新疆阿斯塔那唐墓出土彩塑的制作工艺和颜料分析

新疆阿斯塔那古墓群出土了大量的彩塑,为了解其制作工艺与彩绘颜料成分,采用显微激光拉曼光谱,结合剖面观察和能量色散X射线荧光光谱等科技手段,对出土于唐墓的6个样品进行了分析鉴定.结果表明,泥胎表面先用硬石膏做打底层,再施以彩绘,且彩绘颜料厚薄有异.所使用的红、黄、黑、白和绿色颜料有铅丹、密陀僧、朱砂和土红、雌黄、炭黑、硬石膏及氯铜矿等无机颜料,而粉色彩绘是由铅丹(或铅丹和密陀僧的混合物)与硬石膏调和而成,且密陀僧作为彩绘颜料在新疆是较早的发现.其最为重要的发现是蓝色彩绘为植物性染料——靛蓝.这一研究结果,为进一步的彩塑修复与保护方案的制订提供了有价值参考.

Analysis of techniques and pigments used for colored clay sculptures excavated from the Tang Tomb at Astana, Xinjiang

The Astana graveyard is located in the Gobi Desert in the Turpan basin, Xinjiang, China, and is believed to have been the public cemetery for ancient Gaochang Country dating to a period between the WesternJin and the midTang Dynasty. Large amounts of clay sculptures with multicolored painted patterns, including warriors, horses, tigers, etc, have been unearthed from the graveyard. In order to illuminate the pigments and techniques used for the polychrome on the clay sculptures, micro-Raman spectroscopy analysis along with microscopy observation and EDXRF were used to analyze six clay figure shards selected from a Tang Dynasty tomb dated to A.D. 687~745. Crosssectional observation revealed that the thickness of the pigment layer among samples varied and that in one case the white ground underlayer was anhydrite, which suggested the influence of mural painting tradition. Some pigments were identified, including red/orange (cinnabar, red lead or massicot), brown (haematite), yellow (orpiment), black (carbon black), white (anhydrite), green (atacamite) and pink (anhydrite+red lead or anhydrite+massicot/red lead). This appears to be the earlier report of the use of massicot as a pigment in Xinjiang. Furthermore, the blue pigment was identified as indigo, which is an essential discovery. These identified pigments reflect the diversity and complex palette of ancient peoples. The investigation of pigments and ground layers will provide reference for the restoration and conservation of these precious artworks.