NEW ORLEANS — Smiling with satisfaction, Earl Barthe pushes back his wide-brimmed hat and runs his eyes over the intricate plaster trim of the Luling Mansion.

He’s sure his family helped form the room’s original decorations, elaborate patterns on the ceilings, and even likenesses of the first owner’s daughter, who died of yellow fever.

Today, Mr. Barthe is busy restoring the 165-year-old building. “You look at this kind of work and you’re looking at the pride people took in what they did,” Mr. Barthe, a fifth-generation master plasterer whose family’s work can be found in New Orleans’s historic homes and churches and even the Louisiana Superdome, said.

But in a city known for its arts traditions, Mr. Barthe is one of the few remaining craftsmen in what once was a flourishing trade.

His face lined from days in the sun, Mr. Barthe, who won’t say how old he is but acknowledges working the family business for 70 years, wears the white shirt and pants traditional to the trade. He insists his workers carry on the custom, too.

The Barthe family settled in New Orleans in the early 1800s. The business was established by his great-great-grandfather, a master plasterer from Nice, France, who married a woman from Haiti. The family was known in the term of the time as “free people of color.” These days Mr. Barthe refers to his family as Creoles, but most of all, he calls them plasterers.

“My father was a plasterer, his father was a plasterer, his uncles and everybody else were plasterers,” he said. “The Barthe children knew they had to be plasterers. Daddy didn’t want me to be a doctor, a lawyer, or an Indian chief.” In fine hotels, the old stores along Canal Street, the St. Charles Avenue mansions and the cemeteries’ tombs, you’ll likely see the work of Mr. Barthe and his family. “Every job is a hard job because of the time and care you have to take with it, the attention you have to pay,” Mr. Barthe said. “And it’s hard work climbing that scaffolding, hauling around the plaster. It’s the kind of work that makes you know you’ve done a full day when you stop.”

Mr. Barthe said about a dozen families were engaged in the business in its heyday.

“It was all men, and the one who had the most sons got the most respect,” Mr. Barthe said. “And those boys knew they better live up to what their fathers expected. If you did something wrong it reflected on the family. Nobody wanted that.”

To become a plasterer requires a three- to four-year apprenticeship, learning the tools, and how to mix plaster and prepare walls. The task can be daunting in old New Orleans homes; often walls reach up to 14-foot ceilings.

Patience and attention to detail are the keys to turning out the ornate medallions and trim a master plasterer can produce, or even a smooth wall of plaster. A worker will go over the surface repeatedly, blending the plaster, polishing, and blending until the surface is seamless. It’s not a job that young people now flock to. The last official apprenticeship class was in 1980, according to Earl’s daughter, Terry Barthe, who now runs the business.

“Americans don’t want to work hard,” Terry Barthe said. “We don’t want to sweat anymore. We don’t want to ‘earn’ a living, and that’s why it’s a dying art.”

Part of that is due to the use of drywall, which is cheaper than plaster and easier to learn to install.

“Don’t even say that word to me, it’s a dirty word,” Mr. Barthe said. “Just look at what happened with Hurricane Katrina. If you had sheet rock you had to rip it out and throw it away. If you had plaster you just washed down and were ready to go.”