Before NationsBank removed the giant "mn" letters last April from atop the former Maryland National Bank Building in Baltimore, its executives vowed to make the "bonnet" underneath look as good as new.

Now that the $300,000 project is complete -- including repairs to the copper shingles and a new coat of gold leaf on the "ribs" and cornice -- it is apparent the bankers weren't exactly true to their word. They made it look even better.

The restored tower at 10 Light St. -- now renamed the NationsBank Building -- never before looked the way it does today. That's because the bank and its consultants took steps to make the 60-foot-tall mansard roof stand out more than ever.

According to the hard-hat artist who applied the new gold leaf to the roof, the original material may have been as bright when the tower opened in 1929 as it is today, but it did not cover as much of the surface. And it was not set against the blue-green backdrop it has today, since it took years of oxidation for the copper shingles to acquire their patina.

In its calculated attempt to improve on the past, the bank succeeded beyond all expectations. It rescued a classic building that had been upstaged by new construction in recent years and made it the center of attention again.

In the process, it transformed the 34-story structure from a background building to the dominant and defining symbol on the skyline -- Baltimore's "Golden Oldie."

The rooftop restoration is the most visible part of a $1 million campaign by NationsBank to renovate the Light Street tower, Baltimore's only art deco skyscraper. The North Carolina-based banking giant gained control of it as part of its 1993 acquisition of Maryland National Bank.

The decision to remove the letters made good sense because the Maryland National name will soon be replaced by NationsBank, and the "mn" will lose its marketing value. But it also presented a dilemma for the bank and its architect, RTKL Associates, because the building is such a familiar landmark.

They could have played it safe and simply completed minimal repairs, patching holes left by the removal of the frame that held up the letters. But to its credit, NationsBank wanted to replace the letters with a look that was distinctive, marketable and respectful of the building it inherited.

The idea of reapplying gold leaf came from the bank lighting consultant, Douglas Leigh. Based in New York, he has made a career of illuminating landmarks such as the Empire State Building and the Chrysler Building. Now 87, he is old enough to remember how effective gold leaf was when it was first applied to skyscrapers in the 1920s and 1930s.

To apply the gold leaf, the bank employed a team of gilders headed by R. Wayne Reynolds of Baltimore and Michael Kramer of Olney. Mr. Reynolds has a studio in Hampden and is well-known locally, but he had never worked on such a large project. Mr. Kramer has extensive experience on projects such as this, including a spire on the NationsBank Plaza tower in Atlanta.

Before they could begin work in Baltimore, the artisans had to determine what areas to gild. From records, they knew this building was one of the few in Baltimore that ever had gold trim on the exterior. But when they examined the vestiges of the worn-off first coat, they discovered that it did not completely cover the roof's six pilasters and crown.

Instead, it was used sparingly to highlight ornamental shapes, including diamonds, scrolls, rosettes and abstract wheat sheaves. The gold was set against a black background, which in turn was set against the copper shingles. As a result, it was not nearly so striking.

"For the scale of this building, it was a pinstripe," Mr. Reynolds said. "This is not a pinstripe scale."

The gilders evaluated many options, from replicating the original design to covering the entire bonnet in gold. After careful study, the bank chose to strike a compromise and completely coat the ribs and crown.

According to Mr. Reynolds, bank officials were concerned that coating the entire roof in gold could be overkill, while repeating the original "pinstripe" pattern would not yield the dramatic results they were seeking.

"They could have made the wrong call, and it would have been a disaster," Mr. Reynolds said. "Baltimore would have resented it."

With the compromise, he said, the contrast between the weathered copper and the gold ribs was certain to be stunning. In all, they covered 6,400 square feet of roof surface, nearly the size of a baseball diamond. Although they have not disclosed exactly how much of the $300,000 budget went for the gold, one sign of its value is that it was kept in the bank's vault until it was needed.

A common misconception about the process of architectural gilding, which dates back to ancient Egypt, is that the gold leaf is painted on with a brush. It is not. Rather, the surface to be gilded is cleaned and coated with preparatives, and the gold leaf is applied by hand. In this case, the lead-coated copper ribs and cornice were covered with zinc chromate, a bright yellow liquid that inhibits rust, and then a slow-drying varnish. For NationsBank, the gold leaf was a 23-karat alloy with 96 percent gold, 3 percent silver, and 1 percent copper. It came in 3-inch squares backed by paper and in rolls of various widths.

Labor-intensive process

The artisans apply the gold leaf when the varnish is still sticky. The gold is so light that when it is held up to the varnish, it practically leaps off the paper backing and clings to the prepared surface, like a sock charged with static electricity. The trick for the artists is to cover each surface completely -- filling in even tiny cracks and crevices. It is a labor-intensive process, but it creates a strong seal. As the varnish cures over the next six months, it will bond with the gold to create an impermeable coat that won't rust or peel.

The durability of this coat is what makes the process cost-effective. While $300,000 may sound like a large sum, the gilders say it is cheaper than paint because it doesn't have to be done nearly as often.

"It will probably look that way for at least 25 years and maybe longer, depending on what happens to the environment," Mr. Reynolds said. "Fifty years is not uncommon." He and Mr. Kramer are so confident it will hold up that they guarantee it won't lose its shine for a decade, or they will re-clad it free of charge.

The second major change to roof appearance involves the sharper contrast between the copper shingles and the five-sided pilasters. When the building was first erected, the ribs with the gold leaf were set against the flatter copper shingles. At that time, however, the shingles were still copper-colored because they had not yet begun to oxidize. As a result, the top of the building was a mixture of copper and gold, a less pleasing combination than gold and green because neither metal stood out the way the gold does today.

NationsBank's careful planning extended to the way its crews patched the holes created when the steel frame that held up the "mn"signs were removed. To fill in the openings, roofer James Meyers painstakingly copied the shield-like forms of the pressed copper shingles already on the roof. Workers then coated the replacement shingles with chemicals designed to speed the oxidation process so they are close in color to the blue-green on the building already. Over time, the lines will blur even more.The golden touch

While the changes to the silhouette and surface color each were significant, the combination doubled the dramatic effect.

By removing the bulky "mn" letters, which were installed in 1971, the contractors revealed a profile that is considerably more slender than before, like a newly sharpened pencil. It's quite handsome -- the kind of steeply tapered silhouette that builders don't typically construct any more because the top floors are unprofitably small.

With the "mn," the tower was a respectable building but slightly tacky -- like a favorite uncle who has bad taste in neckties. Without the letters, it seems like a new building because its shape is so different from the ones all around.

"For all these years [the NationsBank building] has been dwarfed by boxy modern structures," Mr. Reynolds observed. "Now it's as if the tower is saying to its neighbors, 'Hey, you guys: Too bad you don't have any curves or tapers.' I think it brings the focus [of the skyline] back from the Inner Harbor to the historic &L; financial district."

The gold leaf accentuates the slimmer profile, which can be seen from all directions. What makes it particularly eye-catching is the way the sunlight and weather conditions affect its appearance. When the sun is high in the sky, it can be brilliant, almost blinding. But it stands out all the more at dawn and dusk, when the sun is lower in the sky and the light is especially flattering to the gold. Because of its height and tapered outline, the tower is the first building to catch the sun's rays in the morning and the last to lose its glow at night.

The crown glimmers impressively when the sky is clear blue, but the gold and green are even more striking against a stormy, purple sky.

Starting next month, NationsBank will begin illuminating the building at night. Its plan calls for three areas to be lighted: the bonnet, the terra-cotta and brick setbacks and the ground-level entrances. Judging from Mr. Leigh's past achievements, it ought to be spectacular.

Meanwhile, the attention to detail and quality of craftsmanship have set a high standard for any improvements to the rest of the building. Expectations will be high if and when the bank ever needs to replace the tower's windows, for example. It also will need to take good care of the art deco bronze work and other decorations inside. And it needs to find a way to tone down the candy-cane appearance of the red and white pole atop the mansard roof.

Even if it doesn't initiate any more exterior changes for a while, NationsBank has already has made a lasting contribution to the city's skyline. The lesson of this effort, however, is not so much about gold leaf as it is about golden opportunities.

Baltimore has a fine stock of older buildings, and many of them have changed hands in recent years. Even if only a small percentage of the new owners and tenants followed NationsBank's lead and restored some of the luster to these treasures, Baltimore would be a far more beautiful city. NationsBank has shown that historic preservation is not only good citizenship but good business as well.