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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


An investigation concerning Camponotus spp. distribution and damage in buildings in Sweden
1985 - IRG/WP 1248
This is a report of an investigation by a Swedish insurance company on the occurrences of damage by Carpenter ants during 1974 to 1981. The distribution of damage in walls, roofs and floors of both permanent homes and summer-houses has been assessed. It is concluded that the increased frequency of attack is becoming economically serious.
V Butovitsch, K-J Hedqvist, C Tornberg


Wood decay in Danish buildings
1985 - IRG/WP 1261
At Technological Institute identification of fungi and advisory activity concerning repair of damages has taken place since 1935. Statistical analyses based on material from 1982 and 1983 are compared to earlier investigations worked out by L. Harmsen. The material shows that building traditions influence the diversity and frequency of fungal species. Many fungal damages in the last decade have showed that it is very important to use timber in a suitable manner not forgetting old building traditions. The conditions of fungal attack must be analysed and followed up by improvement of constructive and chemical wood protection.
A P Koch


TBTO absorption and penetration in pine joinery treated by various processes
1989 - IRG/WP 3523
Matched sections of several White pine (Pinus strobus) and Ponderosa pine (Pinus ponderosa) mouldings were treated with TBTO by Double vacuum, modified empty-cell, 15 second dip and several preheating treatments followed by a 15 s dip treatments. As expected the double vacuum and empty-cell (batch) treatments resulted in much greater retentions and penetrations than the dip treatments. The absorptions by the 15 s dip treatments could be improved significantly by preheating the wood to 60-90C° by microwave, radio-frequency or infra-red techniques. Since this approach is amenable to a continuous treatment process, it is being evaluated for potential commercial application.
P A Cooper, Y T Ung


Occurrence, prevention and repair of Dry Rot
1990 - IRG/WP 1439
Information about the frequency, detection, identification and repair of Dry Rot attacks (Serpula lacrymans) is summarized from 13 European countries. Based on 28 completed and returned questionnaires it appears that Dry Rot attacks are recognized in all countries participating, and that there is an appreciable similarity in the frequency of attacks and methods of detection and identification. However, the method of repair is often rather different between the countries and sometimes even within the same country. These differences are reflected in the methods of repair as well as in the chemical treatment to prevent further spread of the attack. Research concerning alternative methods of Dry Rot treatments is only performed in a few countries.
A P Koch


Radio frequency heating times for sterilization radiata pine solid piles
2017 - IRG/WP 17-40815
In this work was sterilized wood packaging material of radiata pine, stacked as solid piles without stickers, for determining the heating times using radiofrequency treatment. The experiments were performed in a radio frequency semi-industrial equipment. The results showed that the radio frequency heating times increases with wood volume and that radio frequency treatments were faster than conventional vapour heat treatment.
H Esquivel, V Sepúlveda, J Torres, L Salvo, R A Ananías


Experiences from a Danish large scale test by means of a new method of treatment by attack of true dry rot fungus (Serpula lacrymans) in buildings
1994 - IRG/WP 94-10064
Experiences from a new and epoch-making method of treatment in connection with the repair of attack of the true dry rot fungus, Serpula lacrymans (Fr.) S.F. Gray, are described. The paper presents the background of a large scale test comprising repair of more than 150 Danish buildings over a period of approximate 5 years. The method being both gentle to the building and presenting savings of at least 70% compared with the traditionally known repairing methods is based on thorough recording of the extent of attack and examination of the vitality of the fungal attack combined with a changed chemical and constructive treatment including treatment by means of a newly developed heat treatment based on high frequency radio waves. Continuous controls have confirmed the applicability in practice of the method. Beyond the method, the paper discusses the consequences as regards security, possibilities of insurance and obtaining a mortgage loan.
O Munck, H Sundberg


Eradication of wood decay fungi by means of radio frequency
1998 - IRG/WP 98-10292
High frequency electromagnetic fields i.e. radio frequency (RF) are used in wood industry for heating, gluing and bending of wood and are also appropriate for eradicating of wood decay fungi and insects. We investigated the effects of RF exposure on wood samples which were in vitro infected by Coniophora puteana, Gloeophyllum trabeum and Lentinus lepideus. For each fungus, the lethal temperature and time of exposure were determined. The efficacy of RF treatment was visually evaluated from regeneration of mycelia by subsequent exposure of treated wood samples on growth media. The eradication was dependent on the fungus species, temperature and duration of exposure to RF of 4.75 MHz. The most sensitive was Coniophora puteana (destroyed in 4 minutes at 75°C), less sensitive Lentinus lepideus (in 10 minutes at 90°C) and the least, Gloeophyllum trabeum (in 12 minutes at 90°C). At low temperatures, the time of exposure had to be adequately longer.
F Pohleven, J Resnik, A Kobe


Questionnaire relating to the occurrence, prevention and repair of Dry Rot attacks in buildings
1989 - IRG/WP 1418
Dry Rot attack in buildings has become an increasing problem in Denmark. The reason is that old multi-storey houses from about 1890-1920 are being renovated and modernised and connected to this well-hidden Dry Rot attacks are detected. The traditional methods for repair used in Denmark are very expensive but with a high degree of confidence when done carefully. There is a big need for development of alternative methods that are much cheaper but still effective. Collecting experience from all countries where Dry Rot is a problem will make it possible to formulate new ideas and possibly find new solutions. A questionaire has therefore been devised which it is hoped, members will complete and return in order that an accurate assessment of the present situation can be obtained.
A P Koch


Frequency of fungal decay in softwood windows in Germany
2010 - IRG/WP 10-10725
Knowing how often fungal decay occurs is a fundamental basis for general recommendations of preservative measures. To optimize the German recommendations for chemical wood preservation of windows made out of pine or spruce more than 2000 windows have been inspected. All windows had an opaque coating and were between 2 and 17 years old. The selection of the inspected windows was kept as randomly as possible. None of the windows had been previously checked for fungal decay. Approximately 0.5% of the windows in the first three floors showed visible fungal decay. Only windows oriented to the west where affected. Windows installed in the 10th to the 12th floor had a frequency of approximately 10% visible fungal decay. In these elevations the orientation of the window had no significant effect. The analysis of wood preservatives revealed that hardly any window have been treated in accordance with German standards. As the treatment of windows in Germany is still predominantly performed on frames after assembly the preservatives hardly penetrate into the critical areas of the corner joints.
D Lukowsky, O Moarcas, A Luette


High-frequency monitoring of mass loss due to brown rot degradation of modified wood
2016 - IRG/WP 16-10862
Fungi growing in liquid culture undergoes three separate phases in which they i) adapt to the new environment, ii) grow unrestrictedly and exponentially, and iii) are inhibited to increase in number/mass due to lack of nutrients etc. Filamentous fungi have been shown to exhibit similar growth phases in a solid food substrate and have been modelled to grow in this way also in solid wood. In modified wood with high treatment levels, fungi cause no or little mass loss but the reason for this has not been fully explained. To be able to predict the service-life of modified wood, understanding the growth pattern of wood degrading fungi in these materials may be important. The aim of this study was to find out whether brown rot fungi undergoes the same growth phases in solid wood as in liquid culture and study the growth pattern of brown rot fungi in modified wood. This was done through high-frequent monitoring of mass loss over 300 days of exposure of acetylated and furfurylated wood to Postia placenta. Mass loss results of the untreated wood indicated clearly that the fungi in this material go through phases similar to phases seen in liquid cultures. However, the results for the modified wood materials were less clear. Little mass loss and a degradation rate 100 times lower than in the untreated wood during exponential growth may suggest that the fungi in the modified wood samples were still adapting to the new environment. On the other hand, the fact that mass was lost at all suggests that degradation did occur and that the fungi were growing exponentially.
R Ringman, A Pilgård, K Richter


Analysis of hindgut bacterial phyla frequency and diversity in subterranean termites exposed to chitosan-treated wood
2017 - IRG/WP 17-10882
The termite hindgut contains a microbial community that symbiotically aids in digestion of lignocellulosic materials. For better understanding of the dynamics of the bacteria-termite relationship, a species survey of bacterial hindgut microbes in subterranean termites (Reticulitermes flavipes: Kollar) collected from Louisville, Mississippi was performed after exposure to chitosan-treated and control (water-treated) wood samples. Total genomic DNA was isolated from termite hindguts, amplified and 16S ribosomal RNA (rRNA) gene fragments were analyzed using next-generation sequencing techniques. Twenty-seven bacteria phyla were identified in both treatment groups, with six bacteria phyla showing significantly differences in abundance between the chitosan-treated and control groups. These results suggest that there was a treatment driven effect on the hindgut bacteria diversity.
O Raji, J D Tang, T Telmadarrehei, D Jeremic