About five dozen people lost jobs when Stitch Fix ceased operations at the factory and mill in November, Mr. Ford said. Some of them, he added, had been working at the sites for decades.

“All those skills would have been lost,” he said.

By March, the facilities had reopened as Buck Mason Knitting Mills, and several of the employees who had worked at them for Stitch Fix had been rehired.

The cloth mill in Shillington has started to produce fabrics for Buck Mason’s T-shirts and other tops using cotton grown in California, Georgia and Texas. Albert Bareika, who was hired by Buck Mason as the mill’s knitting lead in January, said there were plans to release a limited-edition T-shirt made with fabric produced at the facility on a 1940s-era Singer Supreme machine. Its Singer Supreme machine is one of a few still in operation, added Mr. Bareika, 66, who lives in nearby Leesport, Pa., and had previously worked for Stitch Fix at the mill.

At the Mohnton factory, some employees are responsible for cutting and sewing T-shirts, while others iron them by hand or package them for shipping. About 10,000 T-shirts are made there a month, Mr. Ford said. “By fall, we aim to double the capacity,” he added. “The goal is to quadruple it.”

The factory in Mohnton, a small borough in Berks County, Pa., produced hats and military uniforms before shifting to T-shirts, said Mr. Pleam, who lives in the borough. During the facilities’ heyday, in the late 1970s, the factory and mill employed about 100 workers, and the factory made about 22,000 T-shirts a week using fabrics from the mill, he said.