独乐寺观音阁辽代十一面观音像的材质分析

独乐寺观音阁内十一面观音像保存至今,泥胎存在裂隙、空鼓、脱落等病害。利用超景深三维显微镜、X射线衍射分析(XRD)、激光粒度分布仪等对观音像泥胎进行了材质分析。通过控制砂、纤维含量,分析泥塑试样的收缩性,并探索纤维含量对泥胎收缩性的影响规律。结果表明:观音像泥胎的制作原料取自当地,其中土颗粒粒径多在5~70 μm之间,约占总量的79.5%；主要矿物成分为石英和伊利石,还有部分钠长石和钾长石,以及少量的高岭石。粗泥层含砂量约为35%,麦草(麦秆及麦壳混合物)含量约6%~9%,长度大多在2 cm以下；细泥层含砂量约为30%,麻丝含量约2.1%,长度大多集中在2 cm。麦草和麻丝的加入对泥胎的收缩均能起到抑制作用。随着麦草含量的增加,抑制作用呈现先增大后减小的趋势,掺和6%的麦草抑制作用最好；添加麻丝可使试样的最终线缩率显著减小,但麻丝的多少对线缩率的减小幅度影响不大。观音像泥胎的原纤维配比就有很好的抑制收缩效果。本次研究获得了十一面观音像泥胎的材料组成信息,得出了纤维占比对泥胎收缩性的影响,为十一面观音像的修复与保护提供了参考。

Material analysis of the Liao Dynasty Eleven-faced Avalokitesvara statue in Guanyin Pavilion of Dule Temple

The Statue of Eleven-faced Avalokitesvara in Guanyin Pavilion of Dule Temple has been preserved to the present day, but there are some diseases such as cracking, hollowing and falling off. The materials for the statue core were investigated using ultra depth-of-field 3D microscopy, X-ray diffraction and laser particle size distribution analysis. The contractility of clay samples was analyzed by controlling the contents of sand and fiber, and the effect of fiber content on the contractility of clay was explored. The results show that the raw materials for the statue core were taken from the local area, and the size of clay particles was mostly between 5 μm and 70 μm (accounting for about 79.5% of the total). The main mineral components were quartz and illite, with some albite and potassium feldspar and a small amount of kaolinite existing. For the coarse mud layer, the sand content was about 35%, the wheatgrass (a mixture of wheat straw and husk) content was about 6%-9%, and the length was mostly below 2 cm. For the fine mud layer, the sand content was about 30%, the hemp content was about 2.1%, and the length was mostly concentrated at 2 cm. The addition of wheat straw and hemp could inhibit the contraction of mud. With the increase of wheat grass content, the inhibitory effect increased first and then decreased, with the addition of 6% wheat grass boasting the best inhibitory effect. The final shrinkage rate of the sample could be significantly reduced by adding hemp, but the amount of hemp had little effect on the reduction rate. The fiber ratio of the statue core had a good effect of inhibiting contraction. In this study, material composition information of the core of the Eleven-faced Avalokitesvara statue was obtained, and as was the influence of fiber ratio on the contraction of the statue core. This work provides a reference for the restoration and conservation of the statue.