汉代铸钱夹砂陶背范的分析研究

与汉代铸钱相关的遗物中,铸钱夹砂陶背范出土数量最多,是由泥质面层与夹砂背层组成。为了揭示铸钱夹砂陶背范的制作工艺并探讨陶范多次使用的可能性及夹砂层的作用,对陕西西安窝头寨汉代铸钱遗址出土的铸钱夹砂陶背范进行分析研究。结果表明,泥质面层采用细泥料制作,其作用是保证所铸造的金属钱币具有优良的表面质量；夹砂背层是在制范泥料中掺杂了较多的肉眼可见的砂砾,其作用是提高陶范的机械性能,减小陶范受热后的变形,有利于它与金属范合范铸钱。铸钱夹砂陶背范的制作过程是:先制作夹砂层,然后在夹砂层上制作细泥层,在细泥层上印制钱币的背郭型腔,与金属范组成铸型铸造钱币。证实夹砂层可以重复使用,当泥质面层损坏后可以除掉表面的细泥层或直接在原型腔面上另加一层细泥重新制作背郭型腔,再次进行钱币的铸造,夹砂层可以一直使用到被损坏为止,从而极大地提高了铸钱效率。

Study of the clay-gravel molds for bunch-casting used in minting techniques of the Han Dynasty

Among the relics related to the coin casting of the Han Dynasty, the quantity of the clay-gravel molds is the largest. These consist of a clay surface layer and a clay backing layer mixed with much gravel. The surface layer was made from clay and plant ash to improve the quality of coins. The backing layer was made of clay and gravel to improve its mechanical properties and decrease the deformation of mold after firing. The production process was as follows:first, a backing layer was made of clay and gravel; second, a thin fine clay layer was made on the back as a surface layer; then the back pattern cavities of coins were made on the fine clay layer using a model. After being used for casting metal coins, the surface layer would be damaged by molten metal. A new thin layer could be made directly on the underlying surface or after the removal of the previous surface layer. The backing layer could be used many times until it broke. As a result, the production efficiency for casting bronze coins was improved.