几面表层漆黑的古铜镜之分析研究

AN ANALYSIS OF SEVERAL BRONZE MIRRORS WITH A BLACK SURFACE LAYER

序言表层漆黑的古铜镜,俗称"黑漆古"。这种铜镜,主要发现于战国至汉唐时的铜镜中,尤以战国至六朝的铜镜为盛。在地域上,主要见于湖南、湖北、安徽等地;北方的陕西、山西、山东、河南所见较少。在同一时期内,北方铜镜表面多呈灰白色,俗称"水银古"或"水银沁"。南方除去"黑漆古"外,有的镜子还呈绿黑色,俗称"绿漆古";有的为铅黑色、灰黑色,古谓"铅背"。"

This paper publishes a laboratorial analysis of 6 ancient bronde mirrors with a black surface layer, which belong in time to the period from the Warring States to the Six Dynasties, and 2 of them are unearthed from Changsha, Hunan Province and the rest 4 from Echeng, Hubei Province.The analysis aims to reveal the components of the alloy of the mirrors, their metallographic structure, the components, corrosion resistance and structure of the surface layer and the structure of the body. Up-to-date techniques and instruments are used for the analysis, including the atomic absorption spectrograph, electronic scanning microscope, Auger electronic microscope and metalloscope. The results obtained are listed in Tables 1—4. The main conclusions drawn from them are as follows:1. No matter whether the surface layers of bronze mirrors from the Warring States period to the Han and Tang Dynasties are black, greenish-black, grayish-black or grayish-white, they are all products of natural corrosion of the tin-plated surface and have nothing to do with artificiality.2. The surface colour of these bronze mirrors is mainly determined by the structural forms and percentage of the products of natural corrosion in the tin-plated surface layer.3. The tin in the surface layer of the black mirror came mainly from the plating material, the copper mainly from the mirror itself, and the lead may have come from both the plating material and the mirror. The iron, silicon, aluminum and phosphorus may have been just foreign matters that entered the mirror during the process of plating or by contamination through contact with earth.4. The surface brightness of black mirror must mainly be due to good polishing, though the structural forms of the material used for plating exert a certain effect.5. There is no obvious connection between the formation of the black colour on the surface of the bronze mirror on the one hand and the elements of the alloy and their metallographic structure on the other.