Restore real picture
It is important for researchers and restorers to know which colors were originally laid out by the author of the painting. However, the process complicates one nuance: under the influence of various conditions – temperature, humidity, and even changes in the vital activity of microorganisms – some colors can reverse over the years. At the same time, generating an original idea can be problematic. But today Joint Institute for Nuclear Research physicists can do this in several ways: non-destructive X-ray fluorescence analysis (XRF), electron microscopy, infrared and Raman spectroscopy methods, as well as neutron activation analysis, which acts as neutron activation analysis. the most accurate tool.
Employees at each facility begin their investigation using a portable XRF device. Applying this to the painting on the wall, they make a clear analysis of elemental composition. This allows you to determine on the spot which paint is used in most cases.
“With the aid of a portable spectrometer, we can name the elemental composition right on the spot. There are characteristic elements that determine the color of the pigment: for example, the presence of mercury in red paint indicates the use of cinnabar, whereas the presence of a large amount of iron indicates red ocher. The spectrometer has a certain depth of penetration – we see all the colored layers up to the plaster. But as a result, we learn only the general composition, as if the colors were mixed. We take a sample and analyze it in the lab to accurately layer the pigments.”Olga Filippova, Senior Investigator of the Neutron Activation Group of the JINR Neutron Physics Laboratory, explained to socialbites.ca.
With the help of stratigraphy (layer analysis method), it is possible to see how many and which layers are present in the sample. Polarized microscopy allows you to distinguish pigments based on their optical properties, and infrared spectroscopy helps determine the type of binder (what the dye is mixed with: egg white, animal fat, or other ingredients). Microchemical analyzes are also carried out in the laboratory.
Scientists use neutron activation analysis to more accurately study the frescoes – this is also done in the laboratory.
The sample is placed in a stream of neutrons, and as a result of nuclear reactions “transformations” occur, which we fix with the help of spectrometric equipment. Next, we process the recorded spectrum and calculate the exact elemental composition. Most of the elements we see are with precision from 1 atom to 1 million. For some, for example, gold, the ratio is more accurate – 1 to 1 billion. Based on the elemental composition, we can talk about the materials used: pigments and plasters,” explained Andrey Dmitriev, President of GNAA FLNP JINR.
However, you have to pay the price for accuracy over time: from taking a sample to receiving the first results, it takes one and a half to two months.
Scientists have already used all of the above methods in various cultural sites in Veliky Novgorod, Pskov and Moscow.
Black jacket turned red
In Veliky Novgorod, physicists used their instruments to study the 12th-century St. George’s Abbey of St.
Historically, the saint’s cloak was usually depicted in shades of red, but is currently black-brown with only a patchy bright red color appearing on it. The reason for this inconsistency was a real mystery to art historians.
Examination of the basic composition of the fresco found a significant lead content indicating the use of unstable white lead. They were the ones who “repainted” the fresco black.
“There are pigments that reverse color with various effects. They contain white lead – at first they have a white color, but then due to various factors – the vital activity of bacteria, changes in temperature and humidity – they decompose and turn black.
We found such a pigment in the image of St. George the Victorious – this explains the black color of the cloak, uncharacteristic for his image. Based on the data obtained, we performed a digital reconstruction and restored the color of the possible original author,” he said.
black White
Olga Filippova gave another example of the rebirth of color in the Smolensky Cathedral of the Novodevichy Convent in Moscow. According to him, the cathedral’s drum depicts the archangels in yellow, green and red robes. The first two coats are drawn in white, and in red clothing the coats are black. Such a difference in colors seemed strange to the researchers.
“When we examined the base composition, we found that there was a lot of lead in these black strips. For this reason, white lead or lead carbonate was used. This is not a very stable compound against external influences: temperature, humidity, some types of bacteria. Over time it turns into almost black lead oxide,” he explained.
There are examples of blackened monuments in Russia, Georgia, Europe. In this case, FLNP personnel showed that the black folds on the red garments contained altered white lead, while the white folds on the other colored garments were painted with solid whitewash.
“Based on the data obtained, we reconstructed the fresco fragment and as a result showed that the clothes of all colors were originally depicted in the same style,” added the scientist.
The true style of the Greek Theophanes
If you go to the Church of the Savior painted by the famous Greek Theophan on Ilyin Street in Veliky Novgorod, you can see that the paintings are black and red, almost monochrome.
Until now, art historians have not been able to come to a unanimous opinion about the reasons for the emergence of such an uncharacteristic palette.
“For art historians, this is a real mystery: is it the author’s reclusive palette or the result of environmental influences? To find the answer to this question, we began to examine another monument. In the Novgorod church of Simeon the God Receiver of the Zverin Monastery, only some parts of the images have uncharacteristic colors, for example, a red halo. We did a temperature experiment and compiled a scale of temperature transitions of the primary colors, and now we know which color changes at what temperature. Based on these data, we perform a digital reconstruction of individual fresco parts. We are currently preparing a publication on this subject,” he said.
Research on a fresco depicting the three apostles from the Church of Simeon has shown that under the influence of heat, the yellow ocher turns red within a few minutes. And indeed the date is that in 1471 III. It states that the church “burned” when Ivan conquered Veliky Novgorod. This may indicate a possible cause of the change in fresco color.
Kremlin riddles
Now scientists are working with art historians and restorers in the Assumption Cathedral of the Moscow Kremlin – they plan to reliably determine what the colors of the frescoes really are, carry out their digital reconstruction and understand how exactly this or that color has changed. In addition, the study will allow the verification of tender documents from the 17th century.
According to MNRCU restorer Alexandra Grebenshchikova, the complexity of this work lies in the fact that restorers of the 19th and early 20th centuries did not try to preserve the original appearance of the frescoes and proposed new murals in contemporary materials over old ones. Then there was the idea that the old painting was actually created in dark, somber colors. But in fact the painting of the 17th century was bright and radiant.
“The experts at the Assumption Cathedral had questions, and one of them was determining the age of the gilding. With our XRF tool, we can determine which century the illuminations belong to by comparing them with known examples from different centuries. “We will be able to set up the connector type in the lab,” said GNAA employee Natalia Glombotskaya.
As Olga Zakharova, senior researcher at the Moscow Kremlin Museums explains, art historians decided to check what materials could be found among what was known from the documents they were purchased. 1643, by decree of Tsar Mikhail Fedorovich Romanova.
Understanding the composition of the mixtures that make up the colored surface and their relationship to the purchased materials, verifying the documents is a scientific task.