Pictorial materials database: 1200 combinations of pigments, dyes, binders and varnishes designed as a tool for heritage science and conservation

Abstract

The conservation of artworks requires a profound knowledge about pictorial materials, their chemical and physical properties and their interaction and/or degradation processes. For this reason, pictorial materials databases are widely used to study and investigate cultural heritage. At Centre for Conservation and Restoration La Venaria Reale (CCR) we prepared a set of about 1200 mock-ups with 173 different pigments and/or dyes, used across all the historical times or as products for conservation, 4 binders, 2 varnishes and 4 different materials for underdrawings. In collaboration with the Laboratorio Analisi Scientifiche (LAS) of Regione Autonoma Valle d'Aosta, the National Institute of Metrological Research (INRIM) and the Department of Architecture and Design (LAMSA) of the Polytechnic of Turin, we created a scientific database that is now available online (http://www.centrorestaurovenaria.it/en/areas/diagnostic/pictorialmaterials-database) designed as a tool for heritage science and conservation. Here we present a focus on materials for pictorial retouching where the hyperspectral imaging (HSI) application, conducted with a prototype of new technology, allowed to provide a list of pigments that could be more suitable for conservation treatments and pictorial retouching. Then we present the case study of the industrial painting Notte Barbara (1962) by Pinot Gallizio where the use of the database including modern and contemporary art materials showed to be very useful and where the fibre optics reflectance spectroscopy (FORS) technique was decisive for pigment identification purpose. Later in this research, the mock-ups' will be exploited to study degradation processes, e. g. the lightfastness, or the possible formation of interaction products, e.g. metal carboxylates.1 Mowilith DM5: PVAc and acrylic ester in aqueous solution, plasticizer free, Sinopia SAS datasheet [21]. 2 Linseed oil was also used as binder for gamboge, madder and indigo, as reported in literature.

Below the surface of the coffin lid of Neskhonsuennekhy in the Museo Egizio collection

“…FORS spectra acquired on some points of the red picture (Figure 3) allowed us to identify the red ochre and/or earth, as they showed an excellent correspondence with the spectral behaviour of the red ochre references collected in the CCR pictorial material database. [ 14 ]…”

“…[ 13 ] The pictorial material database recently realised at CCR was used for pigment identification. [ 14 ]…”

“Costruzione del viadotto”:MA‐XRFin the pictorial executive technique of Agostino Bosia

“…In this setting the apparatus works along a 350–1,000 nm wavelength range at around 0.5 nm step resolution. Identification by FORS is anyway easier when you can compare the artwork's spectral behaviour with the known pigments' one, [ 4–7 ] so that a good available database of known pigments and dyes is always required.…”

Camera Color Correction for Cultural Heritage Preservation Based on Clustered Data

“…Color studies of artworks could also make use of Infrared (IR) and Ultraviolet (UV) data (by means of, e.g., infrared reflectography, UV–Visible spectrophotometry, UV reflectance, etc.) or X-ray fluorescence spectroscopy (XRF) [ 3 , 4 ].…”

“…In the present study, 117 tiles from the database of diagnostic analyses of The Foundation Centre for Conservation and Restoration of Cultural Heritage “La Venaria Reale” (in collaboration with the National Institute of Metrological Research and Laboratorio Analisi Scientifiche of Regione Autonoma Valle d’Aosta) represent the basic dataset [ 3 , 20 ].…”