It's water.

"With enough water, you can get even the worst sand to work for you," says Oakland's Kirk Rademaker.

As possibly the Bay Area's only professional sand sculptor, Rademaker knows his sand and he makes a living from an office most of us could only dream of: the beach of the Pacific Ocean.

In fact, he says he knows "every beach from Big Sur to Bodega," and he certainly has his favorites for building sand sculptures: Pajaro Dunes south of Santa Cruz, and Doran Beach in Sonoma County.

He discovered his calling in 1997 during a "bad spell" in his life.

"I would go to Stinson Beach to just be by myself, and to sort things out," he says. "I started building sandcastles, and it was amazing how therapeutic that could be."

The best thing, he says, is that it's a social activity. "Everybody came up and talked to me about what you're building, so I didn't feel as lonely."

He found other sand enthusiasts, and became part of a network of sculptors who participate in sandcastle competitions worldwide. He discovered that he was able to tap into a market of people who wanted to pay for the chance to learn how to build sandcastles. Add to that kids' birthday parties, corporate team-building events and educational programs, and he'd sculpted a living for himself.

He's also reaped some unexpected benefits along the way, doing private parties for Hollywood stars, as well as holiday events for the LucasFilm folks.

On this sunny Friday, he isn't on a beach but outside the Lawrence Hall of Science in the Berkeley hills, crafting a 5-foot castle as part of a weekend program. Just as he said, the activity draws curious onlookers of all ages. The castle is halfway finished, but already it has some of the younger crowd wondering.

"Is that Cinderella's castle, or the one from 'Beauty and the Beast'?" asks one young girl.

"Neither -- it's from my imagination," Rademaker says.

But believe it or not, he doesn't enjoy making castles. He prefers elaborate mechanical shapes, but decided that the sand at hand -- which was delivered sort of rocky -- could be put to better use as a medieval castle.

"I'm a sand snob," he says. "But I make it work."

Spoken like a true artist.