Calcium sulfate fillers and binders in Portuguese 15 th and 16 th centuries: Ground layers from a family painting workshop — Study by multianalytical spectroscopic techniques

Abstract

This study presents results on a developed methodology to characterize ground layers in Portuguese workshops. In this work a set of altarpieces of the 15 th and 16 th centuries, assigned to Coimbra painting workshop was studied, overall the masters Vicente Gil (doc. Coimbra 1498-1525), Manuel Vicente (doc. Coimbra 1521-1530) and Bernardo Manuel (act. c. 1559-94), father, son and grandson, encompassing from late gothic to mannerist periods. The aim of the study is to compare ground layers, fillers and binders of Coimbra workshop, and to correlate their characteristics to understand the technical evolution of this family of painters, using complementary microscopic techniques. The cross-sections from the groups of paintings were examined by optical microscopy and the results were integrated through the analysis obtained by μ-X-ray diffraction, scanning electron microscopy with energy dispersive X-ray Spectrometry, μ-confocal Raman and occasionally with μ-Fourier transform infrared spectroscopy imaging. Ground layers are of calcium sulfate, present as gesso grosso (mainly anhydrite with small amounts of gypsum) in the first and last phases of the workshop and gesso mate (mainly gypsum with small amounts of anhydrite) in an intermediate period. Binders have protein and oleic characteristics.

Novel nannofossils extraction methodology from paintings coupled with GC-MS for provenance determination and binder analysis

“…For those reasons, micro-sampling is important and often use for semi-destructive analysing techniques like cross-sections for light microscopy (LM) and scanning electron microscopy (SEM). There is a lot of artwork types and painting techniques that are evolving with time (8, [17][18][19]. This study focuses on historical paintings and polychrome statues with clay or chalks preparatory layers (8,20).…”

On the origin of Goa Cathedral former altarpiece: Material and technical assessment to the work of Garcia Fernandes, Portuguese painter from 16th century Lisbon workshop

“…The operating conditions for EDS analysis were 20 kV accelerating voltage and 10-12 mm working distance. Samples were analyzed in variable pressure mode at 40 Pa without carbon coating to be further analyzed by other analytical methods [30].…”

“…A microscope Hyperion 3000 controlled by software OPUS 7.2 from Bruker and a Mercury Cadmium Telluride detector are used in the spectrometer. For each spectrum a spectral resolution of 4 cm −1 in a working range of 4000-600 cm −1 and 64 scans were recorded [30].…”

Preparing the image: ground layers in Portuguese painting of 15th and 16th centuries – engraving and preparation

“…É o caso da oficina de Coimbra, onde podemos estabelecer comparações entre três gerações de pintores ao longo do século XVI [31]. Os desenhos subjacentes das pinturas atribuídas a Vicente Gil (doc.…”