Abstract
In storerooms without air-conditioning or dehumidification systems, fungi tend to grow in summer, when the outdoor relative humidity is high enough for fungal growth in Japan. For the conservation of cultural assets in these storerooms, vapor-impermeable bags might be useful as containers. Nine kinds of test bags, which were heat-sealable, were prepared from different membrane materials commercially available. A fungal detector, that encapsulates spores of sensor fungi and nutrients, was put in each test bag and sealed up using a heat sealer for determination of a fungal index, which represents the environmental (climate) potential for fungal growth. Then, the test bag encapsulating the detector was exposed under a humid climate in a moisture chambers set at 25°C and 93.6% relative humidity. Fungal index was measured for evaluation of microclimates inside of each test bag after exposure of 2, 7, 14, 28, 56 or 182 days. The microclimates in the bags differed depending on the employed membrane materials. No growth of sensor fungi was observed even in 182-days exposure in the sealed bags of aluminum-laminated film (0.114 and 0.092 mm in thickness), and the fungal index values were less than 0.3. In contrast, the growth of sensor fungi was observed in 2-days exposure in the bag of polyethylene film (0.010 mm in thickness), and the fungal index value was more than 80. For this reason, the bag made of aluminum-laminated film is considered to be very useful for the conservation of cultural assets in the humid storerooms aforesaid. Fungal index must be a useful tool in the operation of IPM (Integrated Pest Management) at museums, libraries, and other buildings.
