CHEMICAL ASPECTS IN THE INVESTIGATION OF SOME TYPES OF EFFLORESCENCE IN CULTURAL ASSETS

The preservation of Cultural Heritage is undoubtedly important for the society, and Conservation Science must dedicate itself to attempts to minimize the inherent processes of degradation to which cultural assets are susceptible. In this context, the evaluation of the chemical aspects of the composition of the objects and their relation with the environment where they are located are essential for the understanding of the decay signs observed, supporting the establishment of effective conservation strategies. These characteristics are demonstrated here by vibrational spectroscopy, scanning electron microscopy and microbiological analysis of efflorescences observed in two types of paintings: a tempera on canvas painting ("Barco com bandeirinhas e pássaros", Alfredo Volpi, 1955) and an oil mural painting of the Throne Room of the National Palace of Mafra (18th-19th century, Mafra, Portugal). The challenges involved in the investigation of the efflorescences are demonstrated in both cases, suggesting the occurrence of degradation processes of different origins: in Alfredo Volpi's tempera on canvas painting, the migration of substances from the preparation layer to the surface of the pictorial layer and microbiological colonization; and in the mural painting the migration of calcium salts from the constituent materials of plaster and of neoformation, besides associated microbiological colonization.