Assessing the deterioration risk of mural paintings in Cave 98 of Mogao Grottoes based on the hygrothermal behavior

Abstract

Cave 98 is a typical cave in Mogao Grottos with various and serious degradations. This paper aims to clarify the heat and moisture transfer law of Cave 98 and murals and evaluate whether the current hygrothermal environment is conducive to the long-term preservation of murals. In this paper, a coupled heat and moisture transfer 2D model of Cave 98 was first established, and the accuracy of the model was verified by on-site monitoring data. Then, the spatial distributions of the temperature and moisture in Cave 98 were analyzed, and the quantitative evaluation of the deterioration risk of mural paintings in different locations was further evaluated. The results showed that 14% and 13.8% of the time indoor temperature and relative humidity (RH) exceeded the target range. Salt damage occurred more than 10 days a year, mold contamination occurred just a few days a year, and deterioration occurred at its peak in summer. Dehumidification measures can be taken during periods of high humidity to improve the adaptability of the current preservation environment.