Art forgers: What lies beneath

Forgers have been conning the art world for generations - but now a new detection system can spot even the best fakes, says Jimmy Lee Shreeve

According to European police estimates, as much as half the art in circulation on the international markets may be forged. And a fair number of fakes go under the hammer in London auction rooms too, which is why Scotland Yard now has a specialist art and antiques unit. Art forgery has become so common that hardly a year goes by without a big story breaking of how the art experts have been duped.

Last year it was the so-called "Bolton forgers", the father, mother and son team who hit the news after conning enormous sums out of the art world and museums selling fake sculptures, artefacts and paintings. The kitchen and garden shed of their council house in Greater Manchester doubled as one of the most prolific, and successful, art forgery studios in the world. When the arts and antiques squad raided the property in March 2006, they could hardly believe their eyes. "There were blocks of stone, a furnace for melting silver on top of the fridge, half-finished sculptures, piles of art books and a bust of Thomas Jefferson in the loft," recalls DC Ian Lawson from the unit.

It is thought that the family of forgers – George Greenhalgh, 84, his wife Olive, 83, and son Shaun, 47 – made about £2m from their scams, while claiming welfare benefits. They came unstuck when they tried to sell the British Museum an ancient Assyrian relief, having become overconfident after off-loading an Egyptian sculpture for nearly £500,000 in 2003. Errors in the cuneiform script – basically spelling mistakes – alerted the already suspicious museum staff, who immediately called Scotland Yard.

In 2006, Robert Thwaites, a 54-year-old artist with no formal training and failing eyesight, was sentenced to two years in prison for selling forged oil paintings by Victorian artist John Anster Fitzgerald, famous for his macabre fairy scenes. He operated for nearly five years – between 1999 and 2004 – before police nabbed him. Thwaites sold one of his fakes for £20,000 to Rupert Maas, a gallery owner and art specialist for the BBC's Antiques Roadshow. So convincing was Thwaites' work that Maas was able to sell it on for three times the price he paid for it. Gallery owner Christopher Beetles was also taken in, paying more than £100,000 for another of Thwaite's forgeries.

New technology, however, could put a stop to art forgers' scams. Earlier this year, scientists Joris Dik and Koen Janssens used a new technique to scan Vincent van Gogh's painting Patch of Grass, which was completed in Paris in 1887. After bombarding the picture with high intensity x-rays from a particle accelerator, they revealed a hidden portrait of a peasant woman. Because he was so poor, Van Gogh often reused his canvases (experts believe roughly a third of his works hide a second painting underneath).

Art historians have used x-rays for years to authenticate paintings and see what, if anything, lies underneath the main picture. But the results were in black and white and were usually fuzzy. The new method, however, provides far more detailed images of what lies beneath old masters, which could have major implications for the detection of fraudulent artworks. As one expert points out: "Now forgers will have to paint the underneath picture on the canvas before painting the forgery."

Dik, a materials scientist from Delft University in the Netherlands, and Janssens, a chemist from the University of Antwerp in Belgium, wrote about their technique in a recent edition of the journal Analytical Chemistry. They explained that the powerful x-ray bombardment caused atoms to emit "fluorescent" x-rays of their own, which highlighted the chemicals they originated from. This allowed the researchers to produce a colour map of the concealed picture.

"We visualised in great detail the nose, the eyes, according to the chemical compositions," says Dik. The scanning of the hidden portrait took two full days to complete. A long and protracted process, but a small price to pay if it can help thwart the art forgery scammers whose collective criminal enterprises are thought to be worth billions of pounds every year.

But the jewel in the crown when it comes to identifying the fakes from the real McCoy has been developed by scientist James Z Wang and his teams at Penn State and Princeton universities. The researchers used high-resolution, grey-scale scans of 101 paintings either by Van Gogh or done in his style. Eighty-two of these paintings had consistently been shown to have been by the Dutch painter, while six were long known to have been painted by others. Experts haven't yet been able to agree on the remaining 13.

The researchers took 23 out of the 82 authenticated works because they represented different periods of Van Gogh's life, during which his style changed. These were used to "train" the image analysis software in the nuances of Van Gogh's painting technique. Small areas of the paintings were then scanned and taken for individual analysis – the idea being to identify recurrent brush stroke patterns, texture and other features to create a mathematical model of the great artist's style. The remaining 78 pictures could then be set against the model and tested for authenticity.

The system proved promising. Two known Van Goghs, The Plough and the Harrow and Wheatfield with Crows, were run through the first level of the process. Using a standard measure of brush strokes, the software revealed that, out of the other paintings, a work depicting the sea at Saintes-Maries most resembled them. But this painting was a fake commissioned or sold by German art dealer Otto Wacker. However, when the image analysis system was intensified, the greater level of detail showed that the Wacker forgery was different to the genuine Van Goghs and must have been painted by someone else.

None of this could be seen with the naked eye. But according to Princeton University's Shannon M Hughes, a PhD student of electrical engineering working on the project, the computer revealed what she calls "wobbles".

"If someone was trying to copy someone else's work, you can imagine that he or she is probably painting more slowly, more tentatively," she explains. "As the painter speeds up and slows down during a brush stroke, he might deposit varying amounts of paint, whereas Van Gogh's own works revealed no such pauses."

In other words, Van Gogh's style was natural to him – he'd spent years developing it – whereas a copyist is going to give their trail away by being more hesitant because, no matter how proficient they are with a brush or pencil, the style is not natural to them.

Despite their undoubted success, Dr Wang and his team are still working to perfect their techniques. "Computerised image-processing systems should get better at detecting forgeries the more they can learn about artists' techniques and styles," he says.

Dr Wang and his team are also using other wavelengths, including ultraviolet, to analyse more of Van Gogh's brushwork. Once their system is perfected, the multi-billion pound art forgery industry could find itself feeling the pinch. Unless, of course, the forgers find ways to dupe the authentification technology, which is always a possibility...

Artistic licence: famous fakers

*Han van Meegeren (1889-1947)

Van Meegeren was a Dutch painter who focused on faking the works of Johannes Vermeer (1632-1675). Van Meegeren's most famous Vermeer fake, 'The Disciples at Emmaus', for example, was proclaimed authentic by the eminent art historian Abraham Bredius in 1937, and then sold for $6m (£3.3m). Van Meegeren's activities came to light after he was arrested for selling one of his "Vermeers" to Hermann Goring. After being found guilty of forgery, he died of a heart attack before his one-year prison sentence could begin.

*Elmyr de Hory (1906-1976)

De Hory was a Hungarian-born painter who, for three decades, used his extraordinary talent to forge masterpieces from some of the world's greatest artists, including Picasso, Vlaminck, Chagall, Toulouse-Lautrec, Dufy, Derain, Matisse, Degas, Bonnard, Laurencin and Modigliani. Not only did his fakes go for the highest prices on the art markets, but he managed to elude Interpol and the FBI for most of his criminal career.

*John Myatt (1945-)

Myatt is a British artist generally considered to have been the greatest art faker of the 20th century. According to police estimates, Myatt painted about 200 forgeries (including fakes of works by Renoir, Picasso and Modigliani), delivering them to an associate who sold them to London auction houses and to dealers in Paris and New York. Scotland Yard detectives arrested him in 1995. Since his release from prison in 2000 (having served four months of a one-year sentence), Myatt has made a successful career as an artist in his own right and his paintings now sell for up to £50,000.