Study On The Performance Of Ancient Sculpture Clay In Qinglian Temple Of Jincheng City In Shanxi Province

Qinglian Temple is located in Jincheng City, Shanxi Province, which has preserved more than sixty clay sculptures made during the period from the end of Tang and the beginning of Song Dynasty to Ming and Qing Dynasty. These clay sculptures have an extremely high value. The study on performance of sculpture clay in Qinglian Temple, which deepens the recognition of materials and the process of ancient clay sculptures, provides a reference for the conservation of ancient clay sculptures.The result about the composition analysis of sculpture clay shows that straw was added to the crude layer and cotton was added to the thin layer. The fiber content of the crude layer is larger than that of the thin layer. In the microstructure, straw is mostly striped sheet with thicker diameter, and cotton is curly ribbon with thinner diameter. The material of clay sculpture was divided into yellow soil and red soil. Compared with the yellow soil, the red soil has more crude size particles and quartz, but less calcite, kaolinite and chlorite. Using the ratio of chemical element content, Al/Ca and Fe/Ca, can also distinguish these two kinds of soil. When using red soil to sculpt, it will usually be sieved, and thin layer was mixed with a certain amount of sand. When it comes to yellow soil, the soil will usually be mixed with some sand, and the incorporation of crude layer was greater than thin layer. The microstructure of the thin layer is intensive cemented sheet, while the crude layer is mosaic cemented sheet-granule. This difference of microstructure is related to the process of beating and extruding. The content of SO42- and Ca2+ in solube salt of sculpture clay is higher than the natural soil, which correlates with the high hardness and sulfate content of the local water quality. It may be quite significant for the performance and preservation of these ancient clay sculptures.The result about the performance simulation of sculpture clay shows:with the increase of the content of crude size particles, the strength and contractility of red soil improved while the plasticity decreased, and the plasticity of yellow soil decreased too. With the increase of the proportion of kaolinite in clay mineral, the plasticity of red soil decreased, while the strength improved first and then decreased. Adding fiber will improve the plasticity of sculpture clay, and the effect of cotton is slightly better than straw. The plasticity and strength of red soil are better than those of yellow soil, while the contractility is conversed. The different performances between red soil and yellow soil depend on the content of crude size particles and the proportion of kaolinite in clay mineral.The materials of sculpture clay in Qinglian Temple consist of soil, sand, fiber and water with micro-soluble salt, while the process includes sieving, mixing sand, adding fiber, beating and extruding. Through the study on literature and sculpture clay in Qinglian Temple, the horizon of ancient sculpture clay should be rough layer-lined layer-middle layer-thin layer, and the performance requirement, materials and process of each layer are different.