By CHARLES McGRATH

Julian Schnabel paints portraits the way the old masters did, starting with a dark background and then layering on light and color. Where the masters varnished their pictures, Mr. Schnabel sometimes coats his with resin. The main difference is that the old masters took weeks or even months to complete a portrait, and Mr. Schnabel can finish one in several hours, which, even allowing for several centuries’ worth of inflation, makes for a much nicer payday.
Recently, he was at work painting Placido Domingo. The portrait was commissioned by the Metropolitan Opera to commemorate the anniversary of that tenor’s Met debut, and is to be unveiled at a gala there on September 28, 40 years to the day after Mr. Domingo, then 27, stepped in for an ailing Franco Corelli and sang the role of Maurizio in “Adriana Lecouvreur.”
“Most tenors don’t last 14 years, let alone 40,” said Peter Gelb, the general manager of the Met. “We were just trying to think of an appropriate way to honor a career of such duration and excellence.”
He added: “The Met has a long history of very large and not necessarily wellpainted portraits of singers in costume. Some of them are quite good, but some are the painting equivalent of what you’d see in a wax museum.”
Mr. Domingo was patient and relaxed, giving no indication that he leads a whirlwind life . Not only has he sung more roles, and sung them better, than probably any tenor in history, but at an age when most singers have begun to trim their repertory, he is also still expanding his. He runs two companies, the Los Angeles Opera and Washington National Opera, and in his spare time he conducts.
“My secret is that I enjoy so much what I’m doing, he said. “Yes, sometimes one gets tired, but my work also gives me so much energy.”
Mr. Schnabel, 56, is also a singer of sorts, and in the ‘90s recorded a rock album, “Every Silver Lining Has a Cloud.” More recently he has directed prizewinning films like “The Diving Bell and the Butterfly. But Mr. Schnabel, who once said of himself, “I’m the closest you’ll get to Picasso in this life,” remains a painter of prodigious energy, productivity and selfconfidence.
A couple of days before painting Mr. Domingo, Mr. Schnabel sorted through the summer’s work with the help of some black-clad assistants .
There were dozens of paintings, most of them huge, and most made from photographs or from some antique French hospital X-rays that had been blown up on canvas and then Schnabelized with ink, paint, resin and blobs of gesso.
About painting portraits, he said: “I never paint from photographs. The idea of accident or surprise is very much a part of it. I’m putting myself where there’s no guarantee of a return trip. You hope your painting looks like the subject, and mine seem to do that. When I paint paintings of people, I really get them. It’s very important to me to capture the soul of the person.”
He had never met Mr. Domingo, he said, adding: “I think he’s probably a good man - he has a nice face. I don’t want to paint anybody. I don’t want to paint Fidel Castro. I wouldn’t make a painting of George Bush.
For the portrait, an assistant from the Met had brought along Mr. Domingo’s Act III costume from Verdi’s “Simon Boccanegra” - tights, brocaded robe, shin guards, breastplate, gauntlets, cape.
“The tights wear out the hair on my legs,” Mr. Domingo said, wriggling into them, and after putting on the breastplate, he remarked: “Oh, it’s hotter than I remember. I thought it was just the stage lights.”
When he was done, he struck a heroic pose for Mr. Schnabel and said: “One of my strongest roles, for which I am best known, is Otello. There is also Adorno, from ‘Simon Boccanegra.’ But this could be Otello.”
Mr. Schnabel said: “I’m just going to paint you as you.” He stationed Mr. Domingo in the shadow of a pillar, explaining to him, “I like painting in oscurida, because the face comes out more,” and told an assistant to tune his iPod to some songs his daughter’s boyfriend had recorded.
Holding a cigarette in one hand, his brush in the other, Mr. Schnabel began quickly sketching in white on a brown canvas roughly two meters square.
The shape of a head emerged, a halo of hair, a glint of armor, the outline of a torso. Mr. Schnabel stepped back and ordered all bystanders to leave the studio. “I’m just painting the light in,” he said.
He started at 3:15 p.m., and at a little after 6 someone from the Met came by to collect the costume, and Mr. Domingo left for the airport. He had to be in Washington the next day for his company’s season opener, “La Traviata,” an opera about a woman who burns herself out.