Multi-Analytical and Non-Invasive Approach for Characterising Blackened Areas of Originally Blue Paints

Azurite, a natural mineral pigment consisting of basic copper carbonate (2CuCO<sub>3</sub>·Cu(OH)<sub>2</sub>), is one of the Middle Ages’ most common blue pigments. Why paintings originally coated with azurite appear blackened today remains debated. Using a non-invasive mult...

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Main Authors: Maria Labate, Maurizio Aceto, Giacomo Chiari, Simone Baiocco, Lorenza Operti, Angelo Agostino
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/29/24/6043
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author Maria Labate
Maurizio Aceto
Giacomo Chiari
Simone Baiocco
Lorenza Operti
Angelo Agostino
author_facet Maria Labate
Maurizio Aceto
Giacomo Chiari
Simone Baiocco
Lorenza Operti
Angelo Agostino
author_sort Maria Labate
collection DOAJ
description Azurite, a natural mineral pigment consisting of basic copper carbonate (2CuCO<sub>3</sub>·Cu(OH)<sub>2</sub>), is one of the Middle Ages’ most common blue pigments. Why paintings originally coated with azurite appear blackened today remains debated. Using a non-invasive multi-analytical approach, the study analysed several unexpectedly black-appearing details (objects such as books or clothing such as veils, robes, or mantles) in Antoine de Lonhy’s works. The aim was to investigate if the black colour was due to intentional iconographic reasons, incautious restoration work, or painting deterioration. The analytical results displayed the presence of the blue pigment azurite, therefore, the expected original colour of various areas should be blue. To shed light on the discussion regarding the blackening, several other Renaissance paintings with similar black details were analysed, all from the same period and geographic area as de Lonhy’s works and conserved under identical conditions. The reasons why the blackening takes place are still unclear. However, the combined use of X-ray fluorescence spectrometry (XRF), UV-visible diffuse reflectance spectrophotometry with optical fibres (FORS), portable X-ray diffraction (XRD), and the elemental mapping based on the XRF data revealed that these blackened areas were originally painted with azurite, suggesting they were once blue. This finding significantly changes the overall appreciation of these artworks.
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spelling doaj-art-12509f89c8d746ac97b7a0bd72fa68272025-08-20T02:01:08ZengMDPI AGMolecules1420-30492024-12-012924604310.3390/molecules29246043Multi-Analytical and Non-Invasive Approach for Characterising Blackened Areas of Originally Blue PaintsMaria Labate0Maurizio Aceto1Giacomo Chiari2Simone Baiocco3Lorenza Operti4Angelo Agostino5Dipartimento di Chimica, Università degli Studi di Torino, Via P.Giuria 7, 10125 Torino, ItalyDipartimento per lo Sviluppo Sostenibile e la Transizione Ecologica (DISSTE), Università degli Studi del Piemonte Orientale “Amedeo Avogadro”, Piazza S. Eusebio 5, 13100 Vercelli, ItalyGetty Conservation Institute (Retired), 1200 Getty Center Drive, Los Angeles, CA 90049, USAPalazzo Madama—Museo Civico d’Arte Antica, Piazza Castello, 10122 Torino, ItalyDipartimento di Chimica, Università degli Studi di Torino, Via P.Giuria 7, 10125 Torino, ItalyDipartimento di Chimica, Università degli Studi di Torino, Via P.Giuria 7, 10125 Torino, ItalyAzurite, a natural mineral pigment consisting of basic copper carbonate (2CuCO<sub>3</sub>·Cu(OH)<sub>2</sub>), is one of the Middle Ages’ most common blue pigments. Why paintings originally coated with azurite appear blackened today remains debated. Using a non-invasive multi-analytical approach, the study analysed several unexpectedly black-appearing details (objects such as books or clothing such as veils, robes, or mantles) in Antoine de Lonhy’s works. The aim was to investigate if the black colour was due to intentional iconographic reasons, incautious restoration work, or painting deterioration. The analytical results displayed the presence of the blue pigment azurite, therefore, the expected original colour of various areas should be blue. To shed light on the discussion regarding the blackening, several other Renaissance paintings with similar black details were analysed, all from the same period and geographic area as de Lonhy’s works and conserved under identical conditions. The reasons why the blackening takes place are still unclear. However, the combined use of X-ray fluorescence spectrometry (XRF), UV-visible diffuse reflectance spectrophotometry with optical fibres (FORS), portable X-ray diffraction (XRD), and the elemental mapping based on the XRF data revealed that these blackened areas were originally painted with azurite, suggesting they were once blue. This finding significantly changes the overall appreciation of these artworks.https://www.mdpi.com/1420-3049/29/24/6043azuriteblue paintingsnon-invasive analysisFORSXRFXRD
spellingShingle Maria Labate
Maurizio Aceto
Giacomo Chiari
Simone Baiocco
Lorenza Operti
Angelo Agostino
Multi-Analytical and Non-Invasive Approach for Characterising Blackened Areas of Originally Blue Paints
Molecules
azurite
blue paintings
non-invasive analysis
FORS
XRF
XRD
title Multi-Analytical and Non-Invasive Approach for Characterising Blackened Areas of Originally Blue Paints
title_full Multi-Analytical and Non-Invasive Approach for Characterising Blackened Areas of Originally Blue Paints
title_fullStr Multi-Analytical and Non-Invasive Approach for Characterising Blackened Areas of Originally Blue Paints
title_full_unstemmed Multi-Analytical and Non-Invasive Approach for Characterising Blackened Areas of Originally Blue Paints
title_short Multi-Analytical and Non-Invasive Approach for Characterising Blackened Areas of Originally Blue Paints
title_sort multi analytical and non invasive approach for characterising blackened areas of originally blue paints
topic azurite
blue paintings
non-invasive analysis
FORS
XRF
XRD
url https://www.mdpi.com/1420-3049/29/24/6043
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