Inside an unassuming cement block building off Hempfield Hill Road in Silver Spring, a worker guides a crucible of sun-yellow molten metal to one of a dozen flat molds formed of hardened sand laying on the ground.

Smoke rises and molten metal flows as he pours the 2,400-degree liquid into the molds.

After it cools, workers will remove a 2-foot-wide plaque commemorating the Lake of the Forest historic district in Bonner Springs, Kan. (The lake was created for ice harvesting for railroads in 1888 and is part of a historic housing district listed on the National Register of Historic Places.)

Other plaques poured on this recent Wednesday commemorate the Alamo Placita neighborhood of Denver, Colo., and the Astor Historic District in Green Bay, Wis.

From the casting floor at Paul W. Zimmerman Foundries Co., they'll move to a room where workers will use sanding wheels and grinders to smooth rough edges. Their backgrounds will be painted and a chemical patina and protective lacquer applied before being shipped to customers.

"This is how bronze casting has been done for a long time," said Andrea Zimmerman, the foundry's operations manager.

Indeed, mankind has been combining copper, tin and nickel and lead — bronze's ingredients — to serve its needs for millennia.

And Paul W. Zimmerman Foundries has been casting items in bronze, mainly, although it also works in aluminum, for 75 years.

The family-owned foundry focuses on plaques, but it wasn't always so.

The foundry was started by Zimmerman's husband's grandfather, Paul W. Zimmerman, in 1937.

About a dozen people work for the foundry, most of whom are related. That includes Andrea Zimmerman's teenage son, who works part time doing odd jobs.

"They did a lot of ship parts for the Navy for World War II. Gun mounts … lots of intricate little parts. The Navy is our oldest customer," she said.

But by the 1970s, parts work began moving overseas.

"They were really hurting in the '80s," Zimmerman said. The company decided to focus on making plaques.

Its work came to the attention of the Erie Landmark Co., then located in Chantilly, Va. Erie Landmark bought and resold Zimmerman plaques.

In 1993, Zimmerman bought Erie Landmark after Erie's owner wanted to move back to Israel, Zimmerman said.

The Erie Landmark name was better-known than the foundry's name, so the foundry markets its plaques under that name, Zimmerman said.

"If you go to New Mexico, or Texas or California and say, 'I have a plaque from Erie Landmark,' everyone goes, 'Oh, I do, too.' But if you say, 'It was really made by Paul Zimmerman Foundries,' they go, 'Huh?'\!p" she said.

For a time, the plaque business boomed.

"At our peak, we were doing $1.5 (million) to $2 million a year. But with the economy … If people aren't ordering and buying personal items because the economy's bad, their last thought is going to be, 'Oh, I need a plaque,'" Zimmerman said.

At bottom, Zimmerman said, business was half its peak.

So two years ago she turned to Mantech, a York-based nonprofit industrial resource center.

Zimmerman, 46, began working at the foundry after she was downsized from her executive assistant position at Bon-Ton six years ago.

At Bon-Ton she had picked up advertising and marketing skills, but she admits she knew nothing about the foundry end of things. Mantech helped her figure that out, she said.

For instance, Mantech helped determine appropriate pricing, which Zimmerman said no one at the foundry knew how to do.

Grave markers account for about 30 to 40 percent of business and plaques for buildings and historical districts account for another 30 to 40 percent.

Military work accounts for 15 to 20 percent.

"My father-in-law" — foundry president Paul Zimmerman Jr. — "is an ex-Marine. He's very sensitive to VWFs, American Legions, schools, hospitals … so when they come order a plaque, they never pay retail. They always pay wholesale," she said.

Business has begun to rebound over the past year, she said.

"I think I'm actually a pretty good fit for (the job) because I don't think in terms of foundry, I think in terms of business," she said. "... I'm in charge of finding more business and keeping us going."

One of her ideas, which she said was initially met with a cool reception, was to offer January incentives.

"We slow down after Christmas until maybe after March because, especially in the northeast, people are dealing with snow and the cold weather, so they don't think of putting a plaque out — until April, (when) they go, 'Oh my God, Memorial Day is only so many days away. I have to order my plaque,' and things start picking up," she said.

The company aims for a four- to six- week turnaround, but Zimmerman said many orders are filled sooner.

"We can do just about anything in bronze that you could think of. As long as you can draw it with a pencil, you can turn it into a plaque," she said.

Recently, the foundry created a 14-foot-diameter bronze plaque for Penn State University.

Locally, its work can be seen at Soldiers and Sailors Monument in Penn Square, where plaques honor World War II and Korean War veterans.

"Lititz is a gold-mine for our plaques," Zimmerman said. "I would say 98 percent of everything that is in Lititz Springs Park, we've done for them," she said.

Zimmerman plaques also are at Franklin and Marshall College, the 208-year-old William Montgomery house next to the Lancaster County Convention Center and at Veterans Plaza at Queen and Chestnut streets in Lancaster city.

That's perhaps Zimmerman's most recent local plaque. It was created to honor the Merchant Marine during World War II and was dedicated on Veterans Day.

"It's kind of fun, when you go to other towns or other places … and you see a plaque and you look at it and you're like, 'Is that ours?'"

Plaques don't bear the foundry's name, but Zimmerman said she can recognize them by their background pattern and paint color.

dnephin@lnpnews.com