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Termite-tunnels formation on the surface of termite-resistant wood species in field sites
2001 - IRG/WP 01-10400
In this report, termite-tunnels formation by the subterranean termite, Coptotermes formosanus Shiraki on the surface of termite-resistant wood species, namely, Hinoki (Chamaecyparis abtsu), Yoshino Hinoki (Chamaecyparis abtsu), Miyazaki Hinoki (Chamaecyparis abtsu), Hiba (Chamaecyparis abtsu) and Japanese cedar (Cryptomeria japonica) was conducted in field sites. Westernhemlock (Tsuga heterophylla), Douglas- fir (Pseudotsuga taxifolia) and Ryukyu pine (Pinus luchuensis) were used as the control. 62 The termite-resistant woods species were classified either as heartwood timber (H) or sapwood timber with a heartwood center (S) and also classified based on their prefecture of origin. Otherwise, the termite- resistant wood species for the termite test were examined in using the forms on the surface of all the termite-resistant wood species by the subterranean termite, Coptotermes formosanus Shiraki. It was found that even for termite-resistant wood species treatment with preservative chemicals is required.
Y Kadekaru, K Kinjo, S Yaga

Effects of pretreatments for the amelioration of preservative impregnability using the Oscillating pressure method (OPM)
1995 - IRG/WP 95-40044
For the purpose of an amelioration of preservative impregnability, three types of pretreatment: the steaming, the explosion and the boiling, were tested. The specimens were prepared by the domestic four species: Itajii, Ryukyumatsu, Sugi and Hinoki, and 1 refractry imported species: Douglas-fir. The dimension of specimens was 20 x 20 x 300 mm³ and were treated with CCA in a laboratory OPM machine. Three OPM schedules and Bethel process without after vacuume were tested in this experiment. The results obtained were follows: 1. In the case of the treatment of green woods, the calculated retentions of preservatives based on those initial mass, were periodically slowly increased or sometimes decreased. This reason was considered the replacement of the free water in wood to the preservative solution. The sapwood of rather easy treatable species like Ryukyumatsu, was obtained good penetration by Bethel process. The sapwoods of treatable species like Sugi and Hinoki, were obtained best penetration by OPM-1 or by OPM-2. The combination of the steaming and the OPM was rather good results for all species tested of green woods. 2. In the case of the treatment of the air-dried woods, the combination of the steaming and the OPM was obtained rather good results for all species tested included the refractry specimens like Douglas-fir.
K Suzuki, I Asaoka, S Tani, K Okada, T Hidaka

Effect of extractive fractions of Thuja plicata and Chamaecyparis nootkatensis heartwood on Coptotermes formosanus
2004 - IRG/WP 04-10535
Heartwood of some species has natural resistance to attack by termites due to the presence of toxic and/or repellent extractives, but the role of individual extractives in termite inhibition is poorly understood. Developing a better understanding of which extractives are most effective against termites may be useful for the identification of improved termite management strategies. The effect of selective extractive removal on termite resistance was assessed using matched samples of Thuja plicata (D.Don) and Chamaecyparis nootkatensis (D.Don) Spach heartwood. Samples were extracted using a variety of solvents and then exposed to Coptotermes formosanus Shiraki in a no-choice feeding test. The results suggest that the methanol-soluble extractives in Thuja plicata and Chamaecyparis nootkatensis play important roles in making the heartwood resistant to attack by Coptotermes formosanus. Volatile and hexane-soluble extractives were less important. Further analysis of specific extractive compounds are underway.
A Taylor, B L Gartner, J J Morrell, K Tsunoda

Effect of cyclic change of temperature on fungal growth and mass loss
1994 - IRG/WP 94-10065
For estimating the effect of cycling change of temparature on fungal growth, four Japanese species, sugi (Cryptomeria japonica), hinoki (Chamaecyparis obtusa), akamatsu (Pinus densiflora) and buna (Fagus crenata), four fungal species, Tyromyces palustris, Gloeophyllum trabeum, Coriolus versicolor, Pycnoporus coccineus, and five temperature conditions, 10, 20, 27, 35°C and cyclic temperature (20°C 12 hours and 30 or 27°C 12 hours) under constant humidity (75% RH) were examined. The results were summarised that the cyclic condition was rather high fungal growth rate in the case of majority of fungi tested but was not surely increased the mass loss of wood. This tendency is rather clear in the case of brown rot like Tyromyces palustris. The cyclic temperature conditions were not favorable to the groth of Serpula lacrymans.
K Suzuki, K Okada

Termite attack on susceptible lumber above naturally durable support posts
2000 - IRG/WP 00-10370
A multi-year field study was designed to simulate the use of naturally durable sill plates (dodai) and floor support posts in Japanese housing construction and test whether Formosan subterranean termites (Coptotermes formosanus) would tunnel over or through these resistant timbers to attack susceptible Japanese red pine (Pinus densiflora) lumber placed above them. This test was intended to explicitly address the possibility that a durable timber placed upon a solid concrete footing might create a sufficient barrier to subterranean termites to protect the structure from attack, in the absence of any other termite control specifications such as soil insecticide treatment. Inspection after three years in the field revealed that termites had damaged a Kiso Hinoki (Japanese cypress, Chamaecyparis obtusa) sapwood (with heart center) post, and a Hiba Arbor-vitae (Thujopsis dolabrata) sapwood (with heart center) floor post, although they had not reached the red pine block above each post. However, termites had also fully penetrated a Kiso Hinoki (Japanese cypress, Chamaecyparis obtusa) heartwood post, and severally damaged the red pine block on top of it. None of the durable woods in this test were damaged to the point where they would pose any sort of structural hazard. However, they clearly do not represent a barrier to further termite foraging, and there is also variation in durability among different samples of these durable woods. Sole use of termite-resistant sill plates or floor posts (as commonly required in both Japanese and American construction), in the absence of any other termite control measures, cannot be relied upon to protect the structure from termite penetration and damage to the adjoining susceptible wood framing.
J K Grace

Wood Aging. Characteristics of aged Hinoki wood from Japanese historical buildings
2012 - IRG/WP 12-40610
Wood has always played a major role in Japanese traditional culture. More than 90% of buildings listed as a National property or a nationally important cultural property of Japan are constructed with wood. In the ancient capitals Kyoto and Nara, many traditional wooden buildings were inscribed as World Cultural Heritage of the UNESCO. The most famous and the world’s oldest wooden construction still standing is Horyu-ji temple from the latter half of the seventh century. Wood is present in many cultural heritage objects thanks to its capacity to resist over long period of time. However, the evolution of its properties in regular use remains insufficiently known. The present study on the effect of wood aging takes advantage of the Japanese context where building traditions have been maintained for centuries. One major difficulty for the research on “aging of wood” is the gathering of suitable samples, with well-defined origin, certified dating and permission of publication by conservation administration. The Japanese context, where traditional uses of wood have been maintained for more than 1600 years, offers a unique opportunity to address the question of wood aging. Since 2004, the wood samples from various temples and other historical buildings were being gathered by the Research institute for Sustainable Humanosphere, Kyoto University, Japan. The matching of specimens from different origins is another typical obstacle. Wood is a variable material due to genetic variations and dependency on growing conditions of the trees. To discuss property changes due to aging, a recent reference is required. However, it is difficult and sometimes impossible to obtain recent wood that closely matches a given old wood sample. To overcome the difficulty, thermally treated wood as an accelerated aging can be used to produce corrections that will allow comparing data from slightly mismatched samples. Thermally treatment ware performed at 90, 120, 150, and 180℃ for various periods on new hinoki wood from Kiso area. This paper deals with mechanical characteristics of aged hinoki (Chamaecyparis obtuse Endl.) wood from Japanese historical buildings and thermally treated hinoki wood, especially their Young’s modulus, rapture energy and hygroscopisity. It is not only for the basic science study on aging of wood by using unique and indigenous Japanese hinoki wood, but also for the commonality and universality of worldwide wooden cultural assets. This research will have a positive role on preservation and conservation of wooden cultural properties in the world.
M Yokohama, S Kawai