A study of the blue colors used by Telemaco Signorini (1835–1901)

Telemaco Signorini (Florence 1835-1901), one of the most important Italian painters of the 19th century, was particularly famous among his colleagues for his way of depicting dark details and shadows by using primarily blue colors. The restoration of his painting Pascolo a Pietramala (c. 1889, Galleria di arte moderna, Palazzo Pitti, Florence) gave the authors the opportunity to study Signorini's blue palette using non-invasive fiber optics reflectance spectroscopy (FORS) in the ultraviolet (UV), visible (vis), and near infrared (NIR) regions (350-1700 nm). Furthermore, to help in the identification of the pigments used, a suitable spectroscopic database was created for Prussian blue, artificial ultramarine blue, Thénard blue (or cobalt blue), and cerulean blue modern blue pigments, in masstone and in mixtures with lead white as well as zinc white. The main pigments used by the artist in the aforesaid painting were found to be Prussian blue, artificial ultramarine blue, Thénard blue (or cobalt blue).