Experts pour scorn on Pollock finds after tests

Fresh doubt has been cast on the authenticity of 32 recently discovered Jackson Pollock paintings by researchers at Harvard University who now say that some of the paint pigments used were not available until after the artist's death in 1956 in a car crash on Long Island.

The team at Harvard's Straus Centre for Conservation issued a report after submitting a sample of three of the trove of works to a full year of painstaking analysis. In it they stop short of calling them fakes but leave little reason for confidence that they are in fact the product of Pollock's troubled genius.

Their findings add another twist to a saga of claims and counterclaims about the paintings that is fast becoming as tangled and impenetrable as the squiggled masterworks that made Pollock so famous.

Certainly, it is not encouraging news for Alex Matter, who first revealed in 2003 that he had found the 32 pictures in a storage locker on Long Island that had belonged to his late father, Herb Matter, a photographer who had been a close friend of Pollock and his wife, Lee Krasner.

What he had found looked to be the genuine article and the art world erupted with joy. Though mostly small in scale - unlike the huge 4ft-by-8ft Pollock that sold for a record $140m (£71m) at auction in New York last November - they all shared the unmistakable style of the artist, whose pioneering drip-paint abstract modernism prompted Time magazine to christen him "Jack the Dripper". But no one stumbles upon treasure of such potential worth without being asked for proof of authenticity. Thus, Mr Matter recruited Ellen Landau of Case Western Reserve University in Cleveland, a respected Pollock scholar; she declared the works genuine. Ms Landau's judgement waschallenged, including by the Pollock estate represented by the Krasner Pollock Foundation. And so Mr Matter agreed to submit the sample of three works for analysis at Harvard. He had hoped they would clear up any lingering doubts.

On the contrary, the Harvard study reveals numerous new problems. For example, on one painting researchers found a red paint that "has only been marketed for a few decades" and a brown paint not developed until the early 1980s, whereas the paintings had been traced to a period between 1946 and 1949.

Mr Matter now suggests we do not put too much store in Harvard scientists. "The authentication of works of art is still more art than science," he said. "The point is that the science of attribution is still in flux, and no scientific test is definitive in the absence of traditional, time-tested art historical research." He points out that restoration work and varnish applied to the paintings may have muddied the findings.

All of which has led Narayan Khandekar, the head researcher on the team, to join the debate. "You can't just dismiss this one piece of evidence. That's not the right way to approach a scholarly discussion," he offered. "You have to have an art historian and a connoisseur who uses his or her eye and the scientist has to play a role in that," Mr Khandekar added. He saidthe evidence suggestedthe pictures were altered after Pollock's death.

Mr Matter may be beginning to feel like Teri Horton, a retired lorry driver who has spent years trying to persuade art scholars that a painting he bought for $5 is also a Pollock. Mr Horton is the star of a recently released documentary film, Who the #$&% is Jackson Pollock?