Art fraud costs hundreds of millions each year. Works from well-known artists can sell for millions of dollars, so there's plenty of motivation for people to create forgeries. With forgers become ever-more technologically advanced, it is becoming harder to tell a forgery from the real thing. Now, a method using radiocarbon dating tied to 20th-century nuclear tests may provide help.
It turns out that radioactive isotopes from the WWII and Cold War nuclear tests made their way into the materials of many paintings, and their presence can now be used as a metric to test the authenticity of the works. Researchers have refined radiocarbon dating techniques to analyze small paint chips from old paintings and determine their age.
What does the process of radiocarbon dating paintings look like?
The process of radiocarbon dating was developed all the way back in the 1940s, right at the beginning of the nuclear age. It essentially allows scientists to determine the age of materials at any given point in history based on the ratios of carbon isotopes they contain.
Isotopes are atoms of an element that have different masses. Three isotopes of Carbon-Carbon 12, 13, and 14 are all abundant in living things, and the mix of these isotopes is consistent. However, while carbon 12 and 13 are stable, carbon 14 is unstable. Once organic matter dies, its carbon 14 atoms begin to decay. As a result, scientists can determine the age of dead organic matter, up to tens of thousands of years old, by calculating the ratio of these carbon isotopes.
Researchers can look at the ratios of Carbon isotopes in a fossil or tissue to determine exactly how long ago the organic matter was alive.
Measuring these ratios works fine in theory, but a kink was thrown into the mix when nuclear tests started kicking off in the 1940s. Above-ground nuclear bomb tests created tons of additional Carbon-14 isotopes from atmospheric nitrogen. In about 20 years of testing, the levels of Carbon-14 in the atmosphere virtually doubled.
This means that any organic materials present in the world during this time period contained unusually high amounts of Carbon-14, something researchers would have to account for in radiocarbon dating methods.
Known as the bomb peak, this period of rapid Carbon-14 creation presented a rather unique carbon signature in materials, such as the wood and fibers that in the frame or canvas of a work of art, or the organic matter used to bind the pigments in paint.
How nuclear testing-created Carbon-14 can be used to detect art forgeries
Identifying art forgeries is a fine art in itself, and has historically required a specialist trained in art history, artistic techniques and science. However, researchers began to consider how to use Carbon-14 radiocarbon dating to detect fake works. In fact, this idea was originally proposed in 1972, but it wasn't until 2015 that it was successfully tested by Italian researchers.
The researchers first used radiocarbon dating techniques to date the binder used in paints and on materials used in canvases. However, forgers have several ways to easily get around these tests, such as painting on canvases dating from the period of the original painting and using pigments made from similarly-dated materials.
In a study published last year, the researchers detail new ways that radiocarbon dating is advancing in being able to distinguish forgeries.
The team was able to analyze strands of canvas that were just a few millimeters long, and a tiny spec of pain about a millimeter in area. These samples were taken from a painting that was a known forgery, but quite a good one.
The painting was supposedly from 1866, but the forgery was actually created in 1980 by Robert Trotter, an artist who was later jailed for his work in forging famous works.
Before testing the specimens, they were cleaned thoroughly using solvents and then heated to 1,750 degrees Fahrenheit, causing the samples to release carbon dioxide. The released gas was captured and placed in a particle accelerator, where the carbon atoms were sorted and analyzed.
Rober Trotter was well known for reusing old canvases in his forgeries, and the results from the canvas were inconclusive.
However, when the team analyzed the binder in the paint, they were able to find that the levels of Carbon-14 isotopes in the oil dated back only to 1958, long after the original work's creation.
Despite this success, it is important to remember that using radiocarbon dating to identify forgeries is just one tool in the inspector's arsenal. It still can't be used to test the validity of all suspected forgeries.
It's also a destructive process, requiring samples from the work that can harm the original. One of the benefits of this new study was that the researchers were able to perform the radiocarbon dating process on pieces of art that were so minuscule, they were unlikely to be missed.
And there is another problem with this technique in identifying forgeries; the peak in Carbon-14 that from nuclear tests seems to be slowly disappearing. The atmosphere is set to return to pre-bomb levels in a few years. This will ultimately mean that radiocarbon dating in the future could lead to more inconclusive results. This will complicate matters even further for researchers as they try to determine whether a piece of art is a forgery or not.
However, at the end of the day, thanks to the massive amounts of nuclear testing throughout the 40s, 50s, and 60s, researchers have another tool in our back pocket to detect forgeries in the art world. It will likely still be useful in the future but may require more technical know-how to develop as time goes on.