2nd Workshop on “Humidity-controlled Warm-air Treatment”
The 2nd workshop for specialists on the new insecticidal treatment for historical wooden buildings, known as “humidity-controlled warm-air treatment,” was held on May 9th, 2019.
Pest-borne damage to historical wooden buildings risks not only the loss of important wooden materials but also building safety, as the wooden materials can become hollow, thus weakening the strength of the lumber construction material and the building itself. In response to severe pest-borne damage, the Rinno-Ji Temple at Nikko has undergone closure and repair. Fumigation with sulfuryl fluoride gas, which is known to have almost no effect on cultural properties, was performed to eradicate all noxious pests in the building. However, there are huge health and safety risks associated with the use of mass fumigation with poisonous chemical substances, and such treatment can also dissuade neighboring institutions from opening to the public.
To address this issue, humidity-controlled warm-air treatment was developed as a new insecticidal treatment. This method eliminates pests by increasing the temperature to 60 degrees Celsius while regulating the humidity without altering the water content of the wood, thus minimizing any damage to the wooden content. Two successful domestic cases have been reported with no significant damage found in buildings containing Urushi (Japanese lacquer) decorations. Subsequent examination of these cases indicates that the technology used in this new treatment is nearly ideal. Nevertheless, concerns have been raised regarding the number of technicians required and the cost involved, which must be addressed before formally establishing humidity-controlled warm-air treatment as a valid insecticidal treatment. Also, since this a newly developed treatment, its long-term performance is difficult to evaluate; there may be as yet unknown effects inherent in the use of this treatment.
Several issues must be resolved before humidity-controlled warm-air treatment can be considered to be an established insecticidal treatment method. We look forward to working over the long-term in cooperation with related organizations.