Street Art as Collective Memory—Materiality and Deterioration Factors

Street art has expanded across many cities around the world and is now an integral part of everyday life. These painted surfaces have been embraced by citizens as objects associated with neighborhood identity, expressions of political messages, and representations of iconic sport and music figures, among other forms of cultural expression. However, these artworks are prone to severe degradation due to exposure to outdoor environmental conditions, which negatively affects their preservation. Therefore, considerable efforts have been devoted to investigating the composition of street art paints and their degradation processes upon outdoor exposure. This review presents an updated overview of the main advances in the characterization of street art materials in commercial paints and outdoor mural paintings, focusing on the multi-analytical approaches that employ non-destructive and micro-destructive techniques. It also examines the effects of environmental conditions, particularly on the chromatic alteration of synthetic organic pigments, as well as recent advances in the development of protective coatings for outdoor mural paintings. Finally, this review aims to contribute to the advancement of research on street art materials and to promote the conservation of this cultural heritage.