Category: Science and Art

The NMR-MOUSE in Cultural Heritage

The NMR-MOUSE in Cultural Heritage

A MOUSE??! No, this is not a real living mouse that runs freely around cultural heritage sites if that’s what you have in mind. Nor is it a computer mouse to facilitate interaction between humans and computers. So what is it then?

The NMR-MOUSE stands for Nuclear Magnetic Resonance – MObile Universal Surface Explorer. I know this sounds like a tongue twister, but the simple way to view it is as a mobile NMR magnet. If you want to know what this means keep on reading. The NMR-MOUSE was initially developed in the group of Prof. Bernhard Bluemich at RWTH-Aachen University, currently being manufactured by Magritek, and it has many applications, including its use in the field of cultural heritage.

The science of the NMR-MOUSE

The NMR-MOUSE recording an experiment on a Beltracchi forgery.

The NMR-MOUSE is a mobile NMR sensor that records NMR experiments in low magnetic fields. These magnetic fields are few times smaller than the magnetic fields of the MRI magnets used in hospitals. Unlike the MRI magnets, which use superconducting magnets, the NMR-MOUSE uses permanent magnets (the black box in the picture) to create the magnetic field. A surface coil is then attached to the magnet. This coil sends radio-frequency pulses into an area of the sample which we want to investigate. The nuclei of the sample respond differently to these radio-frequency pulses depending on their environment. For example, if you’re comparing the response of a porous sample, such as a building wall, situated in a humid environment and one from a dry environment you will get very different NMR results. That is because the wall in the humid environment absorbs water and this leads to changes in the NMR signal. These signals are detected by the same coil that sent the radio-frequency pulses to the sample and we analyze them to extract different information about the sample.

The MOUSE is placed on a sliding table to move the sensor up and down, or left and right, with respect to the sample. This allows us to record NMR experiments at different depths in the sample and obtain a stratigraphy of the sample we measure. For example, we can see the different layers of a painting, monitor the water penetration into a wall painting and distinguish between the different anatomical structures of the bone.

Advantages of using the NMR-MOUSE in cultural heritage

There are two major advantages of using the NMR-MOUSE in cultural heritage:

  • They are portable instruments. This means that the experiments can be recorded on site at the location of the analyzed object. Therefore, we can do NMR experiments inside museums, in archaeological sites, or in any other location, such as morgues or police stations. You’re probably wondering what do the last two locations have to do with cultural heritage. In my research I’ve done experiments in both: in the morgue measuring a mummified human cadaver for a project on ancient mummies and bones, and in the police station measuring painting forgeries to develop a method that uses the NMR-MOUSE to authenticate paintings.
  • They are non-invasive tools. This is very important when working in cultural heritage because we want to make sure we don’t damage the sample during the experiments. When you work in cultural heritage you want to protect the objects from any possible damage.

Applications of the NMR-MOUSE in cultural heritage

Being a mobile instrument that can record NMR experiments non-destructively makes the NMR-MOUSE an excellent tool for analyzing precious objects of cultural heritage. Here are some examples of objects and the type of information we can obtain using the NMR-MOUSE:

  • Paintings – information on the types of paints and treatments used in paintings, stratigraphy and authenticity of paintings
  • Historical buildings and frescoes – monitoring moisture content in wall paintings and analyzing their stratigraphy
  • Ancient mummies and bones – information on the state of conservation of mummies and bones
  • Historical paper – characterizing the degradation of historical paper
  • Musical instruments – information about the wood structure and treatments of master violins

If you want to learn more about these different applications of the NMR-MOUSE to cultural heritage sign up for my newsletter in the box below and I’ll keep you updated on the new stories.

Watch out con artists: Science can end your art forger career

Watch out con artists: Science can end your art forger career

The most expensive Heinrich Campendonk painting was sold in 2006 for a price of $3.7 millions. The surprising element here is not the record price of this painting, but the fact that the most expensive Campendonk is not really a Campendonk. Its author is Wolfgang Beltracchi, and he could have kept on earning millions and millions of dollars from forgeries if Science hadn’t ended his career as a con artist.

Who is Wolfgang Beltracchi?

Wolfgang Beltracchi forgery of Max Ernst painting
Wolfgang Beltracchi forgery of a Max Ernst painting

Wolfgang Beltracchi is a con man, an art forger, and at the same time, a very talented artist. He forged paintings from many artists, including Heinrich Campendonk, Max Ernst, Fernand Léger, André Derain, and many others. Many museums, auction houses and art collectors form all over the world bought and displayed his paintings not knowing that they were, in fact, forgeries. Christie’s even had his art work on the front cover of their catalogue.

How did he do it?

To start with, we have to think of the tremendous amount of work he put into forging these paintings. He studied the style, tools and technique of painting of each artist he forged. After researching the artist’s work, he would imagine and create new paintings that that artist might have painted. Thus, he created the missing pieces from that artist’s collection by using the artist’s style and methods. Then, his wife, Helene Beltracchi, would talk to art dealers and sell the paintings by claiming that they’re from an art collection the Beltracchis inherited.

With all his talent and the hard work he put into creating these forgeries it’s no wonder he managed to deceive so many specialists. Even Max Ernst’ widow stated that Beltracchi’s forest was the best Max Ernst forest painting she had seen.

How did science end the career of this famous art forger?

Wolfgang Beltracchi was very successful in his career as an art forger. He earned lots of money and he and his wife were living big, owning a villa in Freiburg and a yacht, and enjoying expensive parties and trips. All this ended when they sold the “Red Picture with Horses” painting claiming it was a 1914 Campendonk, and the Malta-based company that bought the painting asked for a certificate of authenticity.

The scientists who authenticated the painting used a technique called Raman spectroscopy to investigate the chemical composition of the pigments. In Raman spectroscopy, we detect the scattered light from a sample after being hit by a monochromatic laser beam. The detected signal contains information about different molecular vibrational modes and can reveal whether there are multiple chemical bonds or heavy atoms involved and what kind of chemical groups are present in the sample. Each of them would appear as peaks in a certain region of the Raman spectrum. The presence of these features in a Raman spectrum acts like fingerprinting, and its analysis can eventually provide information on the chemical composition of a sample.

When the scientists applied this technique to small samples taken from “Red Picture with Horses” they found something that shouldn’t have been there. The analysis revealed the presence of titanium white, a pigment that was available to artists only after 1921. Thus, by identifying the chemical composition of the pigments, scientists revealed the forgeries of Beltracchi. To his credit, Beltracchi did do his homework and checked the chemical composition of the pigments before using them. Unfortunately (of fortunately) the manufacturer of the pigment didn’t mention the presence of titanium white on the tube of pigment he used. This marked the end of the Beltracchis’ criminal adventures, the police started uncovering their entire operation, both of them ending up in prison.

In my research, we are analyzing Beltracchi’s forgeries by mobile NMR (Nuclear Magnetic Resonance) and comparing the data on the forgeries with the data we record on the original paintings. The purpose of this research is to develop a method that uses mobile NMR in a non-invasive way to identify forgeries.

From art forger to artist

Wolfgang Beltracchi is both a really good artist and a very charismatic person. These are both very good qualities, but certainly not when you use them to deceive people. After spending some time in prison and paying for his previous actions, he is now trying to make an honest living by painting under his own name. If you like his story and you’re interested in his art, here’s where you can find out more about it: https://www.beltracchi-art.com/

You might actually still see some of his paintings in museums because he claims he still has many paintings on display in museums under the name of different artists. So next time you’re in the modern art section of the museum think about this: is this really a Max Ernst or a Campendonk that I’m admiring, or is it one of the Beltracchi forgeries? 

My three main take-away messages from Beltracchis’ story are:

  1.  We should appreciate art for the art itself and not for the name behind it.
  2.  Science is very helpful in analyzing art works and catching criminals.
  3.  If you want a successful career as an art forger, don’t use the wrong pigments!

Here’s a final thought for all art forgers out there: don’t underestimate science!

Heritage and Science – what do they have in common?

Heritage and Science – what do they have in common?

Scientific investigation of a painting by mobile NMR
Scientific investigation of a painting

Whenever I go to a new place, one of my favorite things to do is visiting museums. I love museums and I can spend days in museums (but also in bookstores) without ever getting bored. That’s because I love learning about past and present cultures. I love imagining how people people used to live in the past and what their lives were like based on the information we gather from the little we have left from them. For the same reasons I also love archaeological sites, visiting old castles and ruins.

How can Science help the field of cultural heritage?

Most of the information we have about all these objects is gathered by using Science in one way or another. Here are four ways we can use Science in studying historical and art objects:

Dating

In order to find out the age of a certain object we can use scientific dating methods that involve radioisotopes. Isotopes are variants of the same element, with the same number of protons in the nucleus, but different number of neutrons. Some of these isotopes are unstable, radioactive isotopes that, over time, decay into more stable elements. One of these radioisotopes that can be used for dating objects is carbon-14 (number 14 tells us that there are 8 neutrons and 6 protons in the nucleus of this isotope). This is called radiocarbon dating. This element decays in time, a very long time – about 5730 years – to the more stable element nitrogen-14. Because we know this value, called the half-life, we can use radiocarbon dating to determine the age of objects that contain this isotope. This can be used for dating paintings, parchments, bones and other objects that are made from organic matter.

Art conservation

Different environmental factors, such as humidity, temperature or certain chemical and biological factors can lead to the deterioration of cultural heritage objects and sites. Using science we can identify the best conservation conditions for different objects based on the chemical composition of the object. Knowing what the objects are made of, we can understand what kind of external factors are most likely to lead to their deterioration. Once we have this information we can construct the ideal environment for each type of object. Thus, if we’re trying to conserve an object most prone to bacterial attack we would keep the object in a chamber of inert gas to reduce the damaging effects of bacteria. If we know that humidity is the problem, which is often the case of wall paintings and mosaics, then we can try to ensure dry preservation conditions for those objects. By keeping these objects in their ideal environment we can ensure their future conservation.

Art restoration

When the objects are in a poor state of conservation we need to go a step further – sometimes we can try to restore the objects to their original state. In time dust and other particles can accumulate on the surface of art objects, smoke and chemical reactions can lead to the discoloration of paintings and accumulation of patina on art objects made from metals, stone or wood. The first step of the restoration involves the cleaning of the object – a chemical cleaning for paintings and laster cleaning for objects covered by patina. After cleaning a painting, an art restorer could try to repair the tears in paintings, and eventually retouch the paint layer to return it to its original color. Extra care must be taken in the restoration process to ensure that the chemicals used for the cleaning and retouching are appropriate for that particular object. Any unwanted chemical reactions between the restoration materials and the art object can lead to bigger damages, and sometimes to the loss of art. This is why we need science in art restoration – to identify the correct materials we should use in restoring an art object.

Authentication of art

When it comes to authenticating art there are many scientific methods that we can use, all of them providing different information that could hint on whether an object is authentic or not. We can use dating methods, which will give us information about the age of the object. However, this method is invasive and not ideal when we’re dealing with a very precious object. Museums wouldn’t be too happy about scientists requesting samples of their most expensive paintings to analyze on a regular basis. Luckily, in the more recent year the amount of sample needed for this method is minimal and that opened new possibilities in radioisotopic dating. Other scientific methods provide information about the chemical composition of the different materials and pigments that could also be used to authenticate art objects. In my own research, we’re working on developing a method that uses nuclear magnetic resonance to authenticate paintings. All these methods are valuable tools for authentication of art, but ideally one would use a combination of the above-mentioned methods to assess the authenticity of art objects.

In future posts I will discuss specific case studies where all these scientific methods are applied in cultural heritage and I will explain in more details how each method works, why it works and when it doesn’t work.

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