A multidisciplinary approach to the study of the brightening effects of white chalk ground layers in 15^th and 16^thcentury paintings

Abstract

This paper employs various techniques to analyze the mixture of chalk and binder materials used, by Portuguese and Flemish painters in the 15th and 16th centuries, to enhance the reflection of light in paintings.

Scrutinizing Ecce Homo: European or Indian painting? Assessment by Raman and complementary spectroscopic techniques

“…In lighter tones areas besides kaolinite (3,693 cm −1 ), μ‐FTIR technique has identified cerussite (1,051 and 678 cm −1 ), oil (2,931 and 2,858 cm −1 ), calcite (2,533, 1,412, 875, and 712 cm −1 ), gypsum (1,624 cm −1 ) were found (Sample 1, Table T1 [Supporting Information]). Refractive index of chalk/calcite (1.50–1.64) and gypsum (1.53–1.62) are inferior to lead white (1.94–2.09), resulting in an inferior covering capacity and reflective power . These pigment‐fillers were added probably to bring density to layer (happening also in other colours of the painting) and increase the transparency to the lighter tones, resulting in a more realistic loincloth representation.…”

A Painter in the Shadow: Unveiling Conservation, Materials and Techniques of the Unknown Luso-Flemish Master of Lourinhã

“…This sort of double ground layer is frequent in Lisbon painting workshops and particularly tending to the past examined work of Jorge Afonso's workshop [8]. The use of minium in the ground layer was probably a way to give the ground layers a less white and warmer tone to paint since gypsum has a significant refractive index when compared to chalk [9].…”

“…The painting's ground is made of calcium sulfate, is a gesso grosso ground layer (with more anhydrite than gypsum) ( Figure 11). Calcium carbonate, displayed within the upper region of the ground, was feasibly utilized as an extender, polisher and/ or finisher [6][7][8][9] and also as a ground layer, being a conceivable memory of the Flemish impact within the employment of chalk ground layers [9,18].…”

Novel nannofossils extraction methods from paintings, coupled with GC–MS for provenance determination and binder analysis

“…Several methods of provenance analysis can be used on painted artefacts. Trace elements, mineralogy, wood essence, palynology and organic matter analyses are some common ones [7,8]. Mineralogical analysis can be done with on-site non-invasive spectroscopic techniques like Fourier Transformed Infra-Red (FTIR) [9,10], Raman and X-ray fluorescence spectroscopy (XRF) [11,12] or UV Visible Reflectance (UV-VIS) [13,14], but only the surface and bulk analysis can be carried out this way.…”

“…There are several artwork types and painting techniques that have been evolving throughout history [8,[17][18][19]. The ground of a painting is made of one or more preparatory layers applied on canvas, wood panel or coarse wall, meant to flatten, smooth and homogenised before the pictorial layer.…”