, monitor the water repellency, or determine the type of chemical compound present on the treated wood (e.g. hydration number, weakly or strongly bonded water molecules, etc.). Probe molecules based on boron, commonly used as wood preservative will be used to explain and describe the instrument capabilities and the type of scientific information which can be obtained.
R Craciun, D Taylor

Performance evaluation of Borax: Boric Acid treated Green bamboo through new VAC-FRI and conventional processes
2006 - IRG/WP 06-40327
Amongst giant arborescent grass bamboo is the only versatile member containing lignocellulosic materials like wood. Therefore it offers almost parallel uses where wood is traditionally an established material. The wood scarcity, environmental role of our natural forests, longer rotation cycle of plantation species, ban in felling, the ever growing utilization demands of wood to the tune of 3.2 million tones and its abundant use even as fuel and complex R&D technologies related problems like growth stresses, drying stresses, refractoriness in treatments are several interacting factors in the field of wood utilization. However, bamboo is a relatively simplified material in comparison to wood. Therefore, developmental work in bamboo processing is much easier and simpler in comparison to wood. The treatment of bamboo is much simpler than the treatment of wood in the form of poles provided appropriate technologies are developed. Bamboo species are perishable regardless of prevailing beliefs, regarding its durability amongst traditional societies. More so one rainy season any where in the country or round the year high humidity zones in costal areas and Northeast are suitable grounds of severe sapstains or borer attacks in its products in case adequate treatments are not done. The present paper highlights this aspect and describes the developmental work at FRI. Boucherie process of treating green bamboo is well known. Further progressive work was done at FRI and a number of processes were developed for treating bamboo in green/dry, split and round form. However the latest breakthrough is achieved in treatment of bamboo and this new approach is much faster and more efficient while maintaining the economics of the treatment well within the reach to entrepreneurs one such a process VAC-FRI. D. strictus, B. nutans, B. arundinacea, B. balcooa and B. gigantius, species, known for structural and other uses were treated with 4% Borax: Boric acid by Boucherie, VAC-FRI, wick and diffusion processes. Natural durability and performance after treatment was evaluated under shade and ground contact. Results revealed that new process VAC-FRI is comparable to all other known conventional process.
S Tripathi, S N Nautiyal

Preservative treatment of strips of Bambusa balcooa by soaking process using Borax-Boric acid
2008 - IRG/WP 08-30478
Bamboo strips made from Borak bamboo (Bambusa balcooa) were treated with 10% borax-boric acid aqueous solution by soaking process. The moisture contents of the bamboo strips were 12%, 20% and 30%. The strips were soaked for one, two, three, four and five days. The penetration of the solution was investigated by colour test after soaking and drying. Full penetration was observed after three days of soaking in case of strips containing 12% and 20% M.C and the strips containing 30% M.C showed scattered penetration after five days. The retention of the preservative chemicals through the strips was calculated from the absorbed solution after treatment. Retention of 25.5 kg/m3 and 21.5 Kg/m3 was found through the strips of 12% and 20% M.C respectively after three days. The strips containing 30% M.C attained 20.5 Kg/m3 retention after five days. The strips containing 12% and 20% M.C were used for making composite products for the preparation of chair and table and kept for service test.
K Akhter, M W Sheikh, M M Rahman, T A Chowdhury, M H Chowdhury

Effect of borax-boric acid Treatment of simul (Bombax ceiba) Veneers on Glue-Bond Quality of Plywood
2010 - IRG/WP 10-40525
The glue-bond quality of plywood made of treated simul (Bombax ceiba) veneers was investigated. The veneers were treated with cold and hot water solution of borax-boric acid (BB) of different concentrations and treatment durations. The plywoods were made at three different pressures in hot press using urea formaldehyde glue. The glue-bond strength of untreated plywood in dry shear-test was found to be 2.17 and 2.29 N/mm2 made at 1.05 and 1.40 N/mm2 pressure respectively. It was observed that the values of load at failure of treated plywood in dry shear-test gradually decreased with the increasing treatment duration and concentration of solution. Comparison of the bond strength of untreated plywood with the treated ones made with urea formaldehyde glue showed that all the treatment combinations lowered the bond quality. It was also found that 10% BB solution and highest treatment duration (3 for cold water days and 60 minutes for hot water) lowered the bond strength of the plywood which met ‘B-grading’ requirement. However, the values of glue bond strength in all other BB treated plywood met ‘A-grading’ requirement for gluing. It may be due to the highest percentage of chemical deposition within the cell wall structure lowered the bond quality. For all the treatments, low values of shear strength were observed in plywood made of hot water-treated veneer compared to that of cold water.
K Akhter, Md Abul Hashem, S Akhter

Preservative Treatment of simul (Bombax ceiba) Veneers with Hot and Cold Water Solution of borax-boric acid by Soaking Process
2010 - IRG/WP 10-40528
Veneers of simul (Bombax ceiba) were treated with different concentrations of water- borne preservatives borax-boric acid (BB) by soaking process for different time periods. In the case of hot water treatment, it was found that the average retention of preservative chemicals increased gradually with the increasing treatment period from 20 minutes to 60 minutes. Similar trend was observed in the case of cold water treatment when treatment period was increased from 1 day to 3 days. The maximum retention (20.37 kg/m3) was observed from the samples treated with 10% BB solution for 60 minutes and in 2.5% BB treated samples, the average retention gradually increased from 5.35 kg/m3 to 7.16 kg/m3 when treatment duration was varied from 20 to 60 minutes. In the case of cold water treatment, maximum retention (22.97kg/m3) was observed from the veneers treated with 10% BB solution for 3 days and 7.35 kg/m3 retention was obtained when treated with 2.5% Borax-boric acid solution for 1 day. According to the Indian Standard (IS-1902), the retention of 4 kg/m3 boron compounds are sufficient to offer protection for non-structural purposes.
K Akhter, Md Abul Hashem, S Akhter

Effect of preservative treatment on dimensional stability of plywood made of treated simul (Bombax ceiba) veneer
2012 - IRG/WP 12-40575
The dimensional stability such as thickness swelling and water absorption of plywood made of treated simul (Bombax ceiba) veneers were investigated after 2 hours and 24 hours soaking under water. The veneers were treated with hot water and cold water solution of borax-boric acid (1:1), neem leaves and mahogany seeds of different concentration (1:10, 1:20, and 1:40) at different treatment duration. It was observed that the values of swelling were increased with the increase of soaking time from 2 hours to 24 hours. In the case of plywood made of borax-boric acid treated veneers, the percentage of swelling were increased with the increase of borax-boric acid concentration. The values of thickness swelling were also increased with the increase of treatment duration from 20 minutes to 60 minutes and 1 to 3 days. The values of swelling obtained in plywood made of neem leaves and mahogany seeds treated veneers were higher than that of borax-boric acid treated veneers and near to the untreated samples. The mean values of percentage of water absorption in plywood after 2hrs and 24 hours water soaking were determined. It was found that after 24 hours soaking, plywood made of mahogany seeds treated veneers absorbed more water than that of neem leaves treated veneers. All the values obtained from treated samples after 2 hours and 24 hours soaking were lower than the control samples. But it was observed that higher amount of water was absorbed in neem leaves and mahogany seeds treated board in comparison with borax-boric acid treated board. It was also noted that the values of water absorption in leaves and seeds treated board were near the values of untreated samples.
K Akhter, M Mahabubur Rahaman, A Ara

Development of composite furniture using bamboo strips, bamboo mat and rubber wood veneer
2014 - IRG/WP 14-40679
Bamboo offers cost-effective component in panel form is well suited to wood substitute can be used as furniture components. In the present study, borak (Bambusa balcooa ) bamboo were used for manufacturing bamboo panel. Mitinga (B. tulda) bamboo were used for making mat and rubber wood veneers were used for manufacturing mat overlaid veneer board. Borax-boric acid (BB) treatments were given to enhance the durability of mat, strips and veneer. The treatments were carried out using borax-boric acid (1:1) aqueous solution of different concentrations at different time schedule by soaking process. The optimum retention of preservative chemicals through mat, strips and veneer were determined. Using 5% BB solution, the average retention was found 21.90 kg/m3 in A (1.22 m X 0.91m) size mat and 24.39 kg/m3 in the B (0.61 m X 0.91m) size mat after 3 days soaking. Using 7% solution, retention of 25.17 kg/m3 A size mat and 28.44 kg/m3 were obtained in B size mat after 3 days treatment. In the case of bamboo strips, highest retention of 26.22 Kg/m3 was found when treated with 7% solution for 3 days. Highest retention 24.53 kg/m3 was obtained in 7% BB treated rubber wood veneers after 3 days soaking. Average retention of 22.07 kg/m3 was found when veneers were treated with 5% BB solution for 3 days. It was observed that, veneers were treated with 7% BB solution attained average retention of 19.20 to 24.53 kg/m3 after 1 to 3 days treatment. It was found that the retention were gradually increased with increasing concentration and time period. After preservative treatment, the materials were used in making composite products for chair.
K Akhter, M Mahabubur Rahaman, M H Chowdhury, M Zahirul Alam

Incorporation of raw boron minerals to protect particleboard against decay and mold fungi, termites and insects
2016 - IRG/WP 16-40729
This paper evaluated the biological performance of particleboards incorporated with the raw boron minerals ulexite and colemanite against decay, mold fungi, termites and insect larvae in comparison with that of particleboards with zinc borate, or boric acid plus a borax mixture. The results showed that ulexite and colemanite were highly effective against the decay fungi and termite attack in laboratory conditions. However, the boron minerals tested were not as effective as zinc borate or the boric acid/borax mixture in preventing mold growth. In general, the boric acid/borax mixture combination was more effective against Anobium larvae than the other compounds. Less boron release was seen in the specimens containing zinc borate and colemanite than in those containing ulexite or the boric acid/borax mixture. Further mechanical and physical tests (water absorption, swelling etc.) will be needed to evaluate the particleboard properties and the compatibility of the boron minerals with glue and manufacturing conditions.
S N Kartal, E Terzi, P Gerardin, C M Ibanez, T Yoshimura

Five-year evaluation of a field trial of Eucalyptus grandis poles treated with zinc and boron
2017 - IRG/WP 17-30721
Round Eucalyptus wood treatment in sequential stages with inorganic borates and metal salts (zinc sulfate and boric acid+borax) was studied; the aims were to form an insoluble precipitate of zinc borate inside wood and to reduce treatment costs by performing the first treatment by simple ascent and diffusion of the preservative, at the same time as it was sought to impregnate the heartwood. The second preservative was applied by pressure and non-pressure methods, and the effectiveness and retention achieved were compared. This paper presents the results of treatments effectiveness after five years of field trial. The degree of deterioration was rated for different treatments and the deterioration index was added. It was determined the average life time of the test pieces. B and Zn remaining in wood after 5 years were quantified in the aerial and buried parts of test pieces The determinations of Zn and B in a sample taken from the aerial part and another near the ground line of the test specimens with equal treatment, yield the same results in both points. The concentration of zinc could be determined in no case, because it is less than 1 μg / ml, boron could be determined, which indicates a longer permanence in the wood even in those specimens without second treatment. Untreated controls had a deterioration index (DI) of 100 after five years, while the treatment with best performance had a DI of 25. The highest deterioration rates are observed in the wood subjected to simple ascent of any of the salts (boron or zinc). At the same time treatments that begin with simple ascent of boron show a superior performance compared to those that use zinc salts, whereas the one which applies Zn in the second treatment by the Bethell method, shows the greater durability. The treatment in stages of Eucalyptus grandis round wood, shows greater effectiveness when the first stage applies boron salts and the second salts of zinc by Bethell's method. Zinc borate may be formed in situ under the treatment conditions.
C Ibáñez, A Camargo, C Mantero, M Rabinovich

Effects of Borax and Boric Acid as Fire Retardants on the Resistance of Pterygota macrocarpa Wood to Fire Tests
2022 - IRG/WP 22-30770
The combustible nature of wood as a building material, when exposed to hazards of fire underscores the reason for fire retardant treatments. Pterygota macrocarpa wood is commonly used by builders in Nigeria for roof and other structural applications. Therefore, this study was carried out to assess the effect of Borax and Boric acid on the fire-retardant properties of P. macrocarpa wood. Wood samples of dimension 200 x 95 x 10 mm were obtained from the harvested tree of P. macrocarpa across and along at 25%, 50% and 75% of the total length. The result revealed that the control samples without any fire retardant treatment had the highest weight loss of 16.06±7.61 %, followed by samples treated with boric acid (14.74%), while the lowest percentage weight loss of 4.26±1.51 % was observed for P. macrocarpa wood treated with borax. The study shows that percentage weight loss due to combustion of borate-treated wood samples decreases with an increasing proportion of borax in the treatment combination revealing that borax provides better protection than boric acid.
J M Owoyemi, O Apogbona, T O Akinwamide

Synergistic effect of boron on Streptomyces rimosus metabolites in preventing conidial germination of sapstain and mold fungi
1992 - IRG/WP 92-1565
We evaluated the synergistic effect of boron (4% BAE solution of Tim-Bor or 4% boric acid) on Streptomyces rimosus metabolites in preventing spore germination of sapstain and mold fungi using plate bioassay, Southern yellow pine and sweetgum block tests, and green pine log sections: sapstain -- Ceratocystis coerulescens, Ceratocystis minor, and Aureobasidum pullulans; mold fungi -- Aspergillus niger, Penicillium spp, and Trichoderma spp. Inhibition of spore germination in plate bioassay by metabolites with boron was more effective than without added boron. Treatment of wood samples with the mixture of boron and unconcentrated metabolites also resulted in the synergistic effect and completely inhibited spore germination of sapstain and mold fungi.
S C Croan, T L Highley

Response of the Formosan Subterranean Termite (Coptotermes formosanus) to Cellulose Insulation Treated with Boric Acid in Choice and No-Choice Tests.
2004 - IRG/WP 04-10532
The tunneling ability of the Formosan subterranean termite Coptotermes formosanus Shiraki through a cellulose insulation material containing11.1% boric acid was tested in choice and no-choice bioassays. We examined tunneling behavior and mortality of termites exposed to treated and untreated insulation material in miniature simulated wall voids. In a choice test termites tunneled through untreated insulation in all but one of the replicates used. Termites were unable to fully penetrate any of the replicates containing treated insulation and experienced a significantly higher mortality (78.4 ± 18.4%) than termites exposed to untreated insulation (11.6 ± 5.6%, F = 60.4, df = 1, P < 0.0001). In a no- choice test termites fully penetrated all replicates containing untreated insulation and experienced 37.1 ± 37.2% mortality. Termites exposed to treated insulation in this test experienced a significantly higher mortality of 100.0% (F = 14.3, df = 1, P < 0.005), and did not fully penetrate the treated insulation.
M E Mankowski, J K Grace

Boron treatments for the preservation of wood - A review of efficacy data for fungi and termites
1994 - IRG/WP 94-30037
Boron treatments have been used for many decades for protection of timber from biological attack and also as a fire retardant treatment. In recent years there has been an increased interest in boron treatments as an option for protection of structural timbers&apos; e.g. timber framing used in termite risk areas. This paper reviews efficacy data for both fungi and termites relevant to this end-use.
J A Drysdale

Preliminary results of investigations on screening test of chemical compounds suitable for the preservation of lignocellulosic materials against biodeterioration
1976 - IRG/WP 262
This paper investigates the possibilities of reducing the time needed for the determination of the effectiveness of chemical compounds from the point of view of their eventual application to lignocellulosic materials for preservation against decay and soft-rot.
K Lutomski, S S Neyman

Comparative investigations on the influence of wood seasoning, wood properties and temperature on the toxic values of wood preservatives against Hylotrupes egg larvae
1970 - IRG/WP 28
Comparative tests carried out at three institutes indicated the influence of kiln temperature, position of wood specimens in the cross sectional area and test temperature on the toxic values determined in accordance with DIN 52165 with egg larvae of the house longhorn beetle (Hylotrupes bajulus L.). The preservatives applied were boric acid in distilled water and g-benzene-hexachloride dissolved in chloroform; the timber species used was pine sapwood, (Pinus sylvestris L.). The method of seasoning had no influence on the toxic values of boric acid. With the g-BHC, however, the toxic values gradually increased with rising kiln temperatures (20°C, 70°C, 105°C). With boric acid the position of the sapwood samples in the log had no influence on the toxic efficacy; with g-BHC the efficacy was slightly greater in the outer sapwood, compared with the inner sapwood. The test temperatures (20°C, 24°C, 28°C) yielded different toxicity results for boric acid. At 24°C and 28°C the threshold values were somewhat below those of 20°C; they agreed with the values obtained at 20°C after a longer test period. With g-BHC different temperatures did not affect the results. An explanation is suggested for the causes of the influence exerted by the kiln temperature and wood properties on the toxic values of g-BHC. There was good agreement between the toxic values obtained in the different institutes.
G Becker, T Hof, O Wälchli

Options for accelerated boron treatment: A practical review of alternatives
1985 - IRG/WP 3329
Boron wood preservatives are almost exclusively applied by momentary immersion and block diffusion storage. Alternative techniques are described which can be used to accelerate boron treatment. Diffusion coefficients have been derived to define the acceleration of diffusion with increasing temperature. Schedules are described for pressure impregnation of green timber, involving steam conditioning, evacuation and alternating pressure method treatment. Timber Preservation Authority penetration and retention requirements can be met in approximately 4-5 h. The optimum schedule, however, included a 12 hour holding period between steaming and preservative treatment. A method of applying boron preservatives as a vapour is described, Trimethyl borate vapour reacts with wood moisture to form boric acid. The kinetics of this reaction, however, are very fast. This limits treatment to timber dried to very low wood moisture contents.
P Vinden, T Fenton, K Nasheri

Movement of boron from fused boron rods implanted in Southern pine, Douglas fir, red oak, and white oak timbers
1995 - IRG/WP 95-30061
This paper reports the distribution of boron from fused boron rods installed into six-inch (15.2 cm) square timbers of Douglas-fir, Southern Pine, red oak and white oak exposed aboveground. The composition and size of rods was: sodium borate and sodium borate-copper oxide (8.5 x 100 mm²); sodium borate-copper, sodium borate and boric oxide-copper oxide (12 x 76 mm²). The boric acid equivalent was roughly monitored by the curcumin/salicylic acid color test and the presence of copper was detected by the chrome azurol-S reagent. One year after installation of rods, movement of boron was determined by application of curcumin dye to increment cores removed at various distances from the site of boron rod installation. A portion of a sodium borate treated Southern Pine timber was also analyzed by spraying curcumin dye on sawed longitudinal and transverse sections. At 2 years, one foot sections were removed from all timber species, sawed as above, and boron and copper detection reagent sprayed on the sawed surfaces. Movement of copper from rods in all timbers was virtually nil. Both transverse and longitudinal movement of boron from rods was greatest in Southern pine which also had the highest moisture content. Movement of boron was next best in red oak. There was little movement of boron away from the rods in white oak and Douglas-fir.
T L Highley, L Ferge

Next Page