Discovery of Vespasiano Bignami paintings at the National Theatre of Costa Rica through technical photography and UV–Vis spectroscopy

AbstractEstablishing and understanding large format paintings are key to provide accurate information about the artist’s palette and developing conservation strategies. Therefore, investigating the artworks of a population offers insight into its culture, history and origins which reveals individual and collective identity through cultural heritage worldwide. Particularly, the ceiling of the Foyer at the National Theatre of Costa Rica (Central America) is decorated with three large format paintings from the nineteenth century made by the Italian painter Vespasiano Bignami. The paintings are known as La Poesía, La Música and La Danza (The Poetry, the Music and The Dance) and have undergone restorations in the past. However, their state of conservation is unknown and thus demands accurate scientific examination in order to document their status and the extent of undocumented previous restoration work. To overcome those issues, we propose the application of a combination of non-invasive and in-situ techniques to carry out a qualitative assessment of the pigments and actual state of conservation. Here, we employed technical photography in the visible and near infrared regions, using panoramic stitching techniques in order to obtain high resolution images of the very large artworks. Several conservation problems were observed such as: detachment of pigments, cracks, stains, and sections with undocumented restorations. In the IR and False Colour Infrared images we observed a very conspicuous behaviour of the red pigment used in the three paintings. Particular areas with the red pigment were fluorescent, and by means of ultraviolet fluorescence imaging we identified the pigment as through its red-coral fluorescence as Madder Lake, by comparison to a historical pigments reference palette. Measurements in five different red pigmented zones using UV–Vis spectroscopy in The Music show bands in the (550–650) nm region. A Lorentz Model nonlinear curve fit to the bands allowed us to correlate the fluorescent pigment in the paintings of Vespasiano Bignami with Madder Lake.