Tag Archives: street art

Street art, the Berlin Wall, and handheld Raman spectroscopy devices with some assistance from AI (artificial intelligence)

Leave a reply

A December 11, 2024 news item on ScienceDaily describes research into preserving street art such as that found on the Berlin Wall,

Street art takes many forms, and the vibrant murals on the Berlin Wall both before and after its fall are expressions of people’s opinions. But there was often secrecy around the processes for creating the paintings, which makes them hard to preserve. Now, researchers reporting in the Journal of the American Chemical Society have uncovered information about this historic site from paint chips by combining a handheld detector and artificial intelligence (AI) data analysis.

“The research highlights the powerful impact of the synergy between chemistry and deep learning in quantifying matter, exemplified in this case by pigments that make street art so captivating,” says Francesco Armetta, a co-author of the study.

…

For anyone unfamiliar with the Berlin Wall (Wikipedia entry), it divided east from west in the city of Berlin when East Germany was part of the Union of Soviet Socialist Republics (USSR),

This image of the Berlin Wall was taken in 1986 by Thierry Noir at Bethaniendamm in Berlin-Kreuzberg.CC BY-SA 3.0

A December 11, 2024 American Chemical Society (ACS) news release (also on EurekAlert), which originated the news item, expands on the topic,

To restore or conserve art, it’s important to collect information on the materials and application techniques. But the painters of the Berlin Wall didn’t document this. In previous studies of other historic artifacts, scientists brought fragments or even whole objects into the lab and, without destroying the samples, identified pigments on them using a technique known as Raman spectroscopy. Although handheld Raman devices are available for on-site investigations, they lack the precision of full-sized laboratory equipment. So, Armetta, Rosina Celeste Ponterio and colleagues wanted to develop an AI algorithm that could analyze the output of portable Raman devices to more accurately identify pigments and dyes. In an initial test of the new approach, they analyzed 15 paint chips from the Berlin Wall.

The researchers first magnified the chips and observed that they all had two or three layers of paint with visible brush strokes. The third layer in contact with the masonry appeared white, which they suggest is from a base coat used to prepare the wall for painting. Next, the researchers used a handheld Raman spectrometer to analyze the chips and compared them to spectra collected from a commercial pigment spectra library. They identified the primary pigments in the samples as: azopigments (yellow- and red-colored chips), phthalocyanins (blue and green chips), lead chromate (green chips) and titanium white (white chips). These results were confirmed with other non-destructive techniques, including X-ray fluorescence and optical fiber reflectance spectroscopy.

Then, the researchers mixed pigments from a commercial acrylic paint brand (used in Germany since the 1800s) with different ratios of titanium white, trying to match colors and the range of tints typical for painters. A knowledge of these ratios could help art conservators prepare the right materials for restoration, say the researchers. Using the mixtures’ handheld Raman spectral data, they trained a machine learning algorithm to determine the percentage of pigment. The approach indicated that the Berlin Wall paint chips contained titanium white and up to 75% of pigment, depending on the piece analyzed and according with the color tone. The researchers say these results indicate that their AI model could provide high-quality information for art conservation, forensics and materials science in settings where it’s hard to bring lab equipment to a site.

…

Caption: Close examination of these chips, labeled according to their blue, yellow or red color, that once belonged to art on the Berlin Wall reveals brushstrokes, multiple layers and the pigments used. Credit: Adapted from the Journal of the American Chemical Society 2024, DOI: 10.1021/jacs.4c12611

Here’s a link to and a citation for the paper,

Chemistry of Street Art: Neural Network for the Spectral Analysis of Berlin Wall Colors by Francesco Armetta, Monika Baublytė, Martina Lucia, Rosina Celeste Ponterio, Dario Giuffrida, Maria Luisa Saladino, Santino Orecchio. Journal of the American Chemical Society (J. Am. Chem. Soc.) 2024, 146, 51, 35321–35328 DOI: https://doi.org/10.1021/jacs.4c12611 Published December 11, 2024 Copyright © 2024 American Chemical Society

This paper is behind a paywall.

For anyone curious about Raman spectroscopy and visual art, I have a description of the technology (and its use for authenticating art) in my June 27, 2014 posting, “Art (Lawren Harris and the Group of Seven), science (Raman spectroscopic examinations), and other collisions at the 2014 Canadian Chemistry Conference (part 1 of 4),” scroll down about 40% of the way .

Removing vandals’ graffiti from street art with nanotechnology-enabled method and Happy Italian Research in the World Day and more …

Leave a reply

Happy Italian Research in the World Day! Each year since 2018 this has been celebrated on the day that Leonardo da Vinci was born over 500 years ago on April 15. It’s also the start of World Creativity and Innovation Week (WCIW), April 15 – 21, 2021 with over 80 countries (Italy, The Gambia, Mauritius, Belarus, Iceland, US, Syria, Vietnam, Indonesia, Denmark, etc.) celebrating. By the way, April 21, 2021 is the United Nations’ World Creativity and Innovation Day. Now, onto some of the latest research, coming from Italy, on art conservation.

There’s graffiti and there’s graffiti as Michele Baglioni points out in an April 13, 2021 American Chemical Society (ACS) press conference (Rescuing street art from vandals’ graffiti) held during the ACS Spring 2021 Meeting being held online April 5-30, 2021.

An April 13, 2021 news item on ScienceDaily announced the research,

From Los Angeles and the Lower East Side of New York City to Paris and Penang, street art by famous and not-so-famous artists adorns highways, roads and alleys. In addition to creating social statements, works of beauty and tourist attractions, street art sometimes attracts vandals who add their unwanted graffiti, which is hard to remove without destroying the underlying painting. Now, researchers report novel, environmentally friendly techniques that quickly and safely remove over-paintings on street art.

…

A new eco-friendly method can remove the graffiti that this person is about to spray on the street art behind them. Credit: FOTOKITA/Shutterstock.com

An April 13, 2021 ACS news release (also on EurekAlert), which originated the news item, provides details about this latest work and how it fits into the field of art conservation,

“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 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.”

Research fellow Michele Baglioni, Ph.D., (no relation to Piero Baglioni) and coworkers built on their colleagues’ work and designed a nanostructured fluid, based on nontoxic solvents and surfactants, loaded in highly retentive hydrogels that very slowly release cleaning agents to just the top layer — a few microns in depth. The undesired top layer is removed in seconds to minutes, with no damage or alteration to the original painting.

Street art and overlying graffiti usually contain one or more of three classes of paint binders — acrylic, vinyl or alkyd polymers. Because these paints are similar in composition, removing the top layer frequently damages the underlying layer. Until now, the only way to remove unwanted graffiti was by using chemical cleaners or mechanical action such as scraping or sand blasting. These traditional methods are hard to control and often damaged the original art.

“We have to know exactly what is going on at the surface of the paintings if we want to design cleaners,” explains Michele Baglioni, who is at the University of Florence (Italy). “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.”

Michele Baglioni and coworkers used Fourier transform infrared spectroscopy to characterize the binders, fillers and pigments in the three classes of paints. After screening for suitable low-toxicity, “green” solvents and biodegradable surfactants, he used small angle X-ray scattering analyses to study the behavior of four alkyl carbonate solvents and a biodegradable nonionic surfactant in water.

The final step was formulating the nanostructured cleaning combination. The system that worked well also included 2-butanol and a readily biodegradable alkyl glycoside hydrotrope as co-solvents/co-surfactants. Hydrotropes are water-soluble, surface-active compounds used at low levels that allow more concentrated formulations of surfactants to be developed. The system was then loaded into highly retentive hydrogels and tested for its ability to remove overpaintings on laboratory mockups using selected paints in all possible combinations.

After dozens of tests, which helped determine how long the gel should be applied and removed without damaging the underlying painting, he tested the gels on a real piece of street art in Florence, successfully removing graffiti without affecting the original work.

“This is the first systematic study on the selective and controlled removal of modern paints from paints with similar chemical composition,” Michele Baglioni says. The hydrogels can also be used for the removal of top coatings on modern art that were originally intended to preserve the paintings but have turned out to be damaging. The hydrogels will become available commercially from CSGI Solutions for Conservation of Cultural Heritage, a company founded by Piero Baglioni and others. CSGI, the Center for Colloid and Surface Science, is a university consortium mainly funded through programs of the European Union.

And, there was this after the end of the news release,

The researchers acknowledge support and funding from the European Union NANORESTART (Nanomaterials for the Restoration of Works of Art) Program [or NanoRestArt] and CSGI.

The NanoRestArt project has been mentioned here a number of times,

The project ended in November 2018 but the NanoRestArt website can still be accessed.