Unveiling the Secret Chemistry of Street Art by a Multitechnique Approach

In recent years, graffiti and street art have gained recognition as legitimate art forms, deserving of the same care and attention as traditional art. As a result, conservators and restorers are now working to develop standardized guidelines for the cleaning, conservation, and restoration of these vibrant works. Our study takes a closer look at the materials used in street art, specifically the spray varnishes used by artists. Samples from two murals created in 2021 in Bari, Italy, are analyzed using a range of advanced techniques such as attenuated total reflection Fourier-transform infrared spectroscopy, reversed-phase liquid chromatography coupled with UV-Vis and electrospray ionization mass spectrometry (MS), and laser desorption ionization MS as well as pyrolysis-gas chromatography/MS. Acrylic, polyvinyl acetate, and styrene-acrylic resins are identified as the primary binders used in street art spray varnishes, along with common additives such as polyethylene and polypropylene glycol. The organic dyes and pigments, such as yellow (PY74), orange (PO36), red (rhodamine), and blue (phthalocyanine) hues used to create colorful images of street art, are also characterized. This study demonstrates the importance of a multitechnique approach in understanding the complex chemistry of modern spray varnishes used in street art.