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ROME — For nearly 600 years, Lorenzo Ghiberti’s panels depicting scenes from the life of Christ on the north doors of the Baptistery in Florence were exposed to the elements and other vicissitudes of time.

Now, the gilded bronze doors with their 28 panels have been replaced with replicas made by a team of artisans using the materials and techniques mastered centuries ago by the Renaissance sculptor and his workshop.

The replicas of the doors, which together weigh nearly 20,000 pounds, were installed last week and will be officially unveiled at the Baptistery on Saturday.

The new doors are “all handmade, all hand-chiseled, all hand-worked. It took 350 hours for each panel,” said Enrico Marinelli, the president of the Guild of the Dome, a group of private sponsors who paid for the replicas at a cost of 150,000 euros, or about $162,500, per panel. The doors were cast in the foundry of the Frilli Gallery, which Mr. Marinelli owns.

He said the workers experienced the same challenges as Ghiberti had in working with bronze.

“The only advantage we had was electricity,” Mr. Marinelli said, “so we could turn on the oven and know with certainty that the bronze would melt.”

As molds for Ghiberti’s original panels were not available, models were made using the lost-wax casting technique and 3D technology. A video on the guild’s website shows the processes.

At the same time that the team was making the replicas, experts from the Opificio delle Pietre Dure in Florence, the city’s research and restoration institute, were restoring Ghiberti’s original doors, which he fashioned from 1402 to 1424. They are now on permanent exhibit in the museum of the Opera del Duomo.

The restoration revealed detailing that had long been lost under layers of soot, like a frieze of plants and animals, as well as minute features of the biblical figures. Sections of the original gilding also re-emerged.

Ghiberti’s second set of portals for the Baptistery, the so-called Doors of Paradise, made between 1425 and 1452, were put in the museum several years ago after a lengthy restoration.

Mr. Marinelli’s father made replicas of the Doors of Paradise, which are now mounted on the Baptistery, in the Frilli Gallery foundry 25 years ago.