Curator of an urban canvas

Rembrandt has strange neighbors here: a cartoonish, gun-toting kid in baggy clothes, a psychedelic face melting into a wall, a bare-shouldered samurai girl with vampire teeth. Perhaps the Shakespeare look-alike would comfort the Dutch master – except the bard's image turns out to be a devilish red mask.

Welcome to what some consider the world's "graffiti mecca," where aerosol artists – their preferred term – come from all over the globe to paint the walls of this 200,000-square-foot warehouse in Queens. As the No. 7 subway thunders by 20 feet overhead, tourists and locals stroll around, sometimes for hours, cameras in hand and mouths agape. 5 Pointz, named for New York's five boroughs, is the biggest space in the city where aerosol artists can paint legally – as long as they pass muster with veteran graffiti artist Jonathan Cohen. Think of him as the volunteer curator of an outdoor art gallery, one where paint comes in spray cans, the canvas is cement, and artists are more likely to be blasting hip-hop then Haydn.

On any given day, someone is usually painting. But on the weekends, 5 Pointz buzzes. Twenty or more artists, dressed in baggy jeans and T-shirts, spray walls and crevices of the giant U-shaped building that houses artists' studios and garment manufacturers. They bring supplies, snacks, even their kids. If they're not painting, they're talking, getting acquainted with new talent or artists they've admired for decades.

Want to paint? Get permission. Dozens of spray-painted signs say to e-mail "Meres" – Mr. Cohen's "tag," or signature – for a permit. He asks artists he's not familiar with to show him sketches or photos of their work and, for big murals, a layout. He tells artists that he expects a lot from them and reminds them of how many people will see their work – and he prides himself on the results. "I could sell ice to an Eskimo," he says, smiling. Cohen believes that since he took over in 2002 from another volunteer supervisor, the quality of work has vastly improved. The warehouse owner, meanwhile, gets his building freshly painted daily – for free.

There's an egalitarian ethic here ... kind of.

"Anyone can paint," says Cohen. But not everyone's art stays up for long. Some works last 12 hours; other pieces remain for two years. The determining formula is "skill level times effort times concept."

This algebra of aesthetics is far removed from the simple awe of Cohen's early encounters with aerosol art. He still recalls books of subway graffiti and seeing a graffitied Smurf on a wall as a child. His reaction? "Yo, that's fresh!"

But his adoptive parents weren't wild about his new hobby. "'This is crap,'" Cohen recalls his father saying, while his mother pleaded with him, "'Just don't get arrested."

By age 17, he had sold a few paintings and dropped out of school. He later attended a GED program in the Bronx for young people passionate about aerosol art, and then enrolled at the Fashion Institute of Technology, where he studied on-and-off for eight years while working full-time as a Manhattan bike messenger. He never graduated.

These days, the thin-faced, hazel-eyed Cohen is always on call, which may explain why his five o'clock shadow is closer to 10 o'clock. When he's not answering his cellphone or making sure the building isn't tagged illegally, he gives tours to interested onlookers. And every Sunday afternoon he teaches aerosol art to a class of 10 kids – after they earn their keep with two hours of scraping walls, painting them, and picking up trash.

Listen in on the class, and you'd swear you were hearing a foreign language. Some translations, then: a "tag" is an artist's basic signature; a "piece" is a signature with a detailed font and colors; and a "production" or "mural" is a scene with a concept.

On a recent muggy Friday afternoon at 5 Pointz, this dialect was in full force as old-school graffiti artists reminisced. Louie Gasparro (aka KR1), who has made aerosol art since 1977 as an 11-year-old tagging trains and alleys, remembers when he could tell what borough he was in by the graffiti style. Now, he says, styles from all over the world fuse into one another.

"Back in the day, you couldn't do elaborate pieces like this," says Mr. Gasparro in a thick New York accent, pointing to works that took weeks to create. As graffiti has become more accepted at places like 5 Pointz, he says, it's improved because artists can paint without the fear of being fined or chased by police. Instead of minutes, they can dedicate days, weeks, or months to a single work. But 5 Pointz is the exception, not the rule. "There should be more places like this," says Gasparro.

"It's another world away from the world," says Cohen.

Yet part of the appeal of 5 Pointz is its lack of isolation: The fact that this world is clearly visible from the subway ensures a steady flow of curious eyes. And there's another magnet nearby. P.S.1 Contemporary Art Center, an affiliate of the Museum of Modern Art in Manhattan, is across the street. When people, especially those in their 20s and 30s, unexpectedly see 5 Pointz on the way to or from the museum, they are inexorably drawn to it by a mixed sense of enchantment and disbelief. A common reaction of passersby, says Cohen, is, "'Wow! Did you do all this with a can?'"

"It brings an audience that wouldn't be coming around here otherwise," he explains.

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Last December, Cohen got a call from someone representing Joss Stone, the popular R&B singer. Ms. Stone wanted to use 5 Pointz as the backdrop for the music video of her song "Tell Me 'Bout It." Cohen had no idea who she was, but after talking to her, he gave her crew the go-ahead. He even did a mural of Stone's face for the video, in which he appears at the end.

Cohen also flew to Los Angeles to paint Stone's body for the cover of her latest album, "Introducing Joss Stone." He had never used powdery body paint before or painted anyone's entire body, but "I'll never turn down a job," he says.

This motto has led him to accept corporate work, too – an opportunity that might not have been conceivable in the early days of aerosol art. On that same muggy Friday that the old-school artists were painting at 5 Pointz, Cohen was in Brooklyn working on a mural that advertises iced tea. He does corporate gigs purely for the money, he says, but dismisses any talk of "selling out."

"I couldn't work a regular job and work 5 Pointz," he says. When he's not at a gig, he's volunteering his time there, and although he gets paid for commercial use of 5 Pointz for film or photography, he says he annually spends $10,000 of his own money on the building.

"He spends his life there and he doesn't get much for it," said Ms. Stone, the R&B artist. "It's all about the love for the art."

Money aside, Cohen has big dreams for 5 Pointz. He wants to open an aerosol art clothing and supply store, a museum, and an art school. Money considered, he realizes these dreams will cost a lot. "I take it year by year," he says.