Wood samples treated with metallic naphthenates were evaluated for their leachability, water absorption and hygroscopicity. Permeability of the chemicals into wood was also compared among three wood species.
Copper naphthenate showed a high resistance to leaching. Zinc naphthenate was inferior to copper naphthenate in leachability, especially at lower concentration.
Water absorption varied with wood species, although no conspicuous difference was found between the two test chemicals. Concerning the ratio of water absorption between treated and untreated woods, the highest value was recorded by Pinus densiflora and followed by Fagus crenata and Cryptomeria japonica. In the comparison of hygroscopic ratio, P. densiflora was the highest and followed by C. japonica and F. crenata.
Copper naphthenate afforded the treated wood, have nothing to do with concentration 0.5-0.8 as hygroscopic ratios. Chemicals were easily permeated into P. densiflora. However, penatration of the chemicals into C. japonica and F. crenata was restricted only to the surface layers of wood. Apart from the effect of wood species, viscosity of the chemicals, which is changeable with concentrations, appeared to influence the permeability.

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Ise Jingu consists of many shrines having a thatched roof with Japanese pampas grass (Kaya: Miscanthus sinensis) and is rebuilt at regular intervals of 20years. The rebuilding needs an enormous quantity of Kaya, so Kaya must be stored for a long period. Sometimes, the severe damage by insect pests take place in Kaya during the storage.
We examined the damage of stored Kaya in Jingu. Two insects appeared from the stems of damaged Kaya. One was the dead body of Anadastus praeustus. Another was Dinoderus minutus, which appeared as an alive grub or adult. D. minutus ate the cortex and pith except epidermis of stem. The damage occurred at about 60cm in length from the cut end of stem. D. minutus is an important pest of bamboo and takes nutrients from the hot water extractive of bamboo as well known. Therefore, we analyzed the extractive contents of stored Kaya. There was no notable difference in the extractive contents between the damaged and undamaged Kaya in same storage house. From these results, it was expected to enlarge the damage by the insect. So, we treated Kaya for the prevent of damage with the fumigation and spray of pest control chemicals.

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