Brian Ramnarine, 59, pleaded guilty to three counts of wire fraud in Manhattan federal court. He acknowledged that he had falsely claimed that the artists had authenticated the sculptures that prosecutors said he created from molds he kept after being paid by the artists to do work.
U.S. District Judge John G. Koeltl asked him if he knew what he was doing was wrong and illegal when he committed the crimes.
"Yes, your honor," Ramnarine answered.
Ramnarine's skills with liquid metal made him a favorite of artists in the 1980s and early 1990s, and Johns conceded that he had used him several times because of his excellent work.
Ramnarine agreed not to challenge any sentence of 10 years or less in prison as part of a plea deal. The wire fraud charges otherwise carry a potential of 60 years in prison, and Ramnarine could face another 20 years in prison because he admitted carrying out additional sculpture frauds after his arrest.
Sentencing was set for May 30.
Ramnarine admitted falsely telling prospective buyers that the works he was offering from Johns and two other artists were legitimate.
Johns testified last week that the sculptures of "Flag" offered by Ramnarine were fakes.
Johns, 83, was the star witness for prosecutors trying to prove Ramnarine tried to sell an unauthorized bronze sculpture of the painting in 2010. Four bronze copies of "Flag" were made in 1960, and the jury was shown a picture of President John F. Kennedy posing with one that was given to him.
The Sharon, Conn., artist said he went to Ramnarine in 1990 and asked him to create a wax mold because he was considering making a gold sculpture of "Flag" from a wax mold. He said he didn't believe he had spoken with Ramnarine since 1990 and wasn't friends with him.
Johns chuckled when a prosecutor asked him if he ever gave Ramnarine a copy of a painting that was sold to the Metropolitan Museum of Art for millions of dollars.