They analyzed dirt on walls. They spent months trying to find the correct polish for bronze banisters and ended up producing a new formula.
They're not going to blast the vulnerable sandstone walls with high- pressure hoses this time. No, this time they'll apply scientifically formulated washes and "poultices" that will gently "suck" the grime out of the walls.
The two areas receiving the high-priced, high-tech cleanup are the east portal - the City Hall entranceway across from Wanamaker's - and the northeast stairwell.
"These will be demonstration projects to show what City Hall can look like when everything is cleaned and restored," explains Joe Martz, deputy city commissioner of public property.
The goal is have the world's tallest building without a steel frame in tip- top condition by 2001, the centennial of its completion after 30 years of construction. "For an expenditure of $150 million you have a building worth several billions," says Martz.
The $150 million is a "guesstimate" based on the ongoing renovation master plan being drawn up by the Vitetta Group.
Even if the city had billions, there's no way it could reproduce City Hall. They just don't make them like that anymore. An example is those four magnificent stairwells that rise six stories in each corner of the hall.
Each step is nearly 6 feet wide. Each flight of nine steps was carved out of a single massive block of New England granite. Amazingly, the stairs are cantilevered into the walls.
More impressive are the bronze hand railings that are each worth a fortune.
"The bronze railings were designed by Alexander Milne Calder," says art
conservator Virginia Naude, who studied the stairwells for several months. ''They were made in the 1880s by the renown Henry Bonnard Foundry of New York City, which made all the best bronze statues of that time."