Study of biological deterioration in traditionally painted areas [of Kirishima Shrine]

Mold growing on areas painted oyster shell white
An on-site exposure test with a fungicide

 As part of a commissioned study on Development of Techniques to Prevent Color Paint Peeling at Kirishima Shrine and Work to Implement Those Techniques, the Center for Conservation Science and Restoration Techniques has studied biological deterioration of traditionally painted areas of Kirishima Shrine. Traditional painting techniques used organic substances such as animal glue and are usually susceptible to biological deterioration by microbes like mold. If mold grows, it can seriously mar a building’s appearance. Moreover, mold degrades the proteins in animal glue that serve as a binder, causing pigments to separate from the painted surface. Metabolites also cause pigments to discolor and dissolve. As a result, the physical deterioration of painted areas accelerates.
 Kirishima Shrine has suffered damage, i.e. extensive growth of mold, in areas that were painted traditionally with oyster shell white paint or ochre paint including walls of breezeways, the covered stone stairway, and the worship hall. This year, a microbiological study was conducted to identify the mold responsible and ascertain the impact of that mold on painted areas. Temperature and humidity changes on-site were also monitored and an exposure test with fungicides was also conducted to help devise optimal control measures.
 Environmental measurements revealed that the Shrine’s air temperature is lower than the air temperature of level ground and the Shrine has a relatively high relative humidity of about 70% as an annual average. The Shrine was found to have an environment conducive to the growth of indigenous microbes. During the on-site exposure test with fungicides, several agents were found to have fungicidal action, but some of the fungicides chemically reacted with the white paint and could lead to deterioration. One hundred and thirty-three fungal strains have been isolated from damaged areas. These strains were grouped based on colony morphology and analyzed phylogenetically and physiologically. Results indicated that 3 groups had highly prevalent fungal strains (i.e. they had the most strains isolated). These groups are presumed to play a major role in microbial deterioration of traditionally painted areas of Kirishima Shrine. Plans are to perform a more detailed analysis of the isolated strains and continue exploring measures to prevent and control microbial deterioration of areas with traditional oyster shell white paint and ochre paint in conjunction with exposure test results.

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