Labate Maria, Aceto Maurizio, Chiari Giacomo, Baiocco Simone, Operti Lorenza, Agostino Angelo
Dipartimento di Chimica, Università degli Studi di Torino, Via P.Giuria 7, 10125 Torino, Italy.
Dipartimento per lo Sviluppo Sostenibile e la Transizione Ecologica (DISSTE), Università degli Studi del Piemonte Orientale "Amedeo Avogadro", Piazza S. Eusebio 5, 13100 Vercelli, Italy.
Molecules. 2024 Dec 22;29(24):6043. doi: 10.3390/molecules29246043.
Azurite, a natural mineral pigment consisting of basic copper carbonate (2CuCO·Cu(OH)), 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.
蓝铜矿是一种由碱式碳酸铜（2CuCO·Cu(OH)）组成的天然矿物颜料，是中世纪最常见的蓝色颜料之一。为何最初用蓝铜矿绘制的画作如今会变黑，这一问题仍存在争议。该研究采用非侵入性多分析方法，分析了安托万·德·隆伊作品中几个意外呈现黑色的细节（如书籍或衣物，如面纱、长袍或披风等物品）。目的是调查黑色是由于故意的图像学原因、不当的修复工作还是绘画变质所致。分析结果显示存在蓝色颜料蓝铜矿，因此，各个区域预期的原始颜色应为蓝色。为了阐明关于变黑现象的讨论，还分析了其他几幅具有类似黑色细节的文艺复兴时期绘画，这些绘画均与德·隆伊的作品处于同一时期和地理区域，并在相同条件下保存。变黑的原因仍不明确。然而，X射线荧光光谱法（XRF）、带光纤的紫外可见漫反射分光光度法（FORS）、便携式X射线衍射法（XRD）以及基于XRF数据的元素映射的联合使用表明，这些变黑区域最初是用蓝铜矿绘制的，这表明它们曾经是蓝色的。这一发现显著改变了对这些艺术品的整体评价。
