Complementary use of X-ray based imaging and analytical methods in the investigation of miniature portraits
Complementary use of X-ray based imaging and analytical methods in the investigation of miniature portraits
复制标题
基于 X 射线的成像和分析方法在微型肖像研究中的补充使用
DOI：
10.1016/j.microc.2019.104371
复制
发表时间：
2020
影响因子：
4.8
通讯作者：
P. Targowski
中科院分区：
文献类型：
--
作者：
J. Hradilová;D. Hradil;M. Pech;P. Bezdička;V. Neděla;E. Tihlaříková;P. Targowski
微型肖像仍然是很少研究的对象。其中一个原因是，细部的薄层和非常紧凑的绘画不允许任何采样。另一个限制是，非侵入性技术必须具有足够的空间分辨率，并且应该尽可能温和，因为任何表面变化都可能非常明显。通常，人像微缩的表面不涂清漆，这有利于分析，但同时也有较少的保护和较高的损坏风险。在这项工作中，三幅微型肖像代表了三个最重要的欧洲学派-英国，法国和奥地利-进行了调查。它们都可以追溯到19世纪初，都是用水彩画在象牙上的，这是1700年后最常见的支撑形式。已经测试了三种创新的分析方法：大面积x射线荧光测绘（MA-XRF）， x射线微衍射（micro-XRD）和环境扫描电子显微镜结合能量色散x射线微分析（ESEM-EDS）。在ESEM中对微细模型的EDS分析作为一种全新的分析方法进行了测试，在样品室中使用水蒸气代替氮气。当有效地结合上述方法时，部分复绘和修饰或后来添加的签名已被描述和定位。锌白的早期使用（大约1800年），缺镍钴蓝的可能来源，以及As颜料降解导致次生砷酸盐形成的许多表现都已得到证实。
Miniature portraits are still little studied objects. One reason is that thin layers of detailed and very compact paintings do not allow any sampling. Another limitation is that non-invasive techniques must have sufficient spatial resolution and should be as gentle as possible as any surface change can be very noticeable. Usually, the surface of portrait miniatures is not coated with varnish, which is advantageous for the analysis, but at the same time there is a less protection and a higher risk of damage. In this work, three miniature portraits representing the three most important European schools - English, French and Austrian - have been investigated. They are all dated to the beginning of the 19th century, all painted in watercolour on ivory, which is the most common type of the support after 1700. Three innovative analytical approaches have been tested: large area X-ray fluorescence mapping (MA-XRF), X-ray micro-diffraction (micro-XRD) and environmental scanning electron microscopy coupled with energy dispersive X-ray microanalysis (ESEM-EDS). EDS analysis of miniatures in ESEM was tested as an entirely new analytical procedure with using water vapour instead of nitrogen in the specimen chamber. When effectively combining the above-mentioned methods, partial overpaintings and retouchings or a later added signature have been described and localized. A very early use of zinc white (around 1800), a possible origin of Ni-depleted cobalt blue, and numerous manifestations of degradation of As pigments that led to the formation of secondary arsenates have been demonstrated.