The Science Behind Detecting Art Fakes

On March 15, 2019, famed auction house Sotheby's announced that it would be selling off one of the most iconic paintings in the world: one of Claude Monet's haystack or Meules paintings.

There are actually 25 haystack paintings that comprise the series, but only eight are in private hands, and only four have come to auction during this century. The rest of the series are in the collections of The Metropolitan Museum of Art in New York, the Musee d'Orsay in Paris, and the Art Institute of Chicago.

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Sotheby's puts the painting's estimated sales price at over $55 million, so before you start scrounging around in your couch cushions looking for spare change to buy it, how do you know if you're buying the real thing and not a fake? The answer is: you hire a forensic art detective.

The Forensic Art Detective's Arsenal

The first thing a forensic art detective will do is look at the painting through a microscope. This is called microscopy, and art detectives use a stereo microscope, which allows them to see the various layers of paint in 3D. This can tell them if the paint was applied after the picture was originally painted.

Microscopy also examines the craquelure of a painting. These are the cracks that appear within the paint of old paintings over time, and they can be as individual as a fingerprint. 

Craquelure patterns differ from one country to the next, and from one era to the next. If a painting doesn't have the correct craquelure pattern for the country and era in which it was painted, then it's probably a fake.

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The next weapon in an art detective's arsenal is mass spectrometry. A mass spectrometer measures the masses of the molecules within a sample of paint taken from an artwork. The results are displayed in a chart known as a spectrum.

 Art detectives can compare the spectrum of painting to other spectrums taken from the artist's known works, and if they don't match, then the painting is most likely a forgery.

Mass spectrometry is often used to detect the presence of lead. The pigments used in very old paintings contain lead, while those used in more modern works don't, due to the risk of lead poisoning.

If the mass spectrometer detects the presence of a pigment that wasn't manufactured until say, 1975, and a painting contains it, then the painting probably isn't by Leonardo da Vinci.

The next weapon used by art detectives is an x-ray. Art forgers know that the age of a canvas can be determined, so they acquire a lesser-known painting from the same era as the painting they want to copy, and they paint over it. 

X-ray allows an art detective to see if there is another painting underneath. Unfortunately, this method isn't foolproof because most artists were poor during their lifetimes, and they often reused their canvases and painted over them. If an art detective sees poker playing dogs beneath what is supposed to be a Rembrandt, it's probably a fake.

On TV and movies, artists are often portrayed as slapping paint onto a canvas freehand, but the reality is that most artists first make a detailed underdrawing that helps guide a painting's structure. Artists stick to the same materials, such as pencil, charcoal or paint, to make the underdrawing, and they stick to the same techniques. 

Infrared reflectography allows a forensic art detective to see a painting's underdrawing. Unlike visual light, infrared light penetrates all the layers of paint down to the canvas, then it is reflected back to a special camera. If an underdrawing differs from an artist's usual method, or is missing entirely, then the artwork is probably a fake.

Provenance is the art world's term for an artwork’s ownership history. While some paintings have perfect provenance, written in the spidery hands of 17th and 18th-century record keepers, other paintings have large gaps in their provenance.

During WWII, thousands of artworks were illegally seized by the Nazis, and their provenance was deliberately obscured. Art detectives dig through public and private records, archives, histories, correspondence, sales catalogs, and receipts while researching a painting's provenance, and sometimes, they uncover previously unknown records of an artwork’s existence.

Stolen Art

Sites, such as the Art Loss Register, and the National Stolen Art File run by the U.S. FBI have extensive databases of stolen art. Wikipedia has a page devoted to stolen paintings.

Among the most famous stolen paintings are three that were taken from the Isabella Stewart Gardner Museum in Boston, Massachusetts during the St. Patrick's Day celebrations on the night of March 17, 1990. They are:

Also outstanding are:

Shown here Rembrandt's "Landscape with Cottages" in a black and white image from a catalog, which was taken from the Montreal Museum of Fine Arts on Sept. 4, 1972, and

"View of Auvers-sur-Oise" by Paul Cezanne disappeared from the Ashmolean Museum, Oxford, England during a fireworks show for the Millennium celebrations on December 31, 1999.