The most prominent piece of public art in Portland is getting a makeover. Sculptor conservator Jonathan Taggart spent much of Monday 45 feet off the ground in Monument Square, pressure-washing guano and a decade-plus of urban grime from the surface of “Our Lady of Victories (The Portland Sailors and Soldiers Monument).”

“It’s pretty dirty up there, but we’ll get her clean,” he said back on solid ground, as he unhitched a safety harness and stepped away from a power lift that hovered over the square much of the afternoon. His long, white hair was tucked under a large hat that shielded him from the sun, and he wore heavy rubber waders to protect him from all the water.

He hopes to finish up the power-washing Tuesday and then will apply a protective resin to the bronze surfaces of the sculpture, which honors the 5,000 soldiers from Portland who died in the Civil War. At the time, the deaths represented one-sixth of Portland’s population. The sculpture was dedicated in 1891.

The monument receives conservation attention about once a decade. Taggart, who owns Taggart Objects Conservation of Georgetown, is being paid $10,000 to do the work, part of a tax-funded $25,000, two-year contract between his company and the Portland Public Art Committee to maintain the city’s public collection of art.

The collection includes a lot of monuments and statues. “Our Lady of Victories” is the most prominent. It’s at the heart of the city. Its central figure, a 14-foot female figure standing high atop a granite base, was cast by Franklin Simmons, an internationally known sculptor who lived in Italy but happened to be a Portland native. Simmons also created Portland’s Longfellow Memorial, and several of his pieces are in the collection of the Portland Museum of Art.

Taggart said the sculpture is mostly sound. The resin coating, previously applied about 12 years ago, has begun to fail on the uppermost exposed surfaces, and various mortar joints have failed. The piece also suffers from carbonate and copper staining and minor graffiti, which will be removed.

In addition to brushing on the resin coating, Taggart will repoint and repair failing joints. He described the work as routine but essential to maintain the look and integrity of the sculpture. Some areas of the sculpture, particularly on the figure’s shoulders, nose, cheeks and liberty cap, have turned a light blue-gray color. That’s a result of the failure of the previous resin coating. The cleaning and coating process will return those areas to a color more uniform with the rest of the sculpture, he said.

This is the third time since 1997 “Our Lady of Victories” has been treated with resin. For its first 100 years, there was no coating at all, Taggart said. “We have to maintain the protective coating to stop the ongoing corrosion,” he said.

The bronze female figure is a symbol of unity and is modeled after Minerva, the goddess of both wisdom and war. In one hand, she clutches a sword wrapped in a flag. In the other, she holds a shield and a branch of maple leaves.

New York architect William Morris Hunt designed the granite pedestal, which is affixed with bronze figures on two sides. One represents the Army and the other the Navy. The base is inscribed: “Portland, to her sons who died for the Union.”

Hilary Bassett, executive director of Greater Portland Landmarks, stopped by Monument Square at midday Monday to assess the progress.

“It’s important to keep an eye on it and keep up with it,” Bassett said. “It’s easy to take it for granted, because it’s always here. But we have to maintain what we have.”

Taggart attracted many onlookers. Some grumbled that their usual stoop for hanging was occupied and dripping wet, but most were content to pause, glance skyward and snap a few photos before moving on.

West End resident Fran Houston imagined that the statue smiled ever so slightly.

“I think she loved that she was being photographed,” she said.