– J. Del Conner’s biggest headache is currently out of stock, but he fears more could be en route, via cargo ships from China.

Conner, 69, designs and sells cast-iron firebacks, large plates that are propped up inside fireplaces to protect the bricks and radiate heat. Conner started Pennsylvania Firebacks in 1979 in Philadelphia and at his peak was selling 1,000 a year at $300 to $900 apiece, depending on size and intricacy of design.

That number is down to about 600, and he blames China. Conner says foundries there have stolen his fireback designs, made cheaper versions, and shipped them to suppliers in the United States. Conner was so frustrated, he bought one of the knockoffs himself.

The copies are often hundreds of dollars cheaper than his product, but the quality, he argues, is far from the same.

“This is the one I made, and that’s the copy from China,” he said, holding two firebacks. “It’s the same exact thing. Theirs is 39 pounds and mine is 56. The back of theirs is hollow. Mine has my signature on it.”

One of J. Del Conner’s firebacks is used in his home, which doubles as a studio, in Hamburg. Firebacks are used to protect the bricks in a fireplace and they help to push heat back into the house.

Conner said he’s tried to track down the manufacturer, which has been fruitless. Hiring a lawyer, he said, wouldn’t be cost-effective.

Instead, he’s focused on trying to reach out to the suppliers in the U.S. He’s found his designs for sale on Home Depot’s website.

“There’s not much you can do. You can send letters,” he said.

Many websites now say “no stock currently available” for the knockoffs, “but that doesn’t mean a shipment isn’t on its way now from China,” Conner said.

Jesus Espinoza, a spokesman for the Alliance for American Manufacturing, said trademark infringement affects every industry, from telecommunications to fashion, even something as unique as firebacks.

“It’s basically theft,” Espinoza said. “Family-owned business are especially affected.”

Country Iron Foundry, a Paoli-based fireback manufacturer, did not return requests for comment. Firebacks are also made in England, Belgium and France, Conner said.

While firebacks are the bulk of Conner’s income, he’s also an inventor of sorts, making bird’s-eye-view maps, illustrations and wax molds. Until Philadelphia’s soda tax arrived, Conner made his own brand of black cherry soda for a decade, based on a recipe by the physician Philip Syng Physick, his great-great-grandfather. The soda was sold in Old City, he said, and he even held a “Phyzz Phest” every year at the Physick House on S. Fourth Street.

“The soda tax, in seven months, killed it,” he said. “It just got to be too much.”

Conner sketches and designs the firebacks in a home office, taking rubber molds to a nearby foundry. His home is filled with guitars and artifacts. One of his favorite fireback designs, the “North Star,” shone behind the fake logs in his gas fireplace.

Conner said a chimney sweep friend had recommended making firebacks, and Conner was familiar with them, having seen a roomful on display in the Mercer Museum in Doylestown.

He was licensed to make reproductions from Winterthur Museum. Some of Conner’s pieces have been displayed at the Museum of the American Revolution. He’s now designing firebacks for the daughter of the late British children’s author Roald Dahl.

But Conner says he can’t compete with China and fears there could be more firebacks coming.

“One of my designs, the ‘Field of Leaves,’ was selling for less than what it cost me to make it here in Pennsylvania,” he said. “How can you compete with yourself? I’d be losing money on every one.”