Multi-Modal, Non-Invasive Investigation of Modern Colorants on Three Early Modern Prints by Maria Sibylla Merian

Abstract

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). 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. Such ambiguities posed challenges for the interpretation of these prints by art historians. Therefore, the prints underwent multi-modal, non-invasive technical analysis to assess the date and material composition of the prints’ coloring. 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. 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. This information enables more thorough contextualization of these prints in their use as teaching and research tools in the University collection.

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“…27 Prussian blue has a very high tinting strength, and consequently, a low concentration of pigment is needed to achieve a dark and intense blue shade. 28 It is not surprising that the XRF signal for iron from passages painted with Prussian blue is generally low and is affected by the shielding effect of lead. The use of Prussian blue was confirmed by reflectance imaging spectroscopy in the SWIR.…”

Colour Analysis: An Introduction to the Power of Studying Pigments and Dyes in Archaeological and Historical Objects

“…However, in some cases, sampling is simply not an option, as the works of art under investigation are too precious or too fragile to allow for samples, even very tiny ones, to be removed from them. This is particularly true for artworks on parchment and paper, as highlighted in the contributions by Agostino et al [4] and Dill et al [5], respectively. The development of non-invasive and portable spectroscopic techniques is one of the most active research areas in heritage science.…”

“…This information was then used to underline the fact that certain pigments and colourants were used in a hierarchical way, thus providing further insight into the modus operandi of the artist. On the other hand, Dill et al's contribution showcases the potential of non-invasive imaging techniques as opposed to point analysis [5]. Macro-XRF (MA-XRF), hyperspectral imaging (HSI), photometric stereo imaging and transmitted light imaging were used to investigate three hand-coloured prints showing the work of artistnaturalist Maria Sibylla Merian (1647-1717) and answer questions related to the attribution and dating of the prints.…”

XRFast a new software package for processing of MA-XRF datasets using machine learning

“…Because the technique is well suited to the analysis of at 2D objects, it has been used extensively for the study of easel paintings, [5][6][7][8][9][10] but its application has been extended further to many other types artworks, such as illuminated manuscripts, [11][12][13] furniture, 14 antique statues, 15 stained glass, 16,17 wall paintings, [18][19][20] and works on paper. [21][22][23] The elemental images produced can then be used as a way of identifying areas for micro-destructive sampling but can equally be used to reveal hidden compositions 5,10,24,25 or pentimenti. 9,26 Importantly pigments are oen inferred from these maps based on the spatial co-occurrence of certain elements: emerald green, for instance, is frequently deduced from the combination of arsenic and copper; smalt is identied based on the presence of cobalt, nickel, arsenic, and potassium; vermilion is characterized by the simultaneous presence of mercury and sulfur; cobalt green is associated with the co-located presence of copper and zinc.…”