The article presents a preliminary diagnostic survey conducted on deteriorated paint layers of controversial mural paintings at the Maritime Station of Rocha do Conde de Óbidos in Lisbon. The research, focusing on decay phenomena and painting materials used by Almada Negreiros, aimed to identify and map the main deterioration features and underlying decay mechanisms. Laboratory analyses, including XRF and optical microscopy, were employed to investigate the composition of the paint layers and the presence of various pigments.
The study revealed that the yellows, browns, blacks, and light greens were the colours most affected by deterioration, with flaking and powdering being prominent issues. The glossiness observed on deteriorated paint layers raised questions about past restoration interventions and adhesive applications.
Furthermore, the research identified the presence of salts, such as gypsum and calcium oxalates, as significant contributors to the deterioration of the paint layers. The study highlighted the severe flaking observed in specific areas of the murals, indicating different degrees of loss in the affected colours.
The research findings suggest that the painting materials, techniques used by the artist, presence of salts, and past intervention products may all play a role in the deterioration of the paint layers. Overall, this multidisciplinary approach provides valuable insights into the condition of the historic mural paintings, emphasising the importance of understanding decay mechanisms for effective preservation and potential restoration efforts.
