The study focused on the analysis of four panel paintings attributed to Francisco João, utilising various analytical techniques to investigate the colours and materials used in these historical artworks. Optical microscopy was employed to examine paint cross-sections, revealing information about pigments, mixtures, and paint layering. Micro-Raman spectroscopy aided in distinguishing between different pigments, such as vermilion and lead-tin yellow. HPLC analysis provided insights into the dyestuffs present in the paintings.
SEM-EDX analysis was conducted to identify inorganic pigments and study particle morphology in the paint layers. Micro Fourier transform infrared spectroscopy (μ-FTIR) was utilised to gather molecular information, aiding in the identification of binding media classes and degradation products resulting from paint ageing. The study highlighted the presence of lead white, carbon black, and lead-tin oxide as key pigments, with pigment mixtures used to create various colours.
Notably, smalt particles in the paintings exhibited discoloration and leached potassium, indicating potential deterioration processes. The research shed light on the complex interactions between pigments, binders, and environmental conditions, contributing to the understanding of colour palettes and conservation protocols for such multi-layered painting systems.
Overall, the study provided valuable insights into the materials and techniques employed in these historical artworks, offering a glimpse into the artistic practices of the time. By combining multiple analytical methods, the researchers were able to unravel the composition and condition of the paintings, enhancing our knowledge of art conservation and preservation strategies for similar works in the future.
