Museums and collectors need the services of art authenticators because, as the late art authenticator and microscopic analysis expert Walter McCrone wrote, copying and fakery are among the art world’s most ancient traditions, dating back to the Phoenicians’ counterfeit Egyptian pottery and the Roman forgers who churned out copies of coveted Greek paintings and sculptures. The myriad Italian Renaissance forgers included Michelangelo himself, who as a youth sculpted a sleeping cupid, treated it with acidic earth to simulate the appearance of an antiquity, and then sold it through a dealer to a cardinal. (When the fraud was discovered, the cleric actually let Michelangelo keep his percentage of the sale, because his sculpting was so impressive.) By the 18th century, according to McCrone, art fraud had evolved into a highly sophisticated profession, with forgers baking their canvases in ovens and mixing chimney soot into their paints in order to simulate the effects of age. (Some fakers even went through the charade of restoring the intentionally damaged paintings.)

In the 1930s and 1940s, Dutch painter Henricus Antonius van Meegeren — perhaps the most infamous art forger of all time — set out to embarrass the critics who’d snubbed his own work by creating a series of paintings in the style of 17th-century master Johannes Vermeer, and then passing them off as the real thing. Sure enough, the arbiters of taste praised the "lost" Vermeers, and collectors were willing to pay hefty sums for the fakes, because van Meegeren was no ordinary crook. He spent years developing a method for applying phenol and formaldehyde to paint to simulate aging, and even used the same sort of brushes as Vermeer in order to more faithfully replicate his technique.

Such fakery continues to this day. Thomas Hoving, former director of the Metropolitan Museum of Art in New York, once estimated that 40 percent of the artworks on the market were either outright fakes or "half-forgeries," paintings by obscure artists that have been altered to make it appear that someone famous created them. Art forgery has grown so audacious that some even dare to counterfeit relatively recent artists. In the 1990s, a high-profile auction of works supposedly by artists such as Jasper Johns and Georgia O’Keefe had to be cancelled, after authenticators exposed them as forgeries. In January 2006, a painting attributed to Andy Warhol, valued at nearly $2.6 million, became worthless when a board of art authenticators challenged its genuineness.