Chemistry Connections

Episode #12

Welcome to Chemistry Connections, my name is Jiya Pandit and my name is Olivia Kim and we are your hosts for episode #12 called the chemistry of art restoration and conservation. Today we will be discussing how many art pieces have been fixed and preserved through the application of chemistry concepts.

Segment 1: Introduction to Chemistry of maintaining and fixing art pieces

When you enter an art museum, you may forget the many efforts of artists, conservators, and even scientists behind the impressive masterpieces. Just as the paintings are something to marvel at, the meticulous process behind restoring and preserving the art works is just as fascinating. While the process of fixing art may appear to just consist of applying new layers, laboratory methods - some of which we have explored and learned about in AP Chemistry - are employed to ensure the best materials and techniques are being used to repair the artwork.

Although the techniques used to restore and conserve art can be very similar, there is a key difference between art restoration and conservation. Art restoration refers to the process of fixing an object so that it returns to its original condition or appearance, while art conservation refers to the process of preserving an artwork with the intent of preventing any further deterioration or discoloration. Art conservation was first introduced during World War 2 due to the findings of undamaged works from Michelangelo and Vermeer. This was one of the first leading causes for conservation practices after the war. A famous example of art restoration is of the Sistine Chapel frescoes throughout the 1980s-1990s. However, not all art restorations or art conservation efforts are successful, which is why chemistry and other scientific disciplines have had a greater presence in the field of art.

Segment 2: The Chemistry Behind Art Restoration and conservation.

Now that we’ve discussed the historical aspect of art restoration and conservation, let’s delve deeper into how it’s connected to chemistry. I will be covering art restoration, and later, Jiya will take over with art conservation!

Topic 1: Art restoration

The first part of fixing and maintaining art is the process of art restoration. Certain art restoration processes involve methods we’ve learned about this year, but it really depends on the material used to create the art (you’re going to hear me say this a lot!).

A crucial part of art restoration is making sure that the methods employed to fix the respective art piece are with the techniques and mediums used by the original artist. Especially in very old artworks, where the materials are not commonly used or easy to access today, applying scientific methods to art is necessary. To better understand the process, I will be talking about a specific art restoration case. In the restoration of “The Plague in Lucca'' (a painting done by Italian artist Lorenzo Viani), such methods were used. For some more context, Viani’s painting had undergone a restoration process post-WWII, however that was not very effective. Recently, the artwork has undergone another restoration, this time with a more scientific and successful approach.  

The restoration of Viani’s painting, as with many other artworks, was a two step process. The first part of the process - which relies heavily on non-invasive techniques - allows scientists and artists to look at the details of the painting, such as the different paint layers and the original colors of the artwork. Images of the painting were taken at different wavelengths, which relates to concepts of electromagnetic radiation we briefly covered this year in AP Chemistry. Since each element produces a different atomic spectrum and emits a unique light when electrons transition between energy levels, the multiband imaging method helped scientists determine what elements are found in the pigments of the painting. For example, in Viani’s artwork, samples of lead, zinc, mercury, chromium, barium, and iron were detected in the pigments. This technique also helps scientists identify the exact colors used by Viani, which is very helpful for art conservators. In combination with the emission spectrum, X-ray fluorescence (XRF) analysis is also used to determine what elements make up certain pigments in the painting. XRF can identify the chemical makeup of the pigments by measuring the fluorescent X-ray emitted by a sample when the samples becomes exposed to an X-ray source. Since each element produces a unique fluorescent X-ray (similar to multiband imaging), data from XRF can provide specific information about the pigments. For instance, data from XRF indicates that a mixture of vermillion (HgS - mercury (ii) sulfide) and chrome green (Cr2O3 - chromium (iii) oxide) pigments could have been used by Viani. 

The second part of the process involves destructive methods, including a combination of mass spectrometry, Raman analysis, and gas chromatography. Destructive methods give more insight about the exact nature of the chemical, since non-invasive techniques can only reveal so much. Very small samples of the artwork underwent the process of mass spectrometry and gas chromatography, and the results of these two methods provided valuable information about what oils were used to bind the pigments. Mass spectrometry is the process of injecting atoms from the sample into the mass spectrometer instrument, which produces a mass spectrum. The mass spectrometer uses deflection to determine an object’s mass, and this can be used to identify the specific elements in the sample. Knowing the chemical makeup of the oils that hold the pigments together is crucial to the art restoration process because art restorers want to fix the painting using mediums that are very similar if not identical to the materials used when the artwork was first created.

Even though I’ve focused on the chemistry of one specific art restoration case, the techniques used to restore Viani’s painting are fairly consistent with other cases. As I’ve said before, the laboratory techniques are very dependent on the age and materials of the artwork, but there is a general two step analytical process when deciding the best way to mend the painting.

Topic 2: Art conservation

The second part of preserving art is art conservation, which is the process of preserving art pieces whether it be architecture or even statues from future damages.  

A big part of conserving art requires a lot of in-depth research and analysis of either a painting or sculpture to receive accurate data regarding what procedure should be used to fix the art piece so that there isn’t much damage in the future. This is where the AP Chemistry topics, mass spectrometry and gas chromatography (known as GC/MS) come into play. These specific techniques allow biologists to identify the compounds within the art piece by taking a tiny piece of the art and placing it into a GC/MS machine, which can then help pinpoint what treatment should be used to conserve the art. The GC/MS machine can also determine the reasoning behind discoloration or cracks on a piece. 

For example, there was a mission for conserving Buddha statues of Bamiyan, which represent Buddhist Art. During the war in Afghanistan in 2001, the statues began to get popular and well known, causing the Taliban to destroy the statues. Through the following years, organizations began to conserve the destroyed statues using techniques such as GC/MS leading to the findings of the organic paint binders and a deeper understanding of cultures in Asia. Through AP Chemistry topics such as extractions, desalting, and hydrolysis, substances such as egg proteins in this specific conservation, from the samples can be determined via the GC/MS. 

So what’s the science behind this? The full procedure of the GC/MS occurs in multiple steps. The 1st step, like in art restoration, is analyzing the art. One way this can be done is through nano-indentation microscopy, allowing scientists to analyze small parts of a piece to figure out if there is degradation or oxidation by applying a force onto a small piece of the art. Once analyzing has finished, the 2nd step begins. Gas chromatography is the process of separating substances in a compound. Through the use of injecting the sample into a mobile phase, with the help of an inert gas, it picks up the substances to get tested. The other phase is the stationary phase, which is when the mobile phase passes through a column. The data gathered from the chromatography is transferred to a chromatogram, a graph that shows the different components in the sample, each represented by a peak. Adsorption, an AP Chemistry concept, also occurs during gas chromatography. Adsorption occurs during the stationary phase in the column causing the substance to separate. This leads to the mass spectrometry section where the spectrometry analyzes each gas, specifically the masses of each of the substances by deflection like Olivia said. Thus helping determine the actual substances in the art piece by comparing the masses to other known masses. 

Along with what I previously stated, although GC/MS can be very helpful in determining materials in the art piece, a particular aspect that scientists are still trying to figure out when trying to conserve art pieces, is whether or not the treatment going to be used is safe, that it won’t cause future damages, or that they wouldn't lose the original piece. However, removing surface dirt, varnish, retouching areas, and fixing dents, can have a big impact on small pieces that need conserving. 

Segment 3: Personal Connections

Olivia: You may be wondering why we chose this specific topic. The reason I chose the topic of art conservation and restoration is because I really enjoy making art in my free time, and I’m interested in potentially studying art history in college! Whatever I end up doing, I want to keep art a part of my life, so learning about how STEM related subjects - like chemistry - are directly related to artistic fields is really fascinating!  

Jiya: The reason that I chose art conservation and restoration as the topic is because I also have an interest in art, and although I'm not a great artist, it's entertaining and fun to do on the side! I don’t particularly want to do anything in the future related to art, but I know I want to keep art in my life whether it be drawing or painting and incorporating chemistry into art, two things that I enjoy, are really interesting to learn about and to see how chemistry is in even the smallest of things!

Thank you for listening to this episode of Chemistry Connections. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Sources:

• https://heritagesciencejournal.springeropen.com/articles/10.1186/s40494-015-0055-0 
• https://blogs.getty.edu/iris/conservation-tools-the-gc-ms-instrument/
• https://www.chemistryworld.com/features/the-art-of-conservation/3009092.article
• https://en.wikipedia.org/wiki/Mass_spectrometry 
• https://en.wikipedia.org/wiki/Gas_chromatography 
• https://www.brhoward.com/new-blog/2018/8/28/whats-the-difference-between-conservation-and-restoration 
• https://www.thermofisher.com/blog/ask-a-scientist/what-is-xrf-x-ray-fluorescence-and-how-does-it-work/ 
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5381772/ 
• https://asiarta.org/introduction-to-conservation/oil-paintings/painting-conservation-techniques/ 
• https://www.nature.com/articles/s41598-020-64892-7

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