Art Restoration and Raman Spectroscopy: How the historical watercolor Chinese White affects pigment photodegradation
Clara Bardeen
Jr./Sr. Division
Chemistry
Acknowledgements:
ACIF, Department of Chemistry, UCR
Dr. Kerry M Hanson, UCR
Mrs. M. Hampton, MLK High, COSMOS Instructor
Audio TranscriptAuto-generated
Hello. This presentation is on my project Art Restoration in
Roman spectroscopy.
How historical watercolor, Chinese white effects, Pigment degradation.
This project is very dear to me because art has
always been a comforting thing to me.
I actually started the Art Appreciation Club at my high
school. There are you can observe the changes in society
throughout history.
Changes in art trends or movements tend to be parallel
to drastic occurrences in history.
I'm subscribed to an art restorer on YouTube and his
videos air really well done.
I wanted to combine my interest in art and science.
So I asked myself how chemistry can help the art
community, where I eventually read about the recent use of
Raman spectroscopy and art conservation.
So why is are important.
Most people are familiar with Starry Night by van Gogh.
They relate to this pain in the feeling of serenity.
This painting creates art, helps us express and visualize our
emotions, and it also helps historians observed changes in history
from a scientific perspective.
Chemistry is also involved quite a bit.
For example, it's Byzantine manuscript was how white paint with
this whole fight turned black.
Another example.
It seemed here in the self portrait on the left
is that piece before restoration and the effects of Let's
Go Fight are clear.
Artists were discouraged by this rapid degradation and often used
the campus to show why, instead of actual paint in
18 34 there was a revolution in the art world
when Windsor and Newton created Chinese white, which replaced lead
sulfide zinc oxide.
It's very stable and mix well with other colors, which
allowed for an explosion of expression.
So where does Roman spectrums could be come in?
It provides a fingerprint of a molecule like the graph
on the left.
It can be used to tell a pigment is present
in an artwork.
But the most important aspect of Raman spectroscopy is that
it's nondestructive, which is crucial in art conservation.
Rahman works when a laser is used to excite a
molecule. The molecule vibrates and emits the photon that equals
the vibrations energy, the instrument to text, a shift in
frequency of the laser photon minus the vibration photon.
The result is a fingerprint that is dominant in the
segment. This is going to lead us to the experiment.
I saw the Chinese white uses zinc oxide, which is
clearly more stable than let's go fight.
But art with Chinese White still experiences degradation with cracking
and yellowing.
Zinc oxide is a known photo catalyst, which means that
it can create reactive oxygen species like the hydroxyl radical.
So I questioned if zinc oxide in Chinese white was
acting as a photo catalyst.
I hypothesized, I think oxide will increase photo degradation of
colored pigments because it can react with organic molecules in
these pigments.
The pigments tested for cadmium yellow hue, which has this
molecular structure on the left and methylene blue on the
right. I had 50 times more Chinese white than pigment,
based off of a literature reference in a career solution,
and, I think collected the Roman spectrum before and after
UV irradiation.
The samples were irradiated for an hour with solar simulated.
You ve one hour of this radiation is equal to
about a day for an art piece, which is clearly
not normal for like restoration.
Those would be, you know, hundreds of years.
So in future experiments, the samples could be radiated for
much longer to have clearer results.
Here are the first graphs I wanted to show them
so you could see that a full spectrum from 117
100 wave numbers was collected, and I also identified the
peaks. The methylene blue is consistent with literature values.
I could not find a documented Raman spectrum for canyon
yellow hue.
Specifically, it's interesting that cadmium yellow hue because of the
number of peaks.
It's clear that it does not just contain cadmium, but
it's an organic molecule.
Here we're taking a closer look into the 11 50
to 60 50 wave number range.
The top graph shows mentally and blue and water.
The dark blue is before a radiation, and the light
blue is after receiver.
Intensity decreasing after you ve which shows that the molecule
by itself and water degrades easily.
We also see a broadening around 1300 wave numbers, but
no real peak shifts.
This is that a new species may not be being
formed. The bottom graph shows nothing blue of Chinese white
and water.
We also see a general decreasing the intensity.
We also see a dramatic increase.
Around 14 33 wave numbers in the 1400 wave, number
peak shifted to 13 93 wave numbers.
We see something totally different with cadmium yellow hue by
itself, like in the top graph or of Chinese white
on the bottom graph.
There are no dramatic peak shift or a broadening detected.
However, The overall intensity dramatically increases while intensity changes are
expected. One of the size could be due to errors
such as the laser not being focused or the solution
not being completely dissolved.
A closer look at the molecular structures may offer some
insight. Methylene Blue doesn't have electron withdrawing groups.
The nitrogen methods substitutes are actually electron donating groups.
It is much easier for reactive oxygen species to steal
an electron from the nitrogen or even the sulfur and
molecule, because the molecule can't hold on to its electrons
easily. So what may be happening is that the zinc
oxide absorbs UV generate something like a hydroxyl radical, which
then reacts with the methylene blue, informs new bonds between
the sulfur and the oxygen or a carbonnel group.
This would make for new peaks around 14 43 or
13 93 wave numbers, which is consistent with these types
of bonds.
In the Literature Canyon yellow, it's a different molecule.
Nitro and carbonnel groups are electron withdrawing and help the
molecule hold tightly onto its electrons.
This would make it harder for any reactive oxygen species
to see an electron from the nitrogen lone pairs.
This explains by cadmium yellow, has a more stable spectrum,
the methylene blue.
I think that the reason that the intensity increases for
cadmium yellow of Chinese white could be because there were
differences in the focus point on the sample, which would
affect the collection efficiency.
Or it could be that more cadmium yellow dissolved into
the solution as it was irradiated.
This will lead us to the conclusion and a discussion
of her.
I think this project could go Firstly.
My hypothesis was proven incorrect for Communion Oh, Newton's website,
and it turns out that this point is given a
rating by the company, meaning it is incredibly stable.
So my data is consistent with the claims by Windsor
and Newton in the literature.
I couldn't find a Roman spectrum for this particular yellow,
and I'd like to look to see if maybe my
spectrum could be added to some of these databases.
Methylene blue.
My hypothesis has proven correct.
I almost methylene blue because in the literature has been
shown to degrade under titanium dioxide.
So I figured that the zinc oxide in Chinese white
was degraded as well, which turned out to be true.
This project really opened my eyes to how Roman spectroscopy
is used in the art world.
Because Roman shows a fingerprint for a pigment and because
I saw new peaks with methylene blue, I wonder if
you could work backwards, then restoring a degraded artwork.
There is a risk of actually worsening its condition.
Their stories may not be aware of the chemical composition
of the original pigment and select the wrong paint, which
could degrade to a different color.
But if Roman could provide a signature of the degraded
paint, the restore could select the right pigment and effectively
concerned. The peace where you would take the spectra of
degraded pigments in the database could be created.
So when an art restorer was looking to see what
pigment was originally there, they'd have that option.
This also works for forgery.
A restorer could take the spectra of different degraded paints
on a canvas.
A modern paint would degrade differently than an old paint,
and Roman could distinguish the separate paint This distinguished in
between, the separate paints could prove that a painting was
faked or foraged.
Finally, I'd like to point out that my project within
solution but in the real world, these pigments are on
different substrates during the experiment and solution can help us
figure out mechanisms or degraded products.
But future experiments could focus on different substrates, humidity, humidity
and substrate itself, as environmental factors like air pollution could
lead to very different results.
Thes samples were irradiated for an hour, but our could