Materials and methodologies for the conservation of outdoor contemporary mural paintings

Outdoor public art and painted murals, in particular, can improve the city's environment, bring communities together and deepen public understanding of community identity and culture1. Due to this important social role, murals are subjected to conservative actions through various and still under discussion methodologies since these artworks are not juridically defined as cultural heritage and, therefore, subjected to the current guidelines for traditional mural paintings. These interventions lead to different results regarding many variables: the painting techniques, the substrate layer typology, the environmental conditions, the materials used for the interventions, etc. This research aims to investigate the durability of conservative interventions, particularly for surface protection and consolidation, carried out with different materials and applied methods on murals located in urban, rural and mountain environments and prepared with various painting materials and techniques. Crossing these data allows us to individuate the best procedures for the different scenarios and, eventually, to modify the properties of already used materials to make them more suitable for specific situations. Non-invasive in situ surveys and analyses, such as optical microscope, Raman spectroscopy and multi-spectral analyses, are used 2 to evaluate the current state of conservation of the murals and a database has been built to collect all the information, including the climatic conditions after the interventions in each case study analyzed. Thanks to the collaboration of municipalities, foundations, and restorers involved in the maintenance and valorization of modern murals, it has been possible to collect a lot of information and access numerous case studies in very different environmental conditions3,4,5 and contribute to the suitable and durable preservation of this most important kind of art.