The New York Times gets the details on Rockefeller Center’s project to restore the Jose Maria Sert murals that decorate the main building of the complex:

When the murals in the north corridor of 30 Rockefeller’s lobby were finally cleaned, Jeffrey Greene, EverGreene’s president, had a eureka moment. “I realized the building was out of balance,” he said one recent steamy morning, standing on a second-floor balcony and staring directly into “Abolition of War,” a mural by the Spanish painter José María Sert that depicts a woman astride two cannons with a baby in her outstretched arms.

When Rockefeller Center was built (it was conceived in 1930 and finished nine years later), “the marble was supposed to have the same tonalities as the background color of the walls and the murals,” Mr. Greene said.

During construction, Edward Trumbull, a painter, designer and muralist, coordinated the color schemes of all the artwork and the finishes for the lobbies of every building in the complex. But over the years the surfaces grew darker. And as the murals’ topcoat of varnish deepened, the maintenance staff painted the undecorated parts of the walls a darker color to match. After the north corridor lobby murals were cleaned, Mr. Greene discovered that the color scheme for the whole interior was out of whack.

The murals “were supposed to be in harmony with the warm, stone color of the marble,” he explained. With the cleaning, he added, “it was as though we’d switched on the lights.”

The ravages of age became apparent in other ways, too. For example, over the years the baby in “Abolition of War” had been obscured and looked like a blemish.

Two years ago, when Tishman Speyer, co-owner and manager of Rockefeller Center, hired EverGreene, Mr. Greene spent six months doing nothing but research. “I read the Rockefeller family archives,” he said. (Robert J. Speyer, senior managing director of Tishman Speyer, would not specify the project’s cost, although it is believed to exceed seven figures.)

Stripping Away the Darkness as Murals are Reborn (New York Times)