Scientists unveil new way to save actual street art from graffiti

WASHINGTON — Walk along a busy city street long enough and the chances are high of running into some street art. Some famous, or in some cases infamous, artists (like Banksy) even contribute to these colorful scenes. Unfortunately, as street art has become more common, many vandals have taken it upon to themselves to make some unsavory additions of their own. Making matters worse, attempts at removing the graffiti usually end up destroying the underlying artwork as well. Luckily, researchers say there’s now a novel and eco-friendly way to quickly and safely remove graffiti from street art.

“For decades, we have focused on cleaning or restoring classical artworks that used paints designed to last centuries,” says Piero Baglioni, Ph.D., the project’s principal investigator, in a media release. “In contrast, modern art and street art, as well as the coatings and graffiti applied on top, use materials that were never intended to stand the test of time.”

The research team designed a “nanostructured” fluid based on non-toxic solvents and surfactants. This fluid is full of highly retentive hydrogels that slowly release cleaning agents to just the top layer of a surface. Therefore, it’s capable of removing an undesirable top layer (such as graffiti) within a matter of seconds to minutes. Even better, the process keeps the original artwork intact.

Difficult to separate the paint in street art and graffiti

Typically, both the street art and graffiti contain one or more of three distinct paint binder classes: acrylic, vinyl, or alkyd polymers. All three are fairly similar, which is what makes it so difficult to remove graffiti without harming the underlying paint. Before this new invention, the best way to remove graffiti was to use chemical cleaners or mechanical actions like scraping or sand blasting.

“We have to know exactly what is going on at the surface of the paintings if we want to design cleaners,” explains Michele Baglioni from the University of Florence. “In some respects, the chemistry is simple — we are using known surfactants, solvents and polymers. The challenge is combining them in the right way to get all the properties we need.”

After working through a complex process of characterizing each paint variety and then subsequently finding suitable low-toxicity, “green” solvents and biodegradable surfactants, the team put together their cleaning agent in the form of a hydrogel. From there, researchers carried out numerous tests to determine the ideal amount of time it takes for the solvent to safely remove graffiti.

Finally, the team successfully tested their hydrogel out on a tagged piece of street art in Florence, Italy. Not a speck of graffiti remains and the art is as beautiful as ever.

“This is the first systematic study on the selective and controlled removal of modern paints from paints with similar chemical composition,” Michele Baglioni concludes.

Researchers presented their findings at the spring meeting of the American Chemical Society.