BORDENTOWN, N.J. — The machines at Independent Record Pressing whirred and hissed as they stamped out a test record. The business’s owners waited anxiously for Dave Miller, the plant manager, to inspect the still-warm slab of vinyl.

“That’s flat, baby!” Mr. Miller said as he held the record, to roars of approval and relief. “That’s the way they should come off, just like that.”

Independent Record Pressing is an attempt to solve one of the riddles of today’s music industry: how to capitalize on the popularity of vinyl records when the machines that make them are decades old, and often require delicate and expensive maintenance. The six presses at this new 20,000-square-foot plant, for example, date to the 1970s.

Vinyl, which faded with the arrival of compact discs in the 1980s, is having an unexpected renaissance. Last year more than 13 million LPs were sold in the United States, according to the Recording Industry Association of America, the highest count in 25 years, making it one of the record business’s few growth areas.