Rothko’s Black on Maroon, 1958—part of the artist’s much-admired series of paintings known as the “Seagram Murals”—went back on display at Tate Modern last month, 20 months after it was defaced with graffiti ink in 2012. The nine-month treatment took place after nine months of research, tests and consultation with the artist’s family and international experts, including Jay Krueger, the Modern paintings conservator at the National Gallery of Art in Washington, DC. A lack of prior knowledge of the graffiti ink and the complexity of Rothko’s paint layers made the project particularly challenging, says Bronwyn Ormsby, the Tate’s conservation scientist. A special solvent—a blend of benzyl alcohol and ethyl lactate—was used to remove the ink, and conservation-grade materials were used to restore the painting’s surface. The Tate’s director, Nicholas Serota, says he is most proud that, despite the extensive treatment, “we didn’t have to remove any of Rothko’s paint… what you see is [his] paint”.