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The biostatic effect of copper on decay of fire retardant-treated mining timber
1991 - IRG/WP 1507
Blocks of Eucalyptus grandis were treated with 20kg/m³ ammonium sulphate as fire retardant and challenged with Coriolus versicolor. Replicates were soil buried. A second set of blocks was treated with retardant and copper at 6.6 kg/m³ (ie 1% w/w), and challenged similarly. After 8 weeks weight losses produced by Coriolus versicolor in untreated, retardant treated and copper supplemented blocks were 45, 25, and 0% respectively, and corresponding weight losses in soil were 27, 25 and 10%. These results, and electronmicroscopical observations, showed conclusively that Eucalyptus grandis treated with fire retardant was rapidly decayed, and that copper inhibited such decay.
G D Shelver, E A Shelver, A A W Baecker


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


Bibliography: Interactions of wood preservatives with wood, metals, glues, paints and concretes
1983 - IRG/WP 3271
H Becker


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


Distribution of fire retardant chemicals in kempas (Koompassia malaccensis)
1994 - IRG/WP 94-40037
Samples of Kempas (Koompassia malaccensis) heartwood were treated by vacuumpressure impregnation with solutions of monammonium phosphate, diammonium phosphate, ammonium sulphate or a borax-boric acid mixture. A commercial saltbased fire retardant formulation was also used. After slow air drying, the treated wood samples were sub-divided and zonal analysis carried out in order to determine the gradients of chemical retention form surface to core. Steep gradients of fire retardant chemicals were found irrespective of formulation. In a pyrolysis study, the amount of residue after pyrolysis at 550°C was proportional to the retention gradients of the fire retardant chemicals being greatest in the surface zones and least in the core of the samples.
A R A Malek, R J Murphy


Bibliography on the use of boron compounds for the preservation of wood
1973 - IRG/WP 315
This bibliography is based on an earlier literature survey prepared by J. Thornton and Wm. E. Bruce (O.E.C.D. Document No. 27/DAS/CSI/M/91) which was enlarged and revised for a meeting in Paris in October 1968 (Document 27/DAS/CSI/M554) by Professor W. Bavendamm of Reinbek. The latter (1968) document with its 166 references has now been extended and brought up to date. Acknowledgments are due to Borax Consolidated Ltd. and to the New Zealand Forest Research Institute who have both helped by providing us with further compilations of their own. Boron compounds have been in use in the past and are still found useful in medicine in the form of boric acid solutions and boracic ointment. They have also been used for the conservation of foodstuffs. In the treatment of wood they were first mostly used as fire retardants. Since the Second World War they have become increasingly important in the field of wood preservation.
R Cockcroft, J F Levy


Effect of fire retardants (monoammonium phosphate and diammonium phosphate, mixture of monoammonium phosphate and borax and ammonium sulphate) on beech wood with dipping and Lowry methods
2006 - IRG/WP 06-40350
In this study, the possibilities of using four kinds of chemicals as fire retardants with 12% concentration for beechwood (Fagus orientalis Lipsky) was surveyed. Providing testing samples that are related to the measurement of fire resistance properties according to JIS A-1321-1975 standard were evaluated. Wood samples were impregnated with Lowry and dipping methods. In this study, samples impregnated with diammonium phosphate by Lowry method had the best fire resistance properties. Wood samples impregnated with diammonium phosphate had the highest compression parallel to grain and highest resistance of hardness and samples impregnated by ammonium sulphate had the least total shrinking.
M Akhtari, D Parsapajouh, M Arefkhani


Effect of fire retardants (monoammonium phosphate and diammonium phosphate, mixture of monoammonium phosphate and borax and ammonium sulphate) on beech wood with dipping and Lowry methods
2006 - IRG/WP 06-40350
In this study, the possibilities of using four kinds of chemicals as fire retardants with 12% concentration for beechwood (Fagus orientalis Lipsky) was surveyed. Providing testing samples that are related to the measurement of fire resistance properties according to JIS A-1321-1975 standard were evaluated. Wood samples were impregnated with Lowry and dipping methods. In this study, samples impregnated with diammonium phosphate by Lowry method had the best fire resistance properties. Wood samples impregnated with diammonium phosphate had the highest compression parallel to grain and highest resistance of hardness and samples impregnated by ammonium sulphate had the least total shrinking.
M Akhtari, D Parsapajouh, M Arefkhani


Surface color and roughness characteristics of medium density fiberboard (MDF) panels treated with fire retardants
2008 - IRG/WP 08-40420
The objective of this study was to determine surface characteristics and color change properties of Medium Density Fiberboard (MDF) treated by fire retardants (FR) with 10% concentration. Experimental panels were made using by melamine ureaformaldehyde (MUF) adhesive having 10%, 15%, 20% of melamine. The surface properties of the samples were determined using a fine stylus technique. Three roughness parameters, namely average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Rmax) were determined from the surface of the samples. Color change properties of MDF samples were evaluated to CIE L*a*b* methods by a spectrophotometer (Minolta CM-2600d). It was found that the surface roughness values of the FR treated MDF panels were higher than those of control panels. The highest surface roughness values obtained from MDF panels treated with MAF+BA+NPB, MAF+BA+BX, the lowest values obtained from MDF panels treated with MAF+AL. Also surface roughness of the MDF panels improved with increasing melamine additive rate in the MUF adhesive. According to CIEL*a*b method, color change properties of the samples showed variation as function of chemicals type. Especially, while the highest color change(?E) were determined for MDF samples treated with MINPB and MAF+BA+NPB, the lowest color change (?E) were obtained from MDF samples treated with MAF+AL, MIN.
D Ustaömer, M Usta, S Hiziroglu


Laboratory and field exposures of FRT plywood: Part 1. Physical test data
2008 - IRG/WP 08-40426
Our understanding of the laboratory induced degradation with fire retardant systems is currently limited since we are unable to correlate laboratory steady-state experiments with actual in-service field degradation. Current model studies have generally been limited to isothermal rate studies with selected model FR chemicals. Other factors also play a major role in the degradation of FR-treated wood. These factors, which have not been studied in any detail, include relative humidity/moisture content cycles and thermally-induced evolution of ammonia from ammonium phosphates to give phosphoric acid. The objective of this study was to determine the relationship between laboratory and field results based on strength-temperature-relative humidity (moisture content)-FR chemical interactions. The impact of the variables was evaluated by measuring bending strength properties and comparing matched laboratory and field exposure samples. In this first paper, the physical test data show the positive effects of adding a buffering system to model FR compounds when exposed to high moisture environments and the negative effects of increasing the moisture in the in-service environment during exposure.
H M Barnes, J E Winandy, C R McIntyre


Experimental Measurements of Fire Retardants on Plywood at Fire Test
2015 - IRG/WP 15-40709
The use and development of wood composite materials increased in the past few years. However, in Brazil there are some restrictions on these products regarding their use, since it could be considered a potential risk at a fire situation. Thus, becomes evident the need for researches aiming to fit these in safety standards. This study aims to evaluate the efficiency of two new fire retardant products produced by a Brazilian industry. Tests were performed in plywood panels of Pinus spp previously immersed, varying the products concentrations and compared with untreated samples. The test used to evaluate the flame spread in a panel was the modified Schlyter test. The product in question was proved efficient, before and after shutting off the burner. Comparing with the panels without treatment, there was a decrease of 400% of the height of the flame spread on the treated ones.
G C A Martins, L A Marcolin, J M Vidal, C Calil Jr


Fire retardant treated wood products – Properties and uses
2016 - IRG/WP 16-30701
Wood is combustible, but can still perform very well in fire, especially for load bearing structures. However, visible wood surface may not fulfil the fire requirements in building codes and fire retardant treatments may be an option. The highest reaction to fire classification for combustible products may then be reached. However, the excellent fire performance of the virgin fire retardant treated, FRT, wood products may degrade over time, especially in outdoor applications. Two cases of long term durability of FRT wood products exist and standard procedures are available for limited hygroscopicity and maintained fire performance after weathering. Structural degradation may also occur, but is relevant only for load-bearing uses. Recommendations on end uses and suggestions for further research are included.
B Östman, L Tsantaridis


Selection of heat flux value for wood fire retardants testing using MLC
2018 - IRG/WP 18-40846
One of more crucial elements of investigating treated wood combustion properties with the use of a cone calorimeter is a proper selection of heat flux (HF). The HF level is directly reflected in time to ignition and a thermal degradation degree. The ignition of raw wood or of wood ineffectively protected against fire occurs at a low HF level, i.e. 10-20 kW/m2. By contrast, the ignition of wood which is effectively protected against fire, may occur no sooner than at HF 50 or even at 75 kW/m2. The aim of the paper was to analyse the problem of the selection of heat flux intensity in both experimental and standard fire testing with the use of a mass loss calorimeter (MLC). The subject of the analysis was wood treated with protective agents of various durability and fire resistance. On the one hand, the high HF value for wood samples of low fire resistance restricts or even excludes practical applications of an MLC as a tool for the evaluation of fire protection efficiency. On the other hand, too low value of HF prevents wood either from ignition or from determination of its thermal degradation degree. It especially applies to the situation when wood is effectively protected against fire. In both cases, the problem arises at the interpretation stage of obtained results. The identified problem was presented on the example of wood treated with chemical compounds which are ingredients of commonly used fire retardants, i.e. MAP – monoammonium phosphate, DAP – diammonium phosphate and PC – potassium carbonate, well known for their fire retardant properties. They are also known for their high solubility, which proves their high leaching from wood resulting consequently in a significant decrease in fire retardant properties. Unfortunately a versatile research procedure was not proposed in the performed study. However, the necessity for the individual selection of physical properties of a combustion process was emphasised. The above forces an unconventional method of result interpretation.
B Mazela, W Perdoch, W Grześkowiak, A Batista


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


Fire resistance of preservative treated fence posts
1994 - IRG/WP 94-30033
Pine fence posts were pressure treated separately with CCA-C, CCA-wax, CCA-oil and creosote. Treated posts and untreated controls were planted in the ground in a randomised block design, weathered for six months and then subjected to a controlled burning test using two fuel loads. Creosote treatment increased the time that posts were alight whereas CCA treatment had no such effect. However, CCA treated posts smouldered until destruction of the majority of the posts occurred. Posts treated with CCA-oil took longer for destruction to occur than posts treated with CCA-C or CCA-wax. Creosote treated posts and untreated controls did not show prolonged smouldering and consequently were not destroyed by the burning test, although their strength was reduced. A high fuel load increased the time that posts were alight and smouldering, and for CCA treated posts decreased their time to destruction.
P D Evans, P J Beutel, C F Donnelly, R B Cunningham


Fire resistance of Alder wood treated with some chemicals. Part II. Effect of Other Chemicals on the Combustion Properties
2002 - IRG/WP 02-40235
Samples from alder wood (Alnus glutinosa (L.) Gaertn. subsp. barbata (C.A.Mey) Yalt.) were impregnated according to ASTM D 1413-88 with boron compounds (boric acid, borax, sodium perborate), vinyl monomers (styrene, methyl methacrylate), Tanalith-CBC, Phosphoric acid, Vacsol, Immersol, Polyethylene glycole (PEG-400) and their mixed solutions of chemicals in order to determine their combustion properties. The results indicated that inorganic boron compounds with aqueous solutions were very effective as fire retardant and reduced burning of some vinyl monomers at some extent such as styrene and methylmetacrylate when used as a secondary treatment chemical polimerized later on wood structure and phosphoric acid was also showed fire-reterdancy. Further studies are suggested on boron-vinyl monomers, and boric acid+borax with different concentrations by physical and chemical interactions in terms of fire reterdancy.
A Temiz, Ü C Yildiz


Oxygen index levels and thermal analysis of wood treated with melamine-formaldehyde-boron combinations
1997 - IRG/WP 97-30135
Melamine formaldehyde (MF) resin was impregnated into scots pine (Pinus sylvestris L.) specimens with aqueous solutions of 5, 10 and 20% concs. Boric acid (BA) and borax (BX) was added to MF resin at the concentration levels of 0.25, 1.00 and 4.70% to each level of resin concs. BA and BX mixture was prepared at the 5:1 (w/w) ratio considering resultant pH of solutions and better fire resistance. Untreated and treated wood with all combinations were subjected to oxygen index test according to ASTM D 2863-91 and thermal analysis. Results were evaluated in terms of improvement of fire retarding performances of wood by sole or combination treatments.
M K Yalinkilic, W-Y Su, Z Demirci, E Baysal, M Takahashi, S Ishihara


Wood preservation in China
1989 - IRG/WP 3546
Huiming Zhou, Zhongwei Jin


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


Bending Properties of FRT OSB
2012 - IRG/WP 12-40600
Fire retardant treated (FRT) oriented strandboard (OSB) and plywood of different widths were tested in static bending to determine width effects. Results were consistent with previous width effect studies and showed that increasing specimen width results in a decrease in sample MOR properties among all the sample groups tested in this study. Increasing sample width for OSB samples leads to more consistent MOR and MOE values. FRT plywood has a better width factor value than the two OSB sample groups tested in this study.
J M Hill, H M Barnes, S Q Shi


Serviceability modeling-Predicting and extending the useful service life of FRT-plywood roof sheathing
2000 - IRG/WP 00-20210
One of the most, if not the most, efficient methods of extending our existing forest resource is to prolong the service life of wood currently in-service by using those existing structures to meet our future needs (Hamilton and Winandy 1998). It is currently estimated that over 7 x 109 m3 (3 trillion bd. ft) of wood is currently in service within the United States of America (PATH 1999). Research programs throughout North America are increasingly focusing on understanding and defining the salient issues of wood durability and by maintaining and extending the serviceability of these existing wood structures. This report presents the findings and implications of a major 10-year research program carried on at the U.S. Forest Products Laboratory. This research program developed serviceability models for fire-retardant (FR)-treated plywood roof sheathing exposed to elevated in-service temperatures and experiencing thermal degrade. FR-treated plywood roof sheathing is often required by U.S. Building Codes in roof systems for multifamily dwellings having common property walls. This 10-year research program found many important facts. Qualitatively, the mechanism of thermal degrade in FR-treated plywood was acid-hydrolysis. The magnitude of strength loss could be cumulatively related to FR chemistry, thermal exposure during pre-treatment, treatment, and post-treatment processing and in-service exposure. The effects of FR chemistry could be mitigated by use of pH buffers. The strength effects were similar for many levels of plywood quality. Quantitatively, a kinetics-based approach could be used to predict strength loss based on its time-temperature history. This research program then developed models with which to assess current condition, predict future hazard based on past service life, and then predict residual serviceability of untreated and FR-treated plywood used as structural roof sheathing. Each of these findings is briefly described in this report. There are many opportunities for extending the useful service life of wood by better maintenance, remedial treatment, or enhanced serviceability assessment to predict both residual strength and residual utility. Results of research programs such as this can be used to extend service-life by providing the engineer with a estimate of residual serviceability and thereby avoiding premature removal. Many of the concepts employed in the development of these FR-plywood serviceability models are directly applicable to the development of predictive durability models for wood as affected by decay. When such a durability-based service-life model is developed, that serviceability model will aid building code officials, regulators, contractors, and engineers in determining replacement time schedules for wood undergoing biological attack.
J E Winandy


Effect of vapour boron treatment on mechanical properties of wood based board materials
1992 - IRG/WP 92-3727
The mechanical properties of Medium density fibre board, Chipboard and Oriented strand board were investigated after treatment to two retention levels of boric acid applied as a vapour phase system. A range of mechanical properties were investigated. The vapour boron treatment does not have any significant effect on most of the mechanical properties of the boards. The exception is a reduction in impact strength especially at the higher retention level.
R Hashim, D J Dickinson, R J Murphy, J Dinwoodie


Serial techniques for producing fire-retardant wood products
1997 - IRG/WP 97-30127
A series of techniques including fire-retarders denoted by WFR-1, WFR-2. WFR and their applications in producing fire-retardant wood (WFR wood), fire-retardant plywood (WFR plywood), fire-retardant particleboard (WFR particleboard) and fire-retardant MDF (WFR MDF) were investigated The fire retarders were low toxic, decay resistant and less leachable. The treated wood and WFR panels were of excellent fire resistance and good physic-mechanical properties. Besides formaldehyde released from WFR panels was very low.
Zhu Jia Qi, Liu Yan Ji, Gao Chao Ying


Fire retardant treated wood and plywood: A comparative study Part III. Combustion properties of treated wood and plywood
2002 - IRG/WP 02-40236
The fire retardant treated and untreated plywood and alder wood samples were prepared with the aim to investigate the effects of the way of treatment on the combustion properties. Alder wood was used for the preparation of plywood. Boric acid and borax were used as fire retardant. The plywood samples were impregnated by using three different methods; first group samples were impregnated by soaking of individual veneer before manufacturing plywood. The second group samples were impregnated by adding boron compounds into the glue mixture and third plywood group samples were vacuum impregnated according to ASTM D 1413-88. In addition, the solid alder wood samples were impregnated with same fire retardant solutions for control purpose according to ASTM D 1413-88. The results showed that the most effective way of the treatment was the impregnation of plywood panels treated with boric acid and significantly reduced burning of plywood and solid wood samples.
S Çolak, A Temiz, Ü C Yildiz, G Çolakoglu


Metal plate fasteners in trussed rafters treated with preservatives or flame retardants - corrosion risks
1977 - IRG/WP 3104
In designing roof trusses employing metal plate fasteners it is generally assumed that the roof will remain dry in service. Whilst this is generally true, damp conditions do arise under some circumstances, although it is not possible to quantify the extent of the risk. It is only possible, therefore, to give general recommendations which must be interpreted in the light of local experience of service conditions and site practice. Under severe conditions in the presence of moisture and salts, zinc coatings may not afford long-term protection against the electrochemical processes described above, and suitable precautions must be taken to minimise degradation. Moisture control is the most effective way of avoiding corrosion and if this can be achieved at all stages of manufacture, storage, and use, no diffculties should be encountered. If CCA treatments are employed, time must be allowed for the 'fixation' reactions to be completed before the plates are pressed into the timber. In cases where the assembly may become wet organic solvent preservative treatments are to be preferred in conjunction with metal fasteners. Those formulations which contain water-repellents will give added protection. Salt based flame retardant treatments should not be used in conjunction with fasteners, as the potential corrosion risk is too high. Connector plates manufactured from stainless steel may be considered for use in high-hazard situations. Finally, it has been shown at PRL that the use of nonconducting plastic coatings on the plates confers very considerable durability on these products, which may then be used successfully over prolonged periods under very adverse conditions. Such an approach may be well worth consideration in certain situations and further information on this method can be obtained from Princes Risborough Laboratory. This paper has been produced with the co-operation of the Agrement board, the International Truss Plate Association and the British Wood Preserving Association.
R A Laidlaw, L C Pinion


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