Field and Laboratory Spectroscopic Methods for the Identification of Pigments in a Northern Italian Eleventh Century Fresco Cycle

The pigments of an XI-century fresco cycle in a small pre-alpine church of northern Italy were characterized by means of field techniques, in particular imaging spectroscopy, and laboratory spectroscopic techniques, namely total reflection X-ray fluorescence, micro-Raman, micro-Fourier transform-Raman, and micro-Fourier-transform infrared spectroscopies, thus achieving a complete identification of the ancient painter's palette. Advantages and limitations of each technique in its application to the study of fresco pigments are discussed. The artistic value of the fresco cycle and the religious role in the year 1000 of the church where it is located (S. Michele Arcangelo in Gornate Superiore, Varese, Italy) were demonstrated by the precious and elaborate materials used by the painter. Different pigments were used for different hues of the same color, e.g., azurite, carbon, and the most precious lapis-lazuli for blue, while mixtures of pigments were recognized in details having a particular tint, e.g., lapis-lazuli and minium for violet.