Al-Emam Ehab, Beltran Victoria, De Meyer Steven, Nuyts Gert, Wetemans Vera, De Wael Karolien, Caen Joost, Janssens Koen
Department of Conservation, Faculty of Archaeology, Sohag University, 82524 Sohag, Egypt.
AXES, Faculty of Science, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
Polymers (Basel). 2021 Aug 10;13(16):2651. doi: 10.3390/polym13162651.
Polymeric materials have been used by painting conservator-restorers as consolidants and/or varnishes for wall paintings. The application of these materials is carried out when confronting loose paint layers or as a protective coating. However, these materials deteriorate and cause physiochemical alterations to the treated surface. In the past, the monumental neo-gothic wall painting 'The Last Judgment' in the chapel of Sint-Jan Berchmanscollege in Antwerp, Belgium was treated with a synthetic polymeric material. This varnish deteriorated significantly and turned brown, obscuring the paint layers. Given also that the varnish was applied to some parts of the wall painting and did not cover the entire surface, it was necessary to remove it in order to restore the original appearance of the wall painting. Previous attempts carried out by conservator-restorers made use of traditional cleaning methods, which led to damage of the fragile paint layers. Therefore, gel cleaning was proposed as a less invasive and more controllable method for gently softening and removing the varnish. The work started by identifying the paint stratigraphy and the deteriorated varnish via optical microscopy (OM), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy. A polyvinyl alcohol-borax/agarose (PVA-B/AG) hydrogel loaded with a number of solvents/solvent mixtures was employed in a series of tests to select the most suitable hydrogel composite. By means of the hydrogel composite loaded with 10% propylene carbonate, it was possible to safely remove the brown varnish layer. The results were verified by visual examinations (under visible light 'VIS' and ultraviolet light 'UV') as well as OM and FTIR spectroscopy.
聚合物材料已被壁画修复师用作壁画的加固剂和/或清漆。当遇到松散的漆层时或作为保护涂层时，就会应用这些材料。然而，这些材料会变质并导致被处理表面发生物理化学变化。过去，比利时安特卫普圣扬·贝奇曼斯学院小教堂内的新哥特式纪念性壁画《最后的审判》用一种合成聚合物材料进行了处理。这种清漆严重变质并变成褐色，遮挡了漆层。又因为清漆只涂在了壁画的部分区域，没有覆盖整个表面，所以有必要将其去除以恢复壁画的原貌。修复师之前尝试使用传统清洁方法，结果导致脆弱的漆层受损。因此，凝胶清洁被提议作为一种侵入性较小且更可控的方法，用于轻柔地软化和去除清漆。这项工作首先通过光学显微镜（OM）、扫描电子显微镜结合能量色散X射线光谱仪（SEM - EDX）、X射线衍射（XRD）和傅里叶变换红外（FTIR）光谱仪来确定漆层结构和变质的清漆。在一系列测试中使用了负载多种溶剂/溶剂混合物的聚乙烯醇 - 硼砂/琼脂糖（PVA - B/AG）水凝胶，以选择最合适的水凝胶复合材料。借助负载10%碳酸丙烯酯的水凝胶复合材料，能够安全地去除褐色清漆层。通过目视检查（在可见光“VIS”和紫外光“UV”下）以及OM和FTIR光谱仪对结果进行了验证。
