Judging by the relentless wooooossshing sound around him, Richard Novicki could have been standing in the wilderness next to a geyser.

In fact, he was in the heart of the University of Pittsburgh campus. And the noise that all but drowned out his voice was that of history being undone, one blackened stone at a time.

Above him, work crews with hoses blasted a pressurized mix of water and recycled powdered glass against Pitt's landmark Cathedral of Learning, a process that is returning its massive exterior to a look resembling what it was when the Indiana limestone building in Oakland was completed in 1937 after 11 years of construction.

	Darrell Sapp, Post-Gazette Workers get set in one of the enclosed patios of the Cathedral of Learning Click photo for larger image.

"Eighty years of soot from the mills, from buses and cars,'' said Mr. Novicki, a foreman for Pittsburgh-based Cost Co., which is doing the work this spring and summer. "All of it, washed away in seconds."

The cleaning and restoration of Pitt's signature 42-story skyscraper, the tallest classroom building in the Western Hemisphere, began in March and will run until the end of September. Already, change is visible as crews move about scaffolding on the 535-foot tower, the sound of their methodical work echoing in the breeze.

Cost Co., selected by Pitt, studied the Cathedral for seven years to find a process that fit the building's design. The chosen method has been used on the likes of Buckingham Palace in Great Britain, the Kremlin in Russia and St. Peter's Basilica in the Vatican.

Working from 6 a.m. to 5 p.m. weekdays and eight hours on Saturdays, crews are taking pains not to disturb a pair of peregrine falcons nesting on the 40th floor ledge, said Charles "Corky" Cost, owner and chief executive officer of Cost and a Pitt graduate.

"We've been working just the low areas while they are taking care of their young ones," he said.

After June 21, crews plan to start moving into higher areas.

Sixteen hoses were trained on the building simultaneously one afternoon this week. That number will grow to 24 as the project progresses, Mr. Cost said.

		Listen In PG reporter Bill Schackner talks with Bob Sabo, one of the workers cleaning the Cathedral of Learning and also Cost. Co. owner and CEO Charles "Corky" Cost as he describes the process developed for the Cathedral project. Bob Sabo talks about the cleaning and restoration process. explains the process used to clean the stones. how to clean the stones with indentations without damaging them. Charles "Corky" Cost, owner and CEO of Cost Co., describes the process developed for the Cathedral project.

Ordinary business in the Cathedral has continued largely unaffected, save the hissing sound reverberating through some classrooms and the occasional sight of men in hard hats and rain gear near windows. When cleaning moves to a particular floor, office workers are alerted in advance and asked to make sure windows are sealed.

Some 11,700 students and workers are in the Cathedral daily during the school year, but a noticeably lighter crowd this week seemed unfazed by the noise.

"It think it's great," said Michaelangelo Tabone, 20, a junior engineering major from Buffalo who was studying inside. "It's nice to see it being cleaned."

The now familiar two-tone effect running down the Cathedral's sides is a reminder of Pittsburgh's smoky steel days.

But as sooty buildings go, Mr. Cost said, things could be worse.

"If this building was in Los Angeles it would be a lot darker with a lot more soot on it from the environmentals and the smog and all that," he said.

The closing of the steel mills accelerated the natural cleaning that occurs from Pennsylvania's freeze-thaw cycles and approaching weather fronts, Mr. Cost said.

Even so, removing what's still stuck to the building is no small task.

Before applying pressurized water and powdered glass to the soiled stones, workers douse them with running water from soaking hoses for two or three days round-the-clock to loosen deposits, a bit like soaking a heavily soiled garment before washing it.

Sediment washes down the building and settles on the ground. From there, it is carted away.

The Cathedral's exterior is laden with residue of carbons, sulfur dioxides and gypsum. The deposits, if not removed, will further erode the building's architecture as they capture moisture.

But the work involves more than cleaning. As part of the project, cracked stones and loose or missing mortar are being fixed in hundreds of locations.

"This building is a jewel," Mr. Cost said. "When you see this thing finished, it's going to look outstanding."

Pitt trustees approved the $4.8 million project in February. University reserve funds are paying for the work as donors are solicited through Pitt's $2 billion "Discover a World of Possibilities" fund-raising campaign.

Bob Sabo, 56, of Bethel Park, one of those hosing down the building this week, said working hundreds of feet in the air is nothing unusual and that his 30 years on the job have taken him to such heights as the top beam of Fifth Avenue Place, Downtown.

Even so, he and other workers leave little to chance. They are covered from head to toe in rain gear, boots and a hard hat, plus ear muffs, glasses, breathing apparatus and a harness.

"You've got to respect it," Mr. Sabo said of the height.

"You try to clean it as best you can without damaging the stone," he said of the Cathedral work.

"What you try to do is go across. If the joints go vertical, you go vertical. If the joint goes horizontal, you go horizontal."

The Cathedral project hits close to home for Mr. Cost, a member of Pitt's Class of 1958 and a running back on the football team.

He remembers peering at the soot decades earlier when entering the Cathedral as an undergraduate.

"I'd look up and say 'One of these days, I'm going to clean this,'" he said. "That was 40 or 50 years ago. It took a long time for it to come true."