Identification of colorants on XVIII century scientific hand-coloured print volumes

Two series of printed volumes, respectively, created in Parma and in Vienna at the end of XVIII century, were analysed in order to characterise the palettes used in the hand-coloured miniatures and to determine whether decoration had been carried out simultaneously to, or shortly after, the time of printing. The application of complementary non-invasive analytical techniques allowed to yield a thorough knowledge of the colorants present and to determine that artists used a mixing of ancient, traditional materials such as cinnabar, minium or indigo, and materials of recent introduction in late XVIII century such as gamboge, Prussian blue or blue verditer. There was no evidence of colorants created successively to the age of printing, so that it can be concluded that decoration could have been done at the time of printing. Interesting is the use of metal pigments in the Vienna volumes, either in powder form and in foil form as a basis to obtain iridescence effects, a clue to evaluate the great skillfulness of the artist. Among the colorants identified, particularly relevant is the identification of gamboge, a colorant almost exclusively used among Far Eastern Asian painters according to the literature; this fact suggests that information on the use of pictorial materials can be strongly updated by diagnostic analyses.