Historical watermark recognition is a highly practical, yet unsolved challenge for archivists and historians. This information enables more thorough contextualization of these prints in their use as teaching and research tools in the University collection. As a result, the prints and paper were attributed to a late eighteenth-century posthumous edition of Merian’s work while the colorants were dated to the early twentieth century. The work combined several different non-invasive analytical techniques: hyperspectral imaging (HSI), macro X-ray fluorescence (MA-XRF) mapping, surface normal mapping with photometric stereo, visible light photography, and visual comparative art historical analysis. Therefore, the prints underwent multi-modal, non-invasive technical analysis to assess the date and material composition of the prints’ coloring.

Such ambiguities posed challenges for the interpretation of these prints by art historians. Because early modern prints are often colored by early modern readers, or modern collectors, it was initially unclear whether the coloring on these prints should be attributed to the print maker, to subsequent owners or collectors, or to an art dealer. Northwestern University’s Charles Deering McCormick Library of Special Collections owns three hand-colored copperplate engravings that once belonged to an edition of Matamorphosis Insectorum Surinamensium by artist-naturalist Maria Sibylla Merian (1647–1717).

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