Chemical analyses of the Chinese mirror-molds of the Han-Period and restoration experiments of the high-Sn bronze mirror

镜面模具表面常可见一层黑色外壳。通过化学分析，证实了黑色结壳中存在来源于铸造金属的Cu、Sn、Pb、Zn等元素，认为黑色结壳是铸造过程中镜模与金属的反应产物。此外，还发现了S和C，这表明它们可能来源于模具的涂层或脱模剂。然后，以几种油脂作为包覆剂或分离剂，对铜、锡、铅的混合物进行了铸造试验。用脂肪作脱模剂可以很好地再现黑色外壳。通过对再现的黑色外壳的化学分析，证实了镜面模具表面外壳中金属元素和S的存在。未对C元素进行分析，认为C是铸造过程中脂肪燃烧产生的一种烟尘。

A black crust is often observed on the surface of the mirror-mold. As a result of the chemical analyses, the elements such as Cu, Sn, Pb, and Zn originated in the casting metals were confirmed to exist in the black crust The black crust is, therefore, thought to be a reaction product of mirror-mold and the metal in the course of the casting process. In addition, S and C were found and it indicates that they might be originated in the coating- or release-agents for the mold. Then, the casting experiments were carried out by the mixture of Cu, Sn, and Pb using several kinds of oil and fat as the coating- or separating-agents. A black crust was well reproduced by using a fat as release-agent. As a result of chemical analyses of the reproduced black crust, the existence of metallic elements and S were confirmed to be in the crust on the surface of the mirror mold. The element of C was not analyzed but C was thought to be a kind of soot caused from burned fats in the course of casting.