“After you put the steak in contact with it, there’s a lot of spare heat left to cook with,” he said. “Cast iron doesn’t drop in temperature as much as thinner pans with better conductivity,” like aluminum and stainless steel.

Thick-bottomed cast-iron pans evolved for use in charcoal embers and on wood stoves, when maximizing limited heat was the priority. In Appalachia, cast iron survived when many modern cooks switched to lighter pans, which heat up quickly on gas and electric stoves, Ms. Lundy said.

“That skillet became part of the imagery of the Appalachian woman,” said Ms. Lundy, who identifies herself as a member of the “hillbilly diaspora” and has just published a cookbook called “Victuals.” She grew up in Louisville, Ky., and lives in North Carolina. Her family lived for at least four generations in Corbin, Ky., making everything from pork chops to cornbread, cobblers and even biscuits in cast iron. “The first thing any mountain cook will tell you is the history of her skillets,” she said.

Soon, the same may be true of all cooks. Mr. Whitehead said a customer had recently come in to buy a Finex skillet after his first son was born. “The dad wants to start using it now,” he said, “so it will be ready for the boy when he turns 18.”

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