The article discusses the painting “The Descent from the Cross” by Pedro Nunes, created in 1620, which showcases orange-coloured fabrics with conservation challenges. Through detailed analysis using various techniques like scanning electron microscopy and X-ray spectroscopy, it was revealed that the orange colour is attributed to a complex artificial pigment made of amorphous arsenic sulphide.
This discovery is significant as it represents a rare documented case of extensive use of artificial arsenic sulphides in European easel painting, particularly outside Italy. The study highlights the unique composition of the pigment, consisting of spherical particles likely derived from orpiment through sublimation and condensation, combined with irregularly shaped particles resulting from solidification and fusion.
The research also delves into the conservation issues observed on the painting’s surface, linking them to the susceptibility of arsenic sulphides to photo-oxidation. The alteration of the pigment particles, especially near the painting surface, is indicative of this degradation process. The study sheds light on the historical context of artistic influences in Portugal during the Mannerist period, emphasising the diversity of materials accessible to artists and the regional variations in artistic practices.
Overall, the findings contribute significantly to the understanding of art materials used in European painting, enriching the knowledge of regional artistic traditions.
