Characterization of the Colorants in Antonio Raimondi's Botanical Watercolors by X-ray Fluorescence and Raman Spectroscopies

X-ray fluorescence (XRF) and Raman spectroscopic analysis of a set of 17 of Antonio Raimondi's botanical watercolors is performed. Results from this first non-destructive chemical study allowed one to understand the palette of this important Italian naturalist who registered Peruvian botanical history in the 19th century. Carbon-based black, vermillion, Prussian blue, chrome yellow, gamboge, lead white, yellow ochre, red lead, and hematite are the main colorants identified in these watercolors. In addition to this, azurite and lazurite are also detected by Raman but the absence of their corresponding signals in XRF analysis suggests that they may be mixed in small quantities with the main colorants. Finally, the presence of phthalocyanine blue and beta-oxy-naphthoic acid, modern synthetic colorants that are introduced in the 20th century, suggests a later intervention in a few of these illustrations. This information contributes to a better understanding of the materials used by Raimondi specifically, and of the colorants available to artists at that time in Peru.