PHILADELPHIA—Laser technology is being used to remove a century of grime from eight statues that ring City Hall's tower, the latest phase of a 10-year project to clean the massive building's exterior.

The statues, installed in the mid-1890s, are among 250 bronze figures at City Hall designed by famed sculptor Alexander Milne Calder.

Cleaning with lasers is a tedious process, but also a clean one workers burn the dirt off, instead of letting it fall down the side of the building.

"In Europe, they've used lasers to treat and clean smaller sculptures, but nothing as big as the sculptures on top of City Hall," said Andrzej Dajnowski, director of the Chicago-based Conservation of Sculpture & Objects Studio Inc., which is doing the work.

As they work, Dajnowski and his crew are also replacing thousands of rotting screws and washers in the statues, which weigh about 25,000 pounds each and are at least 24 feet high. The symbolic figures include an American Indian warrior with a wolf-like animal and a Swedish woman with a child and a lamb.

"It's like cleaning the sculpture with a pencil eraser," said George Hee, the city fiscal officer overseeing the $1.4 million laser project. "You have to do it spot by spot by spot."

Calder also designed the building's most famous feature, the 37-foot high statue of William Penn that stands atop the Second French Empire building.

Philadelphia's City Hall is said to be the nation's largest municipal building, and was the tallest occupied building in the country until 1909, when the Metropolitan Life Building in New York was built.

Barry Dornfeld, a documentary filmmaker, is recording the cleaning process for a University of the Arts project.

"As a solution to the problem of how to clean these things, the lasers are kind of amazing," Dornfeld said. "I'm curious to see the before and after."
Copyright 2005 AP
Photo: Jacqueline Larma/AP Photo