The Mogao Grottoes site at Dunhuang is famous for its wonderful wall paintings. Though natural fabrics added to the plaster can improve its strength, at present, little research has been done to understand the shrinkage properties of adding fabric. In this research, a paraffin oil method was used to measure the soil shrinkage characteristic curve(SSCC) of plasters mixed with different natural fabrics such as wheat, straw, and hemp.The SSCC test results indicate that as long as the type of natural fabric remains unchanged, when the amount of fabric increases the shrinkage limit of the silt soil will gradually increase while the volumetric shrinkage will gradually decrease. As our analysis indicates, the use of natural fabrics has increased the frictional resistance between the fabric and soil particles and partially counteracted the capillary force, thus controlling the shrinkage deformation of the soil. This means that ancient craftsmen knew how to improve the strength and control the shrinkage deformation of murals by adding natural fabrics to the silt soil for making mural plasters.
