UNCOVERING
THE PIGMENTS
AND TECHNIQUES
USED TO PAINT
THE BERLIN WALL
Street art takes many forms, and the vibrant murals
on the Berlin Wall—both before and after its fall—
capture expressions of public opinion. However, the
secrecy surrounding their creation often complicates
efforts to preserve them. Now, researchers reporting
in the Journal of the American Chemical Society have
analyzed paint chips from this historic site using a
combination of a handheld detector and artificial
intelligence (AI) data analysis to uncover valuable
information.
“This research highlights the powerful synergy
between chemistry and deep learning in quanti-
fying materials, as demonstrated by the pigments
that make street art so captivating,” said Francesco
Armetta, a co-author of the study.
Restoration and conservation efforts depend on
understanding the materials and techniques used
in artwork. However, Berlin Wall painters didn’t
document their processes. In past studies of other
historic artifacts, scientists used nondestructive
techniques like Raman spectroscopy to identify
pigments in fragments brought to the lab. While
portable Raman devices allow for on-site analysis,
they lack the precision of full-sized lab equipment. To
address this, 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.
Magnified images revealed that the chips
contained two or three layers of paint, with visible
brushstrokes. A white base coat, likely used to
prepare the wall, was present in the layer closest to
the masonry. Using a handheld Raman spectrom-
eter, the researchers compared the paint chips’
spectra to a commercial pigment library. They
identified the primary pigments in the samples as
azopigments (yellow and red chips), phthalocyanins
(blue and green chips), lead chromate (green chips),
and titanium white (white chips). These results were
confirmed with additional nondestructive tech-
niques, 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 titanium white in varying ratios,
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, the researchers explained. They trained
a machine-learning algorithm with the Raman spec-
tral data from these mixtures to determine pigment
percentages. The approach indicated that the Berlin
Wall paint chips contained up to 75% pigment,
depending on the color tone, and varying levels of
titanium white.
The researchers suggested their AI-enhanced
approach could provide high-quality information for
art conservation, forensics, and materials science,
especially in situations where transporting lab equip-
ment to a site is impractical.
The study was supported by the Project Eurostart
“Punic or Greek weapons? The answer in the invis-
ible” and EEPP Italian Ministry of Universities and
Research Funds.
The paper’s abstract and supporting information
are available at http://pubs.acs.org/doi/abs/10.1021/
jacs.4c12611.
SCANNER
Micrographs of the surface and
cross-sections of representative
fragments from the Berlin Wall,
which was the subject of a recent
study aiming to develop an AI
algorithm to more accurately
analyze data and identify the
pigment and dyes originally
used to paint the wall.
8
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CREDIT:
JOURNAL
OF
THE
AMERICAN
CHEMICAL
SOCIETY

THE ASNT
FOUNDATION
ANNOUNCES US
DEPARTMENT OF
LABOR APPROVAL OF
NDT APPRENTICESHIP
GUIDELINES
In December, the ASNT Foundation
announced the approval of the new
national guideline standards for a
Nondestructive Testing Technician
apprenticeship. These guideline stan-
dards have been developed in collabo-
ration with industry experts and the US
Department of Labor to ensure compre-
hensive training and rich on-the-job
training opportunities for aspiring
Level II NDT learners. These guidelines
provide a framework for developing and
implementing effective apprenticeship
programs that meet the evolving needs
of the NDT industry.
The newly approved standards are
designed to ensure apprentices acquire
critical skills, knowledge, and behav-
iors through structured training and
on-the-job learning. With this approval,
the guidelines align with national quality
and regulatory standards, making them
an essential tool for fostering workforce
development and securing federal
funding and industry support.
“This approval marks one more
step the ASNT Foundation is taking to
support the NDT workforce,” said ASNT
Foundation Executive Director Heather
Cowles. “By developing resources and
models like this, we can assist our part-
ners with their training and development
needs. This brings us closer to building
a robust pipeline of NDT professionals
prepared to meet the workforce of the
future.”
The ASNT Foundation, the philan-
thropic arm of ASNT, is committed
to educating employers, educators,
and job seekers about the benefits of
apprenticeships. These efforts kicked
off during National Apprenticeship
Week, 17–23 November 2024, with a
series of webinars. These webinars
highlight how the approved guidelines
can streamline training programs, foster
collaboration among stakeholders, and
address workforce gaps identified in
the Foundation’s recent industry readi-
ness report.
“We are excited to provide tools
that enable schools and employers to
build strong partnerships to implement
structured, impactful apprenticeship
programs,” said Beonica Rutherford,
Workforce Development Manager at
the Foundation. “Apprenticeships will
allow NDT students and job seekers the
opportunity to earn and learn, reducing
barriers to enter into the industry.”
For more information on the webi-
nars, visit foundation.asnt.org or contact
Beonica Rutherford at brutherford@asnt.
org.
INFRASTRUCTURE
INSPECTIONS WITH
DRONES MADE EASIER
UNDER NEW UK RULES
The UK Civil Aviation Authority (CAA)
announced last October that it will now
allow drones to fly beyond the visual
line of sight (BVLOS) of remote pilots in
so-called ”atypical” operations through its
new policy for atypical air environments
(AAEs), marking a significant milestone
for the future of drone operations.
The policy aligns with the CAA’s
roadmap for safely integrating BVLOS
operations into UK airspace while
protecting people and property on
the ground. AAEs are defined as areas
where the likelihood of conventional
aircraft operations is minimal due to
proximity to infrastructure or buildings.
DATAFACTS |
INSPECTION CAMERA SYSTEM MARKET
The global market for inspection camera systems is driven by the growing demand
for preventive maintenance and safety across sectors like construction, automotive,
and utilities. Technological advancements, such as high-performance CMOS sensors
for low-light industrial environments, and durability improvements in hardware are
also contributing to market expansion. According to S&S Insider, the inspection camera
system market size was valued at US$351.98 million in 2023 and is expected to reach
US$933.51 million by 2032.
Source: S&S Insider, December 2024 snsinsider.com/reports/inspection-camera-system-market-5001
900
800
700
600
500
400
300
200
100
0 2023 2032
US$351.98 million
US$933.51 million
INDUSTRYNEWS
|
SCANNER
Market forecast to grow at a CAGR of 11.47%
F E B R U A R Y 2 0 2 5 • M A T E R I A L S E V A L U A T I O N 9
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USD
in
millions