Nanostructured fluids for the removal of graffiti – A survey on 17 commercial spray-can paints

Graffiti removal from monuments, such as statues or architecture, is becoming a priority for conservatorsand restorers. This operation is further complicated when the vandalism is carried out on surfaces thatshould be preserved, as in the case of writings or tags on historical wall paintings, or even on modernor contemporary pieces of street art. Several methods exist for graffiti removal, which include chemical,physical or biological approaches. However, traditional methodologies, such as the use of neat organicsolvents, are often unsuitable. Moreover, due to the great variability of brands and formulation of com-mercial paints, a thorough study of materials used for graffiti and a deep knowledge of their behaviorwhen exposed to cleaning media is currently lacking. In this contribution, we report a systematic labo-ratory survey on 17 different spray-can paints available on the market and commonly used for graffitiand vandalism in the Mexican area. These paints were analyzed by means of ATR FT–IR spectroscopy tocharacterize their composition. Several solvents, having different nature and polarity, were then used toremove the paints from glass slides. On the basis of these results, two different amphiphile-based nano-structured fluids, which present several advantages with respect to traditional cleaning methodologies,were formulated and tested on the same paint samples. Finally, the two nanostructured cleaning systemswere used for the removal of vandalistic graffiti from stones decorated with red pre-Hispanic paintingsin the archeological site of Ba’ Cuana, Asunciòn Ixtalpetec, Oaxaca, Mexico.