Analysis of Oval Paintings Attributed to the Painter Leandro Joaquim Using XRF and MA-XRF

Three paintings attributed to the Brazilian artist Leandro Joaquim (1738–1798) were analyzed in situ using X-ray fluorescence (XRF) and macro X-ray fluorescence scanning (MA-XRF) techniques. The artworks belong to the collection of the Museu Histórico Nacional in Rio de Janeiro and depict landscapes of the city during the colonial period. Due to their compositional and aesthetic similarities, the paintings have been treated as a collection. The analyses revealed the presence of pigments such as lead white (2PbCO3 .Pb(OH)2, green earth (K(Al,Fe 3+), (Fe2+,Mg)O10 (OH)2), raw umber (Fe2O3 + MnO2), and vermilion (HgS) in all three paintings. It was also observed that all the artworks contain a lead-based ground layer. To further investigate the similarities among the paintings, the XRF data were submitted to Principal Component Analysis (PCA), which confirmed the similarity in their elemental composition. The results suggest that the paintings were created using compatible materials and techniques, reinforcing the hypothesis of a common authorship and production within the same historical and technical context.