Removal of a Past Varnish Treatment from a 19th-Century Belgian Wall Painting by Means of a Solvent-Loaded Double Network Hydrogel

Polymers

Joost Caen¹  Vera Wetemans¹  Victoria Beltran²  Gert Nuyts²  Koen Janssens²  Steven De Meyer²  Karolien De Wael²  Ehab Al-Emam³ 

[1] ARCHES, Faculty of Design Sciences, University of Antwerp, Mutsaardstraat 31, 2000 Antwerp, Belgium;AXES, Faculty of Science, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium;Department of Conservation, Faculty of Archaeology, Sohag University, 82524 Sohag, Egypt;

关键词: FTIR spectroscopy;    gel cleaning;    optical microscopy;    SEM-EDX;    solvent-loaded hydrogels;    deteriorated synthetic varnish;   

DOI  :  10.3390/polym13162651

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown