청동거울 석제거푸집의 복원 제작기술과 주조 실험

Abstract

In this research, the experimental results of recreating bronze mirrors cast using different talc casts based on the rough linear patterned bronze mirrors excavated at Yeoui-dong, JeonJu; Dasong-ri, Iksan and Goejeong-dong, Daejeon were analyzed. The most commonly used Bronze age material, talc was used to make the casts. Also, cast manufacturing tools such as a chisel, axe and awl used in this experiment were a recreation of Bronze Age tools that is thought to have been used for the same purpose. The recreated tools were based on the tool marks on the stone cast excavated at YeongArm, Jeonnam. High quality talc with smooth surface afforded ease for detailed carving. The carving process became arduous when there were impurities and fine internal cracks in talc. From the observation made on the stone cast after experimental casting, one could see the Yeoui-dong, JeonJu cast made with impure and fine hair line cracked talc was prone to splitting and the end product lacked fine details compared to the product from a high quality talc cast. The splitting and loss of split areas were also observed on the Dasong-ri, Iksan cast made with low quality talc. In comparison, the Goejeong-dong, Daejeon cast made with high quality talc was robust even after it was used to cast twice. Thus, it could withstand multiple casting When approximately 2/3 of a casts’ surrounding was filled with dirt then bronze melted at 640 ℃ was poured into the cast, the area filled with dirt had smooth surface and obtained detailed pattern, in contrast the exposed area had rough surface and failed to take fine detail. This is contributed to a molten metal seeping up to the inlet of the cast from different metal hardening rate due to different cooling time (510℃) as part of the cast was exposed to surrounding air. The surface finishing process was conducted when the cast bronze mirror became soft after annealing step. The inlet cast was easily removed using a bronze axe. Also, to increase its reflectance, the mirror was polished using whetstone, san and wood ash in sequence. The results of this research on 1) Restoration of the talc cast using contemporary tools, 2) Effect of talc quality on its end product, 3) Difference on surface finish depending on the different cooling rate will provide valuable data for understanding casting process and manufacturing process of Bronze Age cast.