A lengthy investigation conducted by the National Gallery of Art in Washington, D.C., into four paintings by and attributed to Johannes Vermeer has wrapped, and its findings will be the subject of an exhibition this October.

That NGA show, titled “Vermeer’s Secrets”, will present two works from the museum’s collection whose authenticity have been questioned—Girl with a Red HatandGirl with a Flute(ca. 1665–75)—and two that have been accepted as Vermeer originals. Two 20th-century forgeries were also examined. According to Marjorie Wieseman, NGA curator and head of the department of Northern European paintings, the exhibition aims to discover “what makes a Vermeer a Vermeer”.

In 2020, the NGA took advantage of the Covid-19 closure to move the four works, which are rarely taken from public view, to the museum’s conservation studio. There, advanced imaging techniques virtually penetrated layers of paint in combination with a microscopic examination of the paintings’ surfaces to analyze Vermeer’s process.

Along the way, researchers discovered that Girl with a Red Hat once had a different composition. It was originally a portrait of a man, which Vermeer later reimagined as a girl. This is surprising, given that few of the Flemish artist’s paintings are considered true portraits, and he preferred to depict women in moments of motion or contemplation.

Girl with a Flutehas been suggested to be an original painting by Vermeer. It was discovered in 1906 and donated to the NGA by Joseph Widener in 1942. The authenticity of the work was challenged by the influential Vermeer scholar Pieter Swillens in 1950, and successive experts embraced his position.

In the 1990s, the NGA’s curator and Vermeer specialist Arthur Wheelock even questioned the painting, leading to its designation as “attributed to Vermeer.” Following his retirement in 2018, Wheelock changed his stance: “I have concluded that removing theGirl with a Flutefrom Vermeer’s oeuvre was too extreme given the complex conservation issues surrounding this image,”he wrotein the NGA’s online catalog entry on the painting.

A final ruling on the painting’s authenticity will be shared ahead of the exhibition’s opening on October 8.

Also on display in the exhibition will be the NGA’s accepted Vermeers:Woman Holding a Balance(ca. 1664) andA Lady Writing(ca. 1665). Chemical imaging of the lower layers of the former painting revealed quick, spontaneous, and textured brushstrokes—shockingly different from the finished composition, where individual brushstrokes blend into a smooth surface. “This discovery brings into question the common assumption that the artist was a painstakingly slow perfectionist,” NGA said in a statement.

Two obvious forgeries will be displayed beside the four Vermeers in the Washington, DC exhibition:The Lacemaker, a loose interpretation of the 1669-1970 original in the Louvre in Paris, andThe Smiling Girl. Both forgeries are believed to have been created around 1925 and were bequeathed to the NGA by Andrew Mellon in 1937. They were deemed imitations by the NGA in the 1980s.

All four paintings will traveltotheRijksmuseumin Amsterdam for a Vermeer retrospective after the closure of the NGA exhibition on January 8, 2023.