Vatican officials unveiled paintings on the ceiling. These were identified as the first known icons of the apostles: Peter and Paul. Discovered along with the earliest known images of the apostles John and Andrew in an underground burial chamber beneath an office building on a busy street in working-class Rome neighbourhood.
The images are discovered by the new laser technique allowing restorers to burn off centuries of thick white calcium carbonate deposits without damaging the brilliant dark colors of the paintings underneath. This technique could revolutionalize the way restoration work is carried out in the miles of catacombs that burrow under the Eternal City where early Christians were buried.
The icons were discovered on the ceiling of a tomb of an aristocratic Roman woman at the Santa Tecla catacomb, near where the remains of the apostle Paul are said to be buried.
In this case, the small burial chamber at the end of the catacomb was encased in up to two inches (five centimeters) of calcium carbonate. Restoration using previous techniques would have meant scraping away the buildup by hand, leaving a filmy layer on top so as not to damage the painting underneath.
Using the laser technique, restorers were able to sear off all the deposits by setting the laser to burn only on the white of the calcium carbonate; the laser’s heat stopped when it reached a different color. Researchers then easily chipped off the seared material, revealing the brilliant ochre, black, green and yellow underneath, Mazzei said.
Similar technology has been used on statues, particularly metallic ones damaged by years of outdoor pollution, she said. However, the Santa Tecla restoration marked the first time lasers had been adapted for use in the dank interiors of catacombs.