湿度是铅丹变色的主要因素  

Humidity Is the Main Cause for Discoloration of Minium

作　　者：盛芬玲[1] 李最雄[2] 樊再轩[2] 

机构地区：[1]兰州大学分析测试中心 [2]敦煌研究院保护研究所

出　　处：《敦煌研究》1990年第4期104-119,128-129,共18页Dunhuang Research

摘　　要：为研究壁画颜料变色的原因,揭示它的变色规律,国内外科学工作者长期以来,进行了广泛地观测和研究。我们通过对敦煌莫高窟十一个朝代四十四个洞窟中的二百多个壁画颜料样品的分析发现,铅丹、朱砂和土红三种红色颜料中,使用最普遍的是铅丹,而变色最严重的也是铅丹。分析的三十八个红色颜料中,含Pb₃O₄式样十四个,占37%;棕黑色颜料试样三十三个,其中含Pb2或PbO₂和Pb₃O₄共存的试样三十二个,占97%。实验中,我们又对莫高窟壁画的变色做了一次现场调查,并对几个变色典型的洞窟壁画颜料做了色度测定。在莫高窟壁画中,Pb₃O₄的变色确实是一种极其严重的病害。上述分析的三十三个棕黑色颜料试样中,成份是PbO₂的十八个,除主要成份是PbO₂外,还含有少量Pb₃O₄的十四个,这不但说明Pb₃O₄的变色十分严重。The experiments were carried out to see the effect of moisture and light on the discoloration of red lead, hematite, vermilion and white lead. Hematite were proved to be a kind of stable pigment, those two factors can't make it discolor in normal condition. Although at a high humidity, its surfance is easilywetted, resulting in its color becoming dark. but recover when dry. White lead is also a kind of rather. stable pigment. Under normal condition. various humidities and visible light can not make it significantly change, I Ilumination can make vermilion evidently darkened but the humidity can not affect the process of its darkening.Some very important facts have been found from the experiment, at RH below 70%, the discoloration of red lead occurred very little, but at and above RH 70%, the fluorescent light, could greatly promote the discoloration of red lead. Consequently it can be concluded that RH 70% can he defined as the lower limit of RH for discoloration of red lead. This conclusion is very important for conservvation of Dunhuang wall painrings.

关 键 词：壁画颜料 莫高窟壁画 铅丹 敦煌莫高窟 红色颜料 黑色颜料 朱砂 炳灵寺 变色规律 相对湿度 

分 类 号：K870.6[历史地理—考古学及博物馆学]