The Guardian gave art historian Martin Kemp a platform to express his own consternation with the state of authentication:

The uncovering of fakes by committees comprising descendants of the artist is increasingly common and has prompted one of Britain’s foremost art historians to condemn the methods used by scholars to authenticate works as a “professional disgrace”.

Martin Kemp, emeritus professor of art history at Oxford University and a Leonardo expert, said many rely on “dubious data” and that a “chaotic” approach is used to attribute paintings. He said he was alarmed at the ease with which historical, visual and scientific evidence is manipulated to suit the overriding objective – enhancing academic reputations or boosting financial rewards in attributing paintings to particular masters.

“There’s lots going on, from academic incompetence to really dirty stuff,” he said. […] He is alarmed by owners and syndicates of investors, with much to gain from a painting’s attribution to a master, who commission tests on pictures with a “visual plausibility” and censor data that fails to back their case. If, for example, a report casts doubt on a Rembrandt attribution because tests reveal a pigment only developed after the artist’s death, contracts prevent the report’s author from speaking out if that information is suppressed. Kemp said: “There has certainly been some legal silencing.” He observed that few art experts can stand up to “fancy lawyers” employed by owners, “bullying of the worst kind”.

Money is the motivation, he said. As pictures change hands, he is sometimes sent the same picture – at about five-year intervals – by each new owner. He said: “The syndicate get a few opinions from some more easily manipulated art historians. They assemble a body of scientific data, sell the picture for a profit to the next syndicate, upping the ante each time.”

[…] Nicholas Eastaugh, scientist and technical art historian of Art Access & Research, whose clients include leading auction houses, said: “There are no standards. It’s totally unregulated. It’s a Wild West … We’re trying very hard to establish standards, but there is no professional control. You can shop around for a scientific report that probably says essentially what you want. It’s shocking.”

Revealed: the art experts who pass fakes as authentic (The Guardian)