大同华严寺辽代彩绘泥塑颜料与胶结剂的科学剖析

Scientific analysis of pigments and adhesives of polychrome clay sculptures of the Liao Dynasty in Huayan Temple in Datong

为揭示大同辽代华严寺彩绘泥塑颜料及胶结剂的化学成分及调制应用组合,对华严寺薄伽教藏殿内的典型颜料层样品进行了综合剖析。利用超景深显微镜、扫描电镜-X射线能谱、显微拉曼光谱等对彩绘样品中的颜料部分展开分析。结果表明,红色颜料主要是铅丹(Pb_(3)O_(4))和朱砂(HgS),绿色颜料主要是孔雀石[Cu_(2)CO_(3)(OH)_(2)]和氯铜矿[Cu_(2)(OH)_(3)Cl],而且这两种颜色存在着同色系的两种颜料混和使用的情况。蓝色颜料则为蓝铜矿[Cu_(3)(CO_(3))_(2)(OH)_(2)],黄色颜料为雌黄(As_(2)S_(3)),金色区域则主要是由金(Au)构成;采用红外光谱和甲基衍生化-热裂解-气相色谱串联质谱技术对彩绘样品中的胶结剂成分进行检测。结果表明,金色区域的胶结剂主要是熟桐油和胶蛋白,说明其中存在着“金胶油”的传统贴金工艺;而其他红、绿、蓝、黄等彩色区域则只有胶蛋白为胶结剂。研究结果为后续的彩塑保护提供一定的科学支持。

In order to reveal the compositions of pigments and adhesives used for polychrome clay sculptures of the Liao Dynasty in Huayan Temple in Datong,we carried out comprehensive analysis of typical polychrome samples.Digital microscopy,scanning electron microscopy-energy dispersive spectrometry(SEM-EDS)and micro-Raman spectrometry were used for pigment analysis.The results show that the red pigments are mainly lead red(Pb_(3)O_(4))and cinnabar(HgS),the green ones mainly malachite[Cu_(2)CO_(3)(OH)_(2)]and atacamite[Cu_(2)(OH)_(3)Cl](these two samples were mixed with two different pigments in similar colors),the blue one is azurite[Cu_(3)(CO_(3))_(2)(OH)_(2)],the yellow one orpiment(As_(2)S_(3))and the gold area mainly composed of gold(Au).The composition of adhesives in polychrome samples was detected by Fourier transform infrared(FTIR)spectrometry and thermally assisted hydrolysis and methylation-pyrolysis-gas chromatography/mass spectrometry(THM-Py-GC/MS).The results show that the main adhesives for the gold area are heat-bodied tung oil and glue protein,indicating the existence of the traditional painting technique of“gilding”.For the other color(red,green,blue and yellow)areas,only glue protein is used as adhesives.