Applications of Spectral Analysis Methods in the Restorationand Preservation of Some Easel Paintings fromRomanian Museum Collections

摘要

In this study the analysis of the painting medium (vegetable oil based binder) from nine canvas paintings, belonging to the national cultural heritage is presented. The paintings were investigated and restored in the Brukenthal National Museum, Sibiu laboratories. Seven paintings belong to the Brukenthal Painting Galleries and two artworks belong to other collections. The nine artworks are painted in oil or mixed oil-tempera techniques and date from late 15~(th) century to first half of 20th century. The investigated canvas paintings required urgent restoration. Due to the fact that the restoration techniques and materials are greatly influenced by the nature of the binders found in the painting layers, a number of 15 microsamples (around 1 mg) were carefully collected. In order to identify the nature of the binders, these samples were then analyzed using nuclear magnetic resonance (NMR), gas chromatography coupled with mass spectroscopy (GC-MS) and Fourier transformed infrared spectroscopy (FT-IR). We aimed to confirm the presence of linseed oil in the investigated artworks. To this end, we focused on the identification of saturated fatty acids biomarkers, as these substances are not directly involved in the polymerization processes. The biomarkers were evidenced as methyl esters by GC-MS, the most accessible analysis for their detection. The method presented herein allows the analysis of the palmitic and stearic acids methyl esters, found in the old paintings microsamples. It was thus possible to identify the presence of siccativated linseed oil in 13 out of the 15 investigated samples. The results confirmed the proposed painting technique and allowed the correct choice of compatible restoration materials and methods.