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Of time and treasure
PROSOCO and the Cleveland Museum of Art

From ancient armor to modern sculpture, the Cleveland Museum of Art displays centuries of time's treasures. Yet perhaps the most fabulous artifact of all is the original 1916 marble building housing them.

It's been described as a "treasure box," and even as "a temple on a hill," says Randall Von Ryan, AIA, the museum's associate director of architecture and construction. Mr. Von Ryan served as project director for the building's four-year exterior restoration, completed in 2002.

Built of Georgia white and Cherokee marbles, the neoclassic structure is the centerpiece of a four-building museum complex. The museum and its marble terraces sit astride a grassy hill surrounded by trees, sculpture gardens, and fronted on its southern facade by a 13-acre park designed by the Olmsted brothers in 1928.

The $12.4 million three-phase project started with cleaning and repairing the "temple" exterior. Workers then disassembled, cleaned, repaired and reassembled the marble terraces around the building. Landscaping completed the work.

Eighty-five years exposure to the harsh northern Ohio climate, combined with decades of industrial pollution had tarnished the venerable marble structure's exterior.

"In general, the marble had become gray from air pollution, with black carbon crusts on drip edges, dentils, column caps and bases, and ornamentation," recalled Hyman Myers of VITETTA, the Philadelphia-based firm that handled the restoration.

Mr. Myers, chief restoration architect on the project; and VITETTA's masonry specialist, Nan Gutterman, at first chose the JOS System to clean the stained stone.

The JOS System is a French micro-abrasive cleaning method combining air, water and powder in a swirling low-pressure vortex that gently scours contaminants off stone.

"We'd had success with JOS on other projects," said Ms. Gutterman. She noted the system worked well in tests on the museum portico and low areas of the exterior walls.

But when crews from masonry contractor Graciano Corporation, Pittsburgh, Pa., hit the walls top to bottom, the JOS vortex was ineffective.

"It wasn't cleaning the main part of the wall," Mr. Myers said. "We were back to square one."

"Square one" involved an examination of the areas the JOS System failed to clean. Hand-held microscopes revealed a film on the stone.

The conservators learned that someone had put a film-forming water repellent on the stone in the late 1950s. Still well-adhered, the yellowed and dirty coating covered much of the exterior.

"We called PROSOCO because they're always ready to help at a moment's notice," Mr. Myers said. PROSOCO manufacturer's representatives Wil Priver of Wil Priver & Associates, Bay Village, Ohio; and Jan Hawkins of Technical Marketing Services, Hudson, Ohio, answered the call.

"First we tried paint strippers, which didn't work," Mr. Meyers recalled. The results came with Sure KleanŽ 766 Limestone & Masonry Prewash, followed by Sure KleanŽ Light Duty Restoration Cleaner.

The alkaline prewash dissolved carbon crusts and other deep-seated contaminants without harming the sensitive marble. Where the film overlaid the marble, 766 dissolved contaminants on the film, for easy rinsing away.

The afterwash with Light Duty Restoration Cleaner neutralized any remaining alkalinity from the prewash. It heightened the cleaning effect and brightened the stone, even in the areas where the film remained on the surface.

The two-step method cleaned about 60,000 square feet of sensitive marble, estimated Dave Sinclair, Graciano project manager.

"We did 50 different mockups before we got what we wanted," he said. "But the building looked great when we were done."

Next, the conservators set to cleaning and repairing the museum's marble terraces and balustrades. In some places the balustrades were tilting and the marble blocks were out of joint, Mr. Von Ryan recalled.

Temporary wood shoring held several lengths of balustrade from toppling over.

One of the problems VITETTA recognized was no drainage. Decades of water with no place to go had penetrated the marble and undermined the terraces. Project Manager Len Verdell, Jance Construction llc., Mentor, Ohio, oversaw the massive effort of disassembling the terraces and the pouring of new foundations (with drainage, this time).

The project involved taking apart and labeling 3,500 tons of marble blocks. The 3,000 blocks of stone ranged from 300 pounds to the 15,000 pound pedestal of Rodin's Thinker, perched outside the museum's south main entrance.

Scot Stone Inc., Cleveland, reassembled the terrace and then workers from Coon Caulking & Restoration, Louisville, Ohio cleaned the entire terrace, once again using Sure KleanŽ 766 Limestone and Masonry Prewash. In this phase, the crews followed the Prewash with Sure KleanŽ Limestone & Masonry Afterwash.

"It was a huge job, but it came out beautifully," Mr. Verdell commented.

As visitors (about 500,000 a year) again began to arrive, so did the preservation awards - four so far.

In April, the International Masonry Institute gave the museum its prestigious "2003 Golden Trowel Award" - fitting tribute, perhaps, to a building itself dedicated to preserving time's own treasures.