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Effectiveness of copper/chromium salts as wood preservatives against Limnoria tripunctata Menzies in laboratory tests
1977 - IRG/WP 431
During the last joint meeting of IRG and COIPM a co-operative programme of tests with copper/chromium salts as wood preservatives against marine borers was discussed and agreed. In this connection the results of a laboratory test in the BAM with Limnoria tripunctata Menzies will be of interest. But as the respective paper is written in German (H. Kühne; G. Becker: Laboratoriumsversuche über die Wirkung kupferhaltiger Schutzsalzgemische auf die Holzbohrassel Limnoria tripunctata Menzies) (Material u. Organismen 5 (1970) No 4, 307-319) a comprehensive summary is given in English for IRG-COIPM members.
H Kühne


Marine trials with water-borne salts and organotin compound
1986 - IRG/WP 4128
Pinus sylvestris blocks treated with water-borne salts (CCA, CCB, CCF) and organotin compounds (TBTO, TBTCl) were submerged in the sea at Follonica station. The results obtained after 12 years of immersion are presented. The samples treated with CCA, CCB and CCF at the lowest concentration (2%) were destroyed after 7-9 years and the samples treated with CCB and CCF at the highest concentrations (4%, 6%), which were tested for a longer time than CCA treated samples, were destroyed after 11-12 years. The samples treated with organotin compounds did not show any attack by molluscan borers after 12 years with the exception of those treated with TBTCl at the lowest concentration (0.5%). The organotin compounds were less effective against crustacean borers.
A Gambetta, E Orlandi


The relationship between the electrical resistance and fixation of water-borne CCA salts and pressure-treated wood
1991 - IRG/WP 3657
Two investigations at 22°C and 30°C have been carried out. The electrical resistance in the treated wood and chemical analyses of the remaining amount of unfixed copper, chromium and arsenic were investigated. Samples impregnated with water were used as references. To hold the samples moist during the investigation, each sample was wrapped in a polyethylene plastic foil immediately after impregnation. The electrodes were of acidproof steel. The fixation was also checked by chemical analyses. The result shows that the electrical resistance increases during the fixation, as the concentration of the unfixed metal ions decreases, and that it stabilizes at the same time as there are almost no free unfixed metal ions in the samples. It is therefore possible to measure the fixation by using the electrical resistance given, that the temperature and moisture content in the sample is constant.
F G Evans, B Nossen


Disproportionate absorption of different constituents of CCA salts
1988 - IRG/WP 3484
Results of preliminary experiments carried out to study selective absorption of different constituents of CCA salts and sludge formation in commercial treatment, using Terminalia myriocarpa and Pinus kesia timbers, are reported in this paper. The objective of these experiments is to evolve simple and practical methods to prevent/minimise sludge formation and differential absorption of the constituents of the preservative in commercial treatments, without affecting the efficacy of the treatment. The results so far obtained indicate that there is disproportionate depletion of the constituents of CCA with successive charges. Further detailed investigations are in progress to study these aspects to evolve guidelines to ensure better quality control in commercial treatments. As per current practices the different ingredients of the preservative have to be replenished as and when necessary.
V R Sonti, S Sonti, B Chatterjee


Tropical In-Ground Durability of Structural Sarawak Hardwoods Impregnated to High Retention with CCA-salts, CCA-oxide and FCAP after 20 Years Exposure
2005 - IRG/WP 05-30384
Statistical analysis (ANOVA) was conducted on durability (termite and decay combined) rating data collected over 20 years exposure period of over 140 species of Sarawak timbers with altogether 30,000 stake specimens, at the Forest Department’s Sibu “graveyard” stake test sites from 1977. About 20 replicated stakes were pressure-treated to refusal with 10% g/ml concentration of up to 3 CCA-salt formulations and 1 CCA-oxide product and FCAP were visually evaluated every 6 months according to the 5-point ASTM D1758 durability rating scale, and the treated durability results reported in this paper are between 5 and 20 years exposure. The analysis was confined to 7 relatively high density hardwood species that are regarded suitable for in-ground structural use (ie, basic density >600 kg/m3), and had achieved a minimum preservative retention of 16 kg/m3 (as required for CCA-salts) but up to 48 kg/m3 retention. The results revealed that the in-ground durability of treated wood decreased usually after 5 years to poor-to-moderately durable levels with CCA-salts, moderate-to-high durability with CCA-oxide, but failed with FCAP after 20 years. CCA-oxide treated hardwoods out-perform the CCA-salt treated counterparts despite their relatively similar retention and “over-treatment factor”. The non-leach-resistant FCAP is clearly unsuitable as an industrial used in-ground wood protectant.
Wang Choon Ling, A H H Wong


The future for chromium in wood preservation
1985 - IRG/WP 3332
Most water-borne preservatives contain CrVI compounds, originally to reduce corrosion although now also to improve toxicant fixation. Chromium contributes to preservation and this is recognised in, for example, New Zealand and USA where chromium contents are included in calculations of overall preservative activity of CCA formulations, but chromium may also have anti-stain and joinery (millwork) primer functions. CrVI can represent health and environment risks but only if a preservative is carelessly handled; chromium is fixed in treated wood which does not present a risk. CrVI is essential for fixation in preservatives such as CCA formulations but the development of new preservative uses for chromium should be directed towards CrIII which is virtually nontoxic.
B A Richardson, T R G Cox


A comparison of soft rot, white rot and brown rot in CCA, CCP, CCF, CCB, TCMTB and benzalkonium chloride treated Pinus radiata IUFRO stakes, after 9-15 years exposure at five test sites in New Zealand
1991 - IRG/WP 1485
The aim of this study was to determine if decay type varies significantly between five field trial test sites of different soil type, aspect and climate in 9-15 year old, replicate CCA, CCF, CCP. CCB, TCMTB and AAC treated IUFRO stakes. A visual on-site assessment of decay type on every test stake was made and observations confirmed by microscopical examination. Regression analyses were used to determine significant differences of percentage frequency of occurrence of each rot type between sites and preservatives. Large differences in percentage frequency of occurrence of rot type were evident between sites. One site was dominated by brown rot (85%) and two were dominated by soft rot (99 and 91%). The fourth site had intermediate proportions of brown rot (40%) and soft rot (71%) but had the second highest occurrence of white rot (32%) (highest = 37%; lowest = 11%). The fifth site was distinct in that a large proportion of stakes (69%) had both well established brown rot and soft rot. Stakes at the other four sites tended to have only one rot type. Some highly significant preservative effects were also found. Possible causes of these differences are discussed in terms of inter-site soil type, climate and other differences.
R N Wakeling


IRG/COIPM INTERNATIONAL MARINE TEST - to determine the effect of timber substrate on the effectiveness of water-borne salt preservatives in sea-water. Progress Report 2: Report of treatment and installation in Australia
1978 - IRG/WP 440
The purpose of this test and the procedures to be followed have been fully set out in documents distributed by the International Research Group on Wood Preservation and numbered IRG/WP/414 and IRG/WP/420. The prescriptions set out in these two documents have been closely followed.
J Beesley


Marine testing of selected waterborne preservatives
1987 - IRG/WP 4137
In 1978 a marine test was established at West Vancouver, B C. to determine the performance of selected waterborne preservatives. The preservatives in test were chromated-copper-arsenate (CCA-C), ammoniacal copper arsenate (ACA), a modified formulation of ACA which contained a higher copper content (modified ACA), ammoniacal copper zinc arsenate (ACZA) and ammoniacal zinc arsenate (AZA). The wood species used for the test was red pine. After eight years in test the CCA is providing excellent performance at all retentions, while the modified ACA is showing significant deterioration only at the lowest level. The ACA is performing quite well although it shows signs of surface deterioration at all retention levels. The performance of the ACZA is rated as unsatisfactory at retentions below 32 kg/m³ while AZA was considered to be unsuitable for use in the marine environment.
J N R Ruddick


Manual of a mini treating plant for waterborne preservative treatment of timber and bamboo
1999 - IRG/WP 99-40130
This contributional article includes machinaries and equipments necessary for a small wood treating plant for the pressure treatment of tim bers with waterborne preservatives along with the cost and design. The preservative treatment limitations, treatment schedules and specifications for different products have been described. The cost of a mini treating plant will be 6,00,000 Tk. (13,000 US$), suitable for preserving timber and bamboo products for indoor and outdoor uses and will out last teak wood. The additional durability of timber and bamboo will create economically and environmentally safe conditions.
A K Lahiry


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


Strength loss associated with steam conditioning and boron treatment of radiata pine framing
1987 - IRG/WP 3438
The combined effect of included defects and wood moisture content on the strength loss of second rotation radiata pine framing following conventional steam conditioning is investigated. The green Modulus of Elasticity (MOE) is reduced by approximately 13% after steaming. When dried after steaming, however, neither the MOE nor MOR is significantly different from unsteamed dried controls.
M J Collins, P Vinden


Collaborative soft rot tests: PRL tests of Cu/Cr/As preservative using method of Document No: IRG/WP/208
1973 - IRG/WP 223
These tests were undertaken as a preliminary to the next series of collaborative soft rot tests. An interim report has already been presented at Berlin in 1972 as Document No: IRG/WP/211
J K Carey, J G Savory


Japan's comments on ISO/DIS 12583-1/2
1996 - IRG/WP 96-20100
The paper describes an accelerated field test for the evaluation of timber preservative formulations against subterranean termites. The method has been adopted by the South African wood preservation industry as a screening method for the approval of wood preservatives for use under SA conditions. The method which is based upon the fungal cellar test offers a rapid means of evaluating the comparative performance of new wood preservative formulations in an environment that accurately reflects field conditions.
P Turner, D Conradie


Soft rot in CCA-treated utility poles in Sweden
1989 - IRG/WP 1398
Soft rot investigations of CCA-treated utility poles (Pinus sylvestris L.) have been conducted throughout large parts of Sweden during 1974-1985. The investigation included 179 utility poles of the State Power Board which had been used for 10-18 years in the different administrative regions from northern to southern Sweden. In addition, 193 telephone poles from the Östersund area and 218 from the Kristianstad area were studied after having been in use for 18-25 years. The soft rot fungi cause two types of attack in wood cells, namely cavities (Type I) and erosion (Type II). In this investigation, soft rot is reported only when cavities of Type I were found. Erosion (Type II) is more difficult to observe, particularly in early stages, and in addition is almost impossible to distinguish from certain other attacks of rot, such as white rot, which may have occurred during storage of the poles before impregnation. In western and central Sweden, minor attacks of soft rot were found after 10-12 years in State Power Board poles embedded in soil in arable land and meadows. Power Board poles in northern Sweden had minor attacks of soft rot after 16-18 years in arable land and also in forest land when embedded in soil. Poles used by the Telecommunications services, all embedded in stone, showed minor and only occasional attacks of soft rot at Östersund (northen Sweden), but considerably more soft rot at Kristianstad (southern Sweden). The Telecommunication poles had been in service up to seven years longer than the poles used by the State Power Board. The localization and spread of soft rot attacks in a pole can vary. There may be many reasons for this, including insufficient impregnation, leaching, etc. The soft rot attacks found in the Power Board poles are always minor and sporadic and none of the investigated poles can be said to imply any safety risk. The same applies to the Telecommunication poles at Östersund whereas those at Kristianstad demonstrated considerably more severe and more frequent attacks. The attacks of soft rot in the Telecommunication poles more frequently occurred internally, more often deeper in the sapwood than in the outermost parts.
H Friis-Hansen, H Lundström


Fungal and bacterial attack of CCA-treated Pinus radiata timbers from a water-cooling tower
1991 - IRG/WP 1488
Transmission electron microscopy of decaying CCA-treated Pinus radiata timbers from an industrial water cooling tower showed presence of a thick biofilm covering some areas of the wood. The biofilm contained various morphologically distinct forms of microorganisms embedded in a slime. The study provided evidence of the activity of soft rot fungi and tunnelling and erosion bacteria in wood cells. The extent of damage to wood cells due to microbial activity varied, combined fungal and bacterial attack having the most damaging impact.
A P Singh, M E Hedley, D R Page, C S Han, K Atisongkroh


International collaborative laboratory comparison of two wood preservatives against subterranean termites: Third update and first report
1996 - IRG/WP 96-10174
At the 24th annual meeting of IRG in Orlando, USA, in May 1993 an international subterranean termite laboratory bioassay to compare the various preferred termite protocols used by IRG termitologists was initiated. The author was nominated to co-ordinate this comparative laboratory evaluation of two wood preservatives, copper-chrome-arsenic (CCA) and copper naphthenate (Cu-Na) against the subterranean termites used as test termites in Australia, France, Japan, Thailand, United Kingdom and the Unites States of America. Solutions of these two wood preservatives were prepared and impregnated into Pinus radiata wood blocks to obtain loading of 0.0, 0.5, 1.0, 2.0 and 4.0 kg/m³ respectively. All preservative treatments were carried out at the Division of Forestry and Forest Products in Melbourne. The treated specimens were dispatched to the participating researchers who subjected these specimens to attack by their test termite species, and have now returned the specimens to Melbourne. This paper reports the amount of wood consumed and the mean mass loss (%) on both treated and untreated wood blocks by the termites in the various laboratory bioassays.
J R J French


IRG/COIPM INTERNATIONAL MARINE TEST - to determine the effect of timber substrate on the effectiveness of water-borne salt preservatives in sea-water. 2nd Interim Report
1981 - IRG/WP 477
Three reference wood species - Alstonia scholaris, Fagus sylvatica and Pinus sylvestris, untreated and treated with 3%, 6% and 10% CCA and CCB solutions were supplied to all participants for submergence at local sites. Regular examination of samples is being carried out - 6 months, 12 months and then annually for 7 years.
R A Eaton


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


Types of decay observed in CCA-treated pine posts in horticultural situations in New Zealand
1984 - IRG/WP 1226
The few reported failures of 11-12-year-old horticultural posts in New Zealand in 1982 were caused by brown-rot. A subsequent survey of CCA-treated posts in all the major horticultural areas has revealed decay of many posts. A microscopic examination of these posts has shown decay by brown-rot, white-rot, soft-rot and bacteria. Several types of bacterial decay have been observed.
J A Drysdale, M E Hedley


Electrodialytic remediation of creosote and CCA treated timber wastes
2002 - IRG/WP 02-50190
There is a growing concern about the environmental issue of impregnated timber waste management, since an increase in the amount of waste of treated wood is expected over the next decades. Presently, no well-documented treatment technique is yet available for this type of waste. Alternative options concerning the disposal of treated wood are becoming more attractive to study, especially the ones that may promote its re-use. Inside this approach, the electrodialytic process (ED) seems a promising technique for removal of preservative chemicals from treated wood waste. The method uses a direct electric current and its effects in the matrix as the “cleaning agent”, combining the electrokinetic movement (mainly due to electromigration, but also electro-osmosis and electrophoresis), with the principle of electrodialysis. This work reports results from the application of the electrodialytic process to an out-of-service Portuguese creosote and CCA-treated Pinus pinaster Ait. railway sleeper and pole. The behaviour of the process is described and the main results discussed. The average removal rate, estimated in accordance with prEN 12490, for creosote from treated timber waste was around 40 %.. For CCA treated timber waste, experimental conditions that could optimise the process efficiency (e.g. current density, time) were studied. The highest removal rates obtained until now, in our studies, were 93 % of Cu, 95 % of Cr and 99 % of As for sawdust using 2.5 % oxalic acid (w/w) as the assisting agent. For CCA treated wood waste in the form of chips, the best removal rates obtained until now were 84 % of Cu, 91 % of Cr and 97 % of As.
E P Mateus, A B Ribeiro, L Ottosen


Termite resistance of pine wood treated with chromated copper arsenates
1997 - IRG/WP 97-30128
Two four-week, no-choice laboratory tests were performed with CCA-treated southern yellow pine and radiata pine against Formosan subterranean termites, Coptotermes formosanus. CCA retentions as low as 0.05 kg/m3 (0.03 pcf) provided protection from all but light termite attack (rating of 9 on a 10-point visual scale). Similar and consistent light attack on wafers containing retentions as high as 6.4 kg/m3 (0.4 pcf), coupled with complete termite mortality, demonstrates that the mode of action of CCA treatments relies upon toxicity rather than having any repellent effects against termites.
J K Grace


IRG/COIPM INTERNATIONAL MARINE TEST - to determine the effect of timber substrate on the effectiveness of water-borne salt preservatives in sea-water. Progress Report 13: Report of fourth inspection (36 months) in Australia
1981 - IRG/WP 481
This report presents the results of the fourth inspection of the IRG/COIPM International Marine Test specimens installed in Sydney Harbour in December, 1977. The inspection took place on 9th December, 1980, after 36 months exposure. Full details of the treatment and installation of the specimens, as well as results of the first three inspections (after 6, 12, and 24 months exposure), have been presented in earlier reports. All inspections of this test have been carried out in accordance with the Working Plan (see IRG/WP/414) except for an X-ray examination of the specimens. This facility is not available at the test station. In conformity with the provisions of the Working Plan, the fifth and sixth replicates of the whole test (i.e. those specimens with '5' or '6' as the final digit of their serial number) were recovered and returned to the United Kingdom after 6 months and 24 months of immersion. Thus, only four replicates remain to be examined at this and ensuing inspections.
J Beesley


Application of radio frequency heating to accelerate fixation of CCA in treated round-wood
1999 - IRG/WP 99-40133
The potential of radio frequency heating to accelerate the fixation of chromated copper arsenate (CCA) in treated round-wood was assessed. Pre-dried Douglas-fir and western red cedar round-wood sections were pressure treated with CCA in a pilot plant retort, after which they were placed individually in a pilot radio frequency (RF) chamber. Based upon the color reaction of chromotropic acid with hexavalent chromium and the quantitative assessment using diphenyl carbazide, fixation was achieved in less than 6 hours. During heating, the temperature at various locations inside the pole sections was monitored by fiber-optic thermocouples. The moisture profiles before, and after fixation, were also recorded. Further studies will examine other benefit of RF heating, including a) sterilization, and b) rapid drying of round-wood with minimum check formation.
Fang Fang, J N R Ruddick


Improved equipment and technique for high pressure sap displacement impregnation of natural round wood
1972 - IRG/WP 309
Hitherto the main problem in the practical application of high pressure sap displacement impregnation (HPSD) has been in devising a satisfactory cap. Such a cap must be easily fitted to different size log ends to give a leak proof seal. The present contribution describes a new type of cap and sealing system designed to meet these requirements.
C G W Mason, F B Shorland


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