Ehab Al-Emam,1,2,* Victoria Beltran,2 Steven De Meyer,2 Gert Nuyts,2 Vera Wetemans,3 Karolien De Wael,2 Joost Caen,3 and Koen Janssens2


1Department of Conservation, Faculty of Archaeology, Sohag University, 82524 Sohag, Egypt
2AXES, Faculty of Science, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium; [email protected] (V.B.); [email protected] (S.D.M.); [email protected] (G.N.); [email protected] (K.D.W.); [email protected] (K.J.)
3ARCHES, Faculty of Design Sciences, University of Antwerp, Mutsaardstraat 31, 2000 Antwerp, Belgium; [email protected] (V.W.); [email protected] (J.C.)
*Correspondence: [email protected]_bahe or [email protected]


Materials Science


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.



For the examination of the cross-sections of the paint samples, a Nikon ECLIPSE LV100ND microscope attached to a CoolLED pE-4000 UV light source and equipped with a Nikon DS-Fi3 camera (Nikon, Leuven, Belgium) was used (Figure 2 and Supplementary Figure S2).

Product Associated Features

The pE-4000 Universal Illumination System offers 16 selectable wavelengths from 365 - 770 nm, making it a highly flexible illuminator covering a wide variety of fluorophores

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