Research on the dynamic characteristics of moisture absorption and desorption of the wall painting plaster of tomb murals

The dynamic characteristics of moisture absorption and desorption of the ground support layer of the tomb mural were studied. Through the design of the moisture absorption and desorption test, the moisture absorption and desorption process of the simulated ground support test block was monitored and the corresponding dynamic curve of moisture absorption and desorption was drawn. The model was used to fit the dynamic curve of moisture absorption and desorption of the test block. The research results show that the moisture absorption and desorption process of the ground support layer of the tomb mural shows the characteristics of first fast and then slow, and the moisture absorption period and dehumidification period in the early stage of the moisture absorption and desorption process are significantly shorter than the saturation period and stability period in the late stage of the moisture absorption and desorption process. The moisture content of the test block after the moisture absorption and desorption process is higher than the initial moisture content of the test block, that is, some water remains in the ground support layer of the mural. The moisture absorption dynamic curve and moisture release dynamic curve of the simulated plaster test block respectively conform to the double exponential model and the first-order exponential model, R² >0.988, and the fitting effect is good.