Had it been a normal October, the big attraction of the Philadelphia Open Studio Tour on Saturday would have been the artist hive at 915 Spring Garden, the massive redbrick Reading Railroad train station hard by the abandoned viaduct.

But this is far from a normal year for Philadelphia's stalwart artists' community. After city building inspectors discovered a host of safety violations at the century-old depot last month, more than a hundred artists found themselves out on the street. They were scratched from this year's open house, an important showcase for emerging artists. Most were too busy, anyway, searching for an affordable spot in one of the dwindling number of gritty industrial buildings in the city's core, traditionally havens for artists.

So, it was the tight market for artist studios - and not the art that gets made there - that was the talk of Saturday's open house. This was especially true at 1241 Carpenter, among the last surviving artist buildings and, by default, the premier stop on the tour.

"There's a waiting list for this building," said Tim McFarlane, 50, a painter who scored a closet-size studio there in August after a rent increase forced him to abandon a loft in Old City. At half the size of his previous studio, he had to pack it with floor-to-ceiling shelving to hold his paints and brushes, leaving just a canvas-size work area. Still, he's grateful.

The closing of the Spring Garden studios and the diaspora of artists it unleashed, he said, is the latest sign of Center City's profound transformation into an island of privilege.

"Artists are like the canary in the coal mine," McFarlane explained. "They're moving farther and farther out. I was in the Goldtex building before Old City," but that got turned into luxury apartments.

If the real estate boom keeps going at this pace, he worries that there may come a day when there are no artist buildings left in between Spring Garden and Callowhill, the focus area for Saturday's open house tours. (Next Saturday, the tour moves west of Broad Street.)

The building survives as an artists' enclave primarily because its owner, the inventor Steve Krupnick, has a soft spot for the creative community. He bought the building in the '70s, when 12th and Carpenter seemed a world away from glittering Center City, and now owns it debt-free. Yet, not a week goes by, Krupnick said, when he doesn't get an offer on the property from a developer.

Best known for inventing the FlippyFlyer, a sort of soft Frisbee, he has refused them all. "It's just a lot more fun to have a building filled with artists," Krupnick said. But how long he can hold out is unclear, especially given that Bart Blatstein is planning a massive apartment-and-retail complex one block away, at Broad and Washington.

Stella Gassaway, a printmaker who has a spacious studio on the third floor, considers Krupnick "the landlord from heaven." It was never his plan to turn the building, which originally housed a conveyor-belt factory, into artist lofts. But every time an artist knocked at his door, he found a way to convert another room into a studio. Toilets and sinks are down the hall.

The ceramicist Peter Cunicelli, a refugee from Spring Garden, looked around enviously at Gassaway's studio. He had stopped by for the open house because he needs to find a new studio and wanted to see how the artists at 1241 set up their work space.

Gassaway said it's not just studio space that's being lost as prices force artists into new territory far from Center City; it's also the sense of community that comes with being in a building packed with creative hands.

Some artists who were showing their work in the common gallery at 1241 said they've abandoned the idea of artist communities altogether. Collette Fu recently moved into a new apartment where she can also work on her pop-up art books. "Now my studio is my dining-room table," said Fu.