Betty Lynn Seifert was not cowed by the prospect of cleaning up a heavily encrusted, 200-year-old pistol loaded, perhaps, with highly unstable gunpowder.
"I've drilled grenades," said Seifert, chief conservator for the Maryland Historical Trust. "It doesn't bother me."
While working for the Maine State Museum in the 1970s, Seifert drilled orange-sized, cast-iron grenades recovered from the remains of the Defense, a ship scuttled by American sailors in the Penobscot River during a 1779 confrontation with the British. The drilling was needed to remove the powder and render the artifacts safe.
She survived the work, "although I can tell you that when they hissed, it was a little nerve-wracking." She did the job with the weapons under water, slowly, using an old-fashioned brace-and-bit instead of power tools.
Since last spring -- after other conservators waved off the job -- Seifert has been working to clean and preserve a flintlock pistol, unearthed by utility workers in January during the construction of Oriole Park at Camden Yards.
Just how the nearly intact old gun got buried in the Camden Yards area can't be known with any certainty, because it was found in a utility trench, and not in a systematic archaeological excavation.
But project archaeologist Christopher Goodwin and his historian, Martha R. Williams, say it may have been left behind by French troops under the Comte (Count) de Rochambeau. They camped at the site in what was then woods and fields on their way north from Yorktown in 1782.
Explosions are no idle worry, Seifert said.
The powder in antique guns and cannonballs can become chemically unstable after years under ground. Moving it from the airless mud into oxygen-rich air can be enough to touch off an explosion.
Even solid iron cannonballs, with no explosives, have heated up enough from rapid oxidation to blow apart after recovery, she said.
"I'm not cavalier" about the potential hazards, Seifert said, nodding toward the gun. "You'll notice it's in water, and I try to point it away from myself."
It was not entirely clear, however, whether the Camden Yards pistol was loaded.
"In the X-rays," Seifert said, "it was hard to tell if there was a . . . ball in there, or just a concretion [a clump of rust and dirt]."
Seven months or work with the gun, however, have eased any concern she may have had.
Seifert got her first look at the old pistol last winter at Goodwin's offices in Frederick.
The wet, dark, oxygen-poor environment under ground had protected the gun's brass and iron from the worst ravages of corrosion. The lack of oxygen also saved the wooden stock -- maybe walnut -- from the bacteria and fungus that otherwise would have rotted it long ago.
Only the ramrod, flint and a screw were missing. Other threaded screws and a delicate spring are clearly visible on X-rays.
"It really is amazing," Seifert said.
But the weapon was caked, especially the metal parts, with a hard, grainy aggregate composed of metal salts, dirt and minerals, the work of limited and very slow corrosion.
The aggregate also makes the wood brittle, Seifert said.
But worst of all, the wood was cracking. Although Goodwin's crew had placed the gun in a double plastic bag, it had been out of the ground too long and was drying out.
"They got worried," she said. She told them to add water to the bag and place it all in a refrigerator.
In March, Seifert went to work on the pistol, first at the Jefferson Patterson Park and Museum in St. Leonard, and later in her agency's laboratory in Crownsville.
Her first job was to halt the damage being caused by the gun's return to the surface. "Chemistry is working against you," she said.
The oxygen-rich air was accelerating corrosion, while daily changes in temperature and humidity were speeding destruction the wood. Light catalyzes both processes.
After photographing the gun to record her work, Seifert slipped it into a water bath of sodium carbonate, both to re-wet the wood, and to stop the corrosion.
In corrosion, the metal molecules combine slowly with oxygen to form a compound -- ferrous oxide, or rust, in the case of iron. In the bath, "the carbonate acts like a buffer, and scavenges oxygen so you don't get active corrosion," she said.
After about two weeks, Seifert added electricity to the brew -- electrolysis. By sending a single amp of power into the tank, she supplied electrons to replace those stripped from the metal during corrosion.
In response, after several months, the gritty aggregate has fallen away.
Of the iron, she said, "we'll never get back to anything resembling the original surface," Seifert said. The barrel, for example, is visibly smaller in diameter that it was originally because of the iron lost to corrosion.
Nevertheless, what remains is "a nice surface, and evidence of what the original surface was."