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Climate indices at work: Above ground decay L-joint tests (EN 330 and AWPA E9) at two sites 12000 km apart and with Scheffer climate indices of 60-65 and 300-330
1996 - IRG/WP 96-20095
Matched sets of Scots pine sapwood (Pinus sylvestris) L-joints were exposed above ground at two field sites for approximately five years. One site, at Garston, Watford, UK has a climate index between 60 and 65 while the other, close to Hilo, HI, USA has an index between 300 and 330. The joints were treated with a range of organic solvent treatments applied either by three minute dip immersion or by double vacuum. Untreated joints were installed at each site as control material. All samples were assessed at approximately annual intervals at both sites. After five years, decay at the Hilo site is well advanced with failure apparent in many joints, both untreated and treated. As would be expected given the climatic differences, decay at the Garston site has progressed more slowly than in Hilo. Differentiation in treatment performance was apparent after one year's exposure in Hilo with similar differentiation becoming apparent after five years' exposure in Garston. This acceleration correlates well with the difference in Climate Index for the two sites as calculated using the Scheffer method. Encouragingly, the performance ranking of the different treatments at the two sites was very similar. The results of this test suggest that the concept of using high decay hazard sites for field testing of treated wood products for use in above ground situations can provide meaningful results in a short period, and may offer a timely and realistic alternative to relative preservative testing to that achieved in laboratory test regimes. The results also show that above ground field testing at both of the sites included provide valuable information on preservative performance, and this information is likely to provide a greater degree of realism than is possible using pure culture laboratory test procedures.
A F Preston, K J Archer, D M Roberts, J K Carey, A F Bravery


A New Decay Hazard Map for North America Using the Scheffer Index
2008 - IRG/WP 08-10672
Wood decay experts in the USA and Canada use the Scheffer Index for above-ground wood decay potential to decide among design and treatment options to ensure the durability of wood construction. This paper provides an updated North American decay hazard map and includes data on Central America. Index values calculated from recent climate data are higher than published values due to directional or cyclical climate change. Compared to previously published maps there is considerable expansion of the moderate decay hazard zone in the interior wet belt of British Columbia, across the northern edge of the Prairies and around the Gulf of St. Lawrence. This suggests a greater need for preservative treatment in these parts of Canada.
P I Morris, J Wang


Decay Hazard Classifications in China for Exterior Above-Ground Wood
2007 - IRG/WP 07-20357
A decay hazard map for exterior above-ground wood structures is presented based on Scheffer’s Climate Index, with the major purpose of promoting awareness for proper protection of wood structures in different locations in China. A very large area in the South, including southern Yunnan, most of Sichuan Province and Chongqing, and part of Hunan, Hubei, Anhui, Jiangxi, and Zhejiang, as well as all the more southern areas, has decay hazard ratings above 70, considered a severe decay hazard zone according to the accepted classifications. The moderate decay hazard zone, Index values between 35 and 70, consists mainly of the central areas of China, from the west to the east, including parts of Xizang, Yunnan, Qinghai, Gansu, Shaanxi, Shanxi, Henan, Hubei, Anhui and Jiangsu, as well as Shanghai. It also includes most areas in Northeast China, together with a small pocket around Beijing. By comparison, large areas in the north, from the west to the east, including most areas in Xinjiang, Inner Mongolia, part of Qinghai, Gansu, Ninxia, Shaanxi, Shanxi, and Hebei, and a small part of Henan, are in a low hazard zone with index ratings below 35. The research demonstrates that the areas across China in the Southwest, South, Central China, Southeast, and Northeast, with the highest population densities and also containing areas on the east coast with the strongest economic development, have severe to moderate decay hazard for above-ground wood structures, making proper wood protection more critical and economically important.
J Wang, X Wu, M Jiang, P I Morris


To decay or not to decay: An accelerated field test of the validity of the Scheffer index
2008 - IRG/WP 08-20392
The Scheffer Index was introduced in 1971 to predict the relative decay hazard of untreated wood exposed above-ground. Precipitation and temperature parameters are used in the calculation. A higher Scheffer Index value implies a greater risk of decay. An accelerated 18-month study using seven field sites with Scheffer Indices ranging from 35 to 400 and two wood types (Populus tremuloides and Pinus spp.) was used to test the validity of the Scheffer Index. Different measures of decay including visual ratings, weight loss, and mechanical strength loss show that the Scheffer Index had varied success predicting the decay hazard. Visual ratings did not correlate with historical Scheffer Indices for the field sites. Aspen ultimate compressive strength had reasonably good agreement with historical Scheffer Indices, while static bend MOE and weight loss showed limited agreement. Southern pine static bend MOE and weight loss had good correlation to historical Scheffer Indices, but the ultimate compressive strength had limited correlation. It appears that historical Scheffer Indices more accurately predicted the decay rate for Pinus spp. than Populus tremuloides in this study.
G M Larkin, P E Laks


Decay hazard mapping for Europe
2011 - IRG/WP 11-20463
In this study, two different dose-response models for above-ground decay as well as a model transferring macro climate data to wood climate data are presented. The models base on data from field trials, which had been conducted at 28 European test sites, and were used to calculate the relative risk for decay caused by climate variability in Europe. The two dose-response models give coherent results when using either measured wood climate data or simulated climate data. The potential to simulate the relative risk of decay for different sites in the world from climate data has been demonstrated, even if no measured wood climate data is available. A preliminary decay hazard map has been generated to illustrate the climate induced variability within the European continent. For comparative purposes also the Scheffer Climate Index (SCI) had been applied to the same European data base. It was concluded that valuable information for service life prediction of timber structures will be gathered from performance-based decay hazard estimation and mapping.
C Brischke, E Frühwald Hansson, D Kavurmaci, S Thelandersson


Above ground testing at tropical test sites, what have we learned?
2011 - IRG/WP 11-20473
Three different above ground test methods have been utilized at a selection of five tropical and sub-tropical test sites with a variety of treated and untreated material. The results show that a multi-site approach to above ground field tests presents the opportunity for exposure to un-predicted biodeterioration hazards, which may be important for developmental products of poorly characterized fungicidal performance. The results also show that for tests exposed above ground on racks or fences, high climate index sites may benefit from canopy exposures of the samples rather than open field exposures. The Lap-joint test data from this study suggests that this method is a poor choice for providing rapid results even at test sites with high decay hazards
A Preston, A Zahora, Y Cabrera, L Jin, C Schauwecker, P Walcheski


Development of decay hazard maps based on decay prediction models
2016 - IRG/WP 16-20588
Durability plays a very central role in timber engineering, especially when working with wood in use class 3 and above where the risk of decay is high. As one of the primary decay influencing factors, the external condition, i.e. the local climate, is often graded by some type of climate index value. Predominately, climate indices are based on a direct relationship between weather data and decay. The aim of this paper was to develop a new type of climate index, including decay hazard maps, which explicitly considers the material climate. Firstly, the moisture content over time of a horizontal reference specimen was calculated using three different exposure models with weather data (rain, temperature, relative humidity) as input. Secondly, the output from the exposure models was post-processed using two different decay prediction models. Four different exposure model/decay-prediction model combinations were tested in total and repeated for many different locations in Northern Europe. Finally, the relative decay hazard between the different locations was calculated and interpolated, resulting in four preliminary contour plots visualizing the decay hazard in Northern Europe. The maps should be considered preliminary as they have not yet been verified against real decay data. The primary difference between the maps is the range of the relative decay hazard, i.e. the difference between the mildest and the most adverse conditions. The two extremes range between 0.6-2.6 and 0.8-1.8 respectively, which can be compared to the Scheffer index which ranges between 0.8-2.0. The next step, however not included in this article, is to compare the maps against real data.
J Niklewski, E Frühwald Hansson, C Brischke, D Kavurmaci


Observed and projected changes in the climate based decay hazard of timber in the United Kingdom
2020 - IRG/WP 20-20665
The risk of microbiological attack on wood is determined by both material and climatic factors and indeed the hazard for a component is based on its intrinsic durability and the conditions in which it is used. The use of wood and organic materials in construction is increasing but ultimately all these materials will be susceptible to microbiological attack. The Scheffer Climate index applies climatic variables such as temperature and wetting time to assess hazard zones within geographical areas. A changing and variable climate e.g. an increase in heavy but short duration rain events, may have an effect on the incidence or severity of microbiological attack and with the increase in the use of timber this could have significant impact on buildings and construction. This paper shows a significant increase in the Scheffer climate indices for various locations of the UK from 1990 to 2019. The highest index values are seen in the Northern and western areas of the United Kingdom, but increases are seen across the country. The paper also uses representative concentration pathway (RCP) scenarios to project future climate decay indices for the United Kingdom until the end of the 21st century. The projections show a significant increase in the climate decay index even in the lowest RCP scenario, with all regions of the UK moving to index values indicating a very high hazard based on climatic conditions
S F Curling, G A Ormondroyd


Modelling decay rates of timber exposed above ground on four different continents
2020 - IRG/WP 20-20670
Durability performance data from an international decking trial were analysed to explore relationships with climate variables, particularly those related to temperature and rainfall. Matched decking samples of slash pine (Pinus elliottii) sapwood and heartwood, spotted gum (Corymbia citriodora), Norway spruce (Picea abies) and Scots pine sapwood (Pinus sylvestris) were exposed to the weather above ground in Australia, Malaysia, Germany, Denmark and the United States. Boards were assessed periodically detect decay, which was rated using a common assessment scale. Preliminary exploration of relationships between decay assessment scores and decay indices – the Scheffer Climate Index and a dose-response model based solely on macroclimate variables – is presented in this paper. Shifting from a time-dependent analysis to one based upon cumulative macroclimate variables helped to better explain variations in performance among sites, although there were still some inconsistencies. Results are being further examined to help develop more precise predictive systems.
L P Francis, J J Morrell, C Brischke, P B Van Niekerk, J Norton


Field trial with poles of Scots pine treated with six different creosotes
1996 - IRG/WP 96-30115
In the middle of the 50's field trials with creosote-treated poles were started in France, Germany and Sweden. The trials were initiated by WEI (Western-European Institute for Wood Preservation). Six different creosotes were used and 40 poles per creosote were installed at each test field. Results after 39 years of exposure in Simlangsdalen, Sweden are reported. Poles treated with a heavy creosote were less decayed than poles treated with medium-heavy creosotes. Poles treated with a light creosote were most decayed.
Ö Bergman


A proposal for an international wood preservation standard
1994 - IRG/WP 94-20031
Two factors are driving the need for an international wood preservation standard. First, the global need to use our natural resources more wisely and second, the movement towards free trade exemplified by the General Agreement on Tariffs and Trade. The International Research Group on Wood Preservation is the ideal organisation to undertake the task of developing such a standard. This paper is intended to start this process. It attempts to bring together the best points of a number of national and international standards into a uniform format. Preservative penetrations and retentions for each commodity would be based on the hazard class/use category, the climate zone, the biological area, the natural durability of the heartwood of the species used, the service life required and the consequences of failure. The outline standard presented borrows heavily from the new European Standard and is presented as a possible starting point for the development of an international standard.
P I Morris


Preservative treatment of Eucalyptus saligna fence posts by the double-diffusion method
1982 - IRG/WP 3196
Eucalyptus saligna fence posts treated by the double-diffusion method with two chemical combinations showed average lives of 11.2 years (copper sulphate and potassium dichromate at 10.5 kg/m³ retention)and of 14.3 years (copper sulphate and sodium mono-H arsenate at 7.1 kg/m³ retention), as determined in five test sites in the State of Sao Paulo, Brazil. The exponential model was the best fit when expressing average life by the Decay Index (DI) as a function of time.
E S Lepage, A R De Freitas


Moulds and indoor climate in Denmark
2003 - IRG/WP 03-10488
Just like in many other countries after the oil crisis in 1972 Danish houses were tightened with the result that the relative air humidity rose considerably. The Ministry of Energy also demanded a lowering of the indoor temperature from 25°C to 20°C with the result that the relative air humidity rose even more. According to the latest survey 10% of Danish buildings are infected with moulds. Moulds occur in the indoor environment e.g. when humid air condensates on cold outer walls or in connection with water damage which is insufficiently dried out. In our analyses we always try to determine moulds both to genus and species. During our surveys in August 2001 and February 2002 we found 50 different species of moulds in Danish houses. The species Penicillium chrysogenum was dominating in both spring and autumn. Aspergillus versicolor was also present in spring and autumn but in smaller numbers. Cladosporium herbarum was most common during autumn. Stachybotrys chartarum was rather rare, maybe because it is closely connected to gypsum boards. It is very important to identify the moulds to species which is shown by the following case study. In a house where the sewer had been punctured in connection with establishment of district heating, 150 cubic metres of water had poured into the crawl space. We were called in by the occupant because she felt ill and there was a strong mouldy smell. We immediately asked her to move, with the result that her health improved almost instantly. She was so sensible that even the delivery of mail in her mailbox made her ill. A blood-test showed that she was sensitised to Trichoderma viride and Penicillium chrysogenum. The latter was found in large amounts in her house. We know that it is now possible to repair the house so that non-sensitised persons will be able to live there, but not the former occupant who will react to even small traces of allergen which are still there. After the repair we have different methods of quality control. It is now evident that some remedies and methods will kill the spores others the mycelium and yet others both. Some methods have a lasting effect, others do not. Our methods of quality control are either contact-samples with Petri dishes where mould colonies are counted and identified to species or a test for ATP or the Mycometer-test where the enzyme β-N-acetylhexosaminidase specific to fungi is measured. The Petri dish method measures the number of living spores, while the two other methods measure the amount of mycelium. However it seems that ATP in the mycelium is broken down faster than the enzyme measured by the Mycometer-test. Therefore it becomes difficult to decide whether the mycelium is living, partly dead or completely dead, when the repair work is going to be approved.
J Bech-Andersen, S A Elborne


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


Seasonal effects of the field evaluation on wood preservatives against mold fungi
1996 - IRG/WP 96-20087
For the purpose of the amelioration of field test methods, commercial preservatives against mold fungi were tested under two different seasons, in winter and in summer. The specimens were bundled and set over the water bath and all these systems were covered with plastic film. At top of the system under film, black films for regeneration of sunlight were put in, and windows for changing air were reserved in summer. The visual evaluation of damage (rating 0-4) was done periodically. The results obtained as follows. 1.) The evaluation values after 2 months in winter were simmilar results as those after 3 weeks in summer. 2.) The fungicides, mixture of nitoril compound and organo nitrogen sulfuric compound, mixture of thiocyanate compound and organo nitrogen sulfuric compound, were obtained good results in field. Those percentage of the specimens rating under 1 were more than 50% and those mean rating were not more than 2. 3.) In the case of organo iodide compound, the results in winter were good but in summer were not so good.
K Suzuki, Y Sugai, K Ryugo, D Watanabe


Performance of treated spruce in Canadian field test sites
1989 - IRG/WP 3506
Spruce material under test in Canadian field test sites is performing better than anticipated. From the comparison of the performance of spruce treated with various preservatives, it appears that penetration may be far more important on durability performance than the preservative itself or the retention of preservatives in the wood. However, there is still insufficient data on the influence of penetration on the performance of treated spruce. As data for species other than white spruce and data for sawn material is also incomplete, spruce cannot be accepted by the Canadian standards at this time.
J P Hösli, E E Doyle


Evaluation of termiticides in field trials
1990 - IRG/WP 3633
Termiticide-treated posts and stakes have been tested at the field test site in Kagoshima, Southern Kyushu, Japan. Various commercial and alternative termiticides have been evaluated annually as TAI (termite attack index), calculated by the equation: TAI = R x P, where R is the mean of attack rating of 0 (sound), 10 (sign of tasting), 30 (slight attack), 50 (moderate attack), 100 (severe attack), and P is the ratio of attacked posts (stakes) to total posts (stakes) tested, expressed as 0.0-1.0 . CCA-impregnated Japanese cedar (Cryptomeria japonica) posts have well performed keeping 0 TAI over nine years. AAC-treated pine (Pinus radiata) stakes with 9.3 kg/m³ DDAC (didecyldimethyl ammonium chloride) or 9.4 kg/m³ BTAC (methylalkylbenzyltrimethyl ammonium chloride) have been free from decay, but they yielded 34 or 42 TAI after eight years. Improvement of termite resistance was revealed by addition of cupric chloride or cuprammonium chloride. Brushing treatment of pine (Pinus densiflora) stakes, with 200 g/m chlordane (2.0%), chlorpyrifos (1.0%) or tetrachlorvinfos (1.0%) solutions, did not provide the perfect control for five years, yielding 30, 42 and 48 TAI, respectively.
M Takahashi, Y Imamura, K Tsunoda, A Adachi, K Nishimoto


The evaluation of the occurrence of soft rot in creosoted wooden poles
1988 - IRG/WP 1368
The occurrence of soft rot decay in creosoted wooden poles for overhead power lines was investigated by collection of field samples, their subsequent microscopic examination and statistical analysis of the data collected. Examination of samples collected from 296 poles revealed that approximately 15% of the pole population studied (Eastern Electricity Board) showed the presence of soft rot decay. Further, it was found that of undated poles, (those emplaced before 1953,) 17% displayed soft rot attack.
A Wylde, D J Dickinson


List of wood-destroying fungi in Iran
1976 - IRG/WP 138
This list gives information on the wood-destroying fungi collected in the Iranian forests and from felled logs and boards in sawmills until now. They are mainly from the region of the Caspian Forests and from the climatically dry region between Teheran and Azarbaidjan, North Iran. It is understood, that this document may help to give more knowledge outside the country about the specific problems of Iran, or concerned with the regions of the Middle East with great varieties of climate. The collection, which is far from complete, includes 76 species of fungi belonging to 46 different genera. Several of the species have been published already nationally, some internationally. Some species have just been recognised recently in Iran and are mentioned for the first time. These species are marked with (+). All samples of fungi collected are conserved and kept in the laboratories of the Department of Wood Science at the Faculty of Natural Resources, Karadj. Their identification was undertaken by the author and with help of the Centre Technique du Bois, Services des Recherches et Essais (Lab Mycologie du Bois), Paris, and of the Royal Botanic Gardens, Kew.
P Soleimani


Calculation of preformance index of Bardac 20 (an alkylammonium compound) evaluated in a field stake test
1982 - IRG/WP 3206
Bardac 20 treated stakes have been in test for three years at the Westham Island test site near Vancouver, B.C. The Performance Index for the preservative was calculated and found to be 0.009 which infers that, at the standard retention, Bardac 20 added 0.9 y to the life of the stake. It may be concluded that when tested using a standard field stake test using ponderosa pine (Pinus ponderosa Laws) sapwood at a standard retention of 6.35 kg/m³ Bardac 20 did not fulfil the expectations indicated from the laboratory screening test conducted earlier. Studies are in progress to determine the cause of this discrepancy in performance with a view to improving this class of compound as a wood preservative for use in ground contact situations.
J N R Ruddick


Fungus cellar testing as an evaluation method for performance of treated timber in ground contact
2001 - IRG/WP 01-20227
A fungus cellar method for the accelerated evaluation of performance of treated wood in ground contact is described. The test soil comprised of sandy loam, vermiculite and Japanese horticulture soil "Kanumatsuchi" in a ratio of 6:2:2 by volume. The soil was inoculated with the dominant test fungus isolated with selective medium from decayed wood samples. Pairs of treated and untreated wood specimens Japanese cedar in contact with each other were buried vertically for two thirds their length. Assessment of the specimens was carried out periodically using the FFPRI graveyard damage index six- grade scale. Important factors for accelerating decay were the moisture control of the mixed soil, temperature and relative humidity, and the maintenance of fungus activity. The fungus used for inoculation favored a soil water holding capacity (WHC) of 50-80%. Under these conditions the untreated control specimens had a damage index in six months equivalent to three years FFPRI graveyard test service life, the decay accelerating rate by the fungus cellar to the graveyard test was 6 times. Under higher soil moisture conditions (WHC>80%) in the fungus cellar, soft rot was dominant and the decay rate was slower. DDAC treated specimens (8.4kg/m3) had a damage index of 2.6 in three years and 3.0 in four years. DDAC treated specimens (8.2kg/m3) in the graveyard test have been shown to be durable for 12 years (damage index of 2.3 in ten years and 2.6 after 12 years). This fungus cellar method has been shown to accelerate decay in DDAC treated specimens 3 times or more in comparison to the FFPRI graveyard test. On the other hand specimens treated with Copper-azole (6.0kg/m3 as retention of actives) had a damage index of 0 after eight years. The average service life in the FFPRI graveyard test is not decided as the Copper-azole treated specimens are in sound condition so it is not yet possible to evaluate the accelerating rate for the Copper-azole by the fungus cellar method. The fungus cellar method will be an useful method for the accelerated evaluation of performance of treated wood in ground contact provided the test conditions can be controlled.
Y Nagano


Natural weathering of wood in a sunny climate effects on surface chemistry and paint adhesion
1997 - IRG/WP 97-20109
Radiata pine veneers and blocks were exposed to natural weathering under Australian summer conditions over a period of 30 days. Infrared spectroscopy revealed that there was perceptible surface delignification after 4 hours exposure, substantial surface delignification after 3 days exposure and almost complete surface delignification after 6 days. Viscometry determinations on holocellulose samples from weathered veneers and unweathered controls indicated significant depolymerisation of cellulose after short periods of weathering. A tape test was used to assess the adhesion of acrylic latex primers to weathered blocks. The adhesion of exterior acrylic primers decreased on weathered wood surfaces and was significantly lower on specimens that were weathered for 5 to 10 days. An oil-modified acrylic primer showed greater adhesion to weathered wood surfaces. Primer adhesion was lower on weathered radial surfaces than on similarly exposed tangential surfaces. The practical implications of these findings for the coating of exterior wood with acrylic latex primers and the development of photoprotective treatments for wood are discussed briefly.
P D Evans, P D Thay, K J Schmalzl


Field testing of alkylammonium wood preservatives
1983 - IRG/WP 3248
The field test performance of five alkylammonium wood preservatives is described. The relative effectiveness of three unmodified formulations was determined by calculation of a Performance Index. Of the three, didecyldimethylammonium chloride was found to be superior to octyldecyldimethylammonium chloride, and both were more effective than alkyltrimethylammonium chloride. However, none were considered to have potential for use as wood preservatives. The addition of cupric chloride to octyldecyldimethylammonium chloride did not improve its effectiveness. Initial results for alkyldimethylbenzylammonium chloride modified by the addition of tributyltin chloride indicated that the preservative performance may be significantly improved.
J N R Ruddick


Determination of the water sorption properties and preliminary results from field tests above ground of thermally modified material from industrial scale processes
2004 - IRG/WP 04-40279
In this study the differences in moisture behavior and durability above ground of heat treated wood originating from different European industrial heat treatment plants by means of the water sorption properties as well as field tests were examined. The manufacturers of heat treated material were: PLATO Hout B.V./Netherlands, Thermo Wood (Premium wood)/ Finland and Menz Holz/ Germany, where Oil-Heat treated Wood (OHT) is produced. Temporary evaluation of field tests showed a substantially improved resistance against biological attack of the thermally modified material compared to controls. The results of the laboratory tests regarding the determination of the Moisture induced Risk Index (MRI) showed a significantly reduced MRI of heat treated material compared to references. Material from the PLATO process and Oil-Heat treated material revealed significantly lower MRI values than Thermowood. Natural weathering above ground had so far no significant influence on the MRI of thermally modified specimens compared to the initial values.
C R Welzbacher; A O Rapp


Wood preservation in Portugal
1985 - IRG/WP 3325
This report deals with the forest potential of Portugal and its timber industry and outlines the evolution of wood preservation in the country. The main hazards to timber in service are noted and the timbers used classified according to their natural durability and treatability. The wood preservatives used are detailed with estimates of the total consumption of the different types. Addresses are listed, of the known manufacturers and importing agencies, of the firms that treat by vacuum/pressure and those that employ the double-vacuum process, and of the organizations concerned with wood preservation research and wood preservation in general. Only two firms specialize in remedial treatments and there are two institutions which are responsible for restoring cultural properties. Information is given on requirements and approvals. The relevant standards are listed and the main Portuguese papers on wood preservation.
D De Sousa Castro Reimão, R Cockcroft


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