PARIS — Painting conservation is perilous business, requiring the perfect blend of historical knowledge, technical skill, and respect for the immeasurably fragile, ancient object held gently between gloved hands. Just ask Cecilia Giménez, the 83-year-old amateur painter whose farcically botched attempt to restore an almost century-old fresco of Christ in her local church in Borja, Spain, propelled her to international infamy. Other conservation mishaps have been far less amusing.

In 2011, the Louvre’s director of conservation, Ségolène Bergeon Langle, resigned in the midst of a scandal that followed the restoration of Leonardo da Vinci’s “The Virgin and Child with Saint Anne” (c. 1503). Begun in 2009, the restoration was supposed to be a celebratory event to kick off a series of restorations of Leonardo paintings in the Louvre’s collection (of 15 known to exist, the museum owns six). However, Langle, along with other experts, felt the conservators had gone too far in removing the various layers of yellowed varnish, eliminating or modifying original aspects of the painting.

“They almost completely removed the varnish,” Jean-Pierre Cuzin, former director of the Department of Painting, who also resigned in protest of the restoration, told Le Monde in 2012. “Now ‘Saint Anne’ looks like a bright pink-and-blue painting next to the very somber palette of the others — ‘The Mona Lisa,’ ‘Saint John the Baptist,’ ‘The Virgin of the Rocks.’ It disrupts the harmony of the group.”

Although the restoration of “La Belle Ferronnière,” the second painting in the series, was completed without incident, the restoration project continues to draw frequent and virulent criticism. Carlo Pedretti, professor emeritus of art history and chair of Leonardo Studies at the University of California, Los Angeles, referred to the Louvre’s restoration campaign as “a contagious mania […] done to create publicity.”

Of the most recent restoration endeavor, Micheal Daley, director of the restoration watchdog website Art Watch UK, told Hyperallergic: “I cannot believe that nothing but varnish has been removed: Varnish could never have posthumously completed Leonardo’s own technique on his behalf.” Nevertheless, the Louvre moved forward with the project, and on November 9, “Saint John the Baptist” (c. 1513–16), the third Leonardo painting to undergo restoration, was put back on display in the Grande Galerie.

Commissioned around 1508, “Saint John the Baptist” is one of three Leonardo paintings considered masterpieces among the six in the Louvre’s collection, along with “La Gioconda” (c. 1503–06) and “The Virgin and Child with Saint Anne.” In 2009, it was decided that “Saint John the Baptist,” whose last restoration had been in 1802, needed sprucing up. “The painting had turned orange,” Sébastien Allard, director of the Louvre’s Department of Paintings, told Le Monde. “The cross, the animal skin, and the details of the hair were no longer visible.”

An initial radiological diagnostic carried out by the French Museum Center of Research and Restoration (C2RMF), whose laboratories are located in the basement of the Louvre, attributed the discoloration to 17 layers of extremely oxidized varnish, 110 microns thick, that were discovered on the painting’s surface. In October 2015, the C2RMF conservation team set about a painstaking restoration process aimed at improving the work’s “legibility.”

A year later, although the painting remains somber, the dull ochre of Saint John’s skin has given way to a soft golden glow. “The last layer of varnish was left untouched,” Regina Moreira, head of the restoration team, told Le Monde. “After a while the painting stopped getting clearer, and the risks of removing the final layers began to outweigh the rewards.”

Apart from returning “Saint John the Baptist” to a former glory, the C2RMF team also sought to learn more about the Renaissance master’s creative process. X-rays revealed that Leonardo repeatedly retouched the painting until the end of his life in 1519, notably changing several times the position of Saint John’s arm.

For museum curator Vincent Delieuvin, an Italian Renaissance specialist, this constant tinkering is evidence of Leonardo’s tireless quest for perfection. “There is great hesitation on the part of Leonardo as to how to capture movement,” he told Le Monde. “Each position of the body, of the hand, of the arm, underwent subtle changes. The manner in which he imbues life into the material is very impressive.”

The painting was commissioned as a personal object intended for private devotion, and there is something deeply intimate in the androgynous figure’s soft gaze. Stare patiently at it for a moment, allowing your eyes to adjust to the tenebrous palette, the extreme chiaroscuro, and the cross and animal pelt emerge from the darkness. You will come to appreciate the éclats of blond in his Venetian curls, the seemingly impossible sharpness and clarity of the finger, raised in a sweeping gesture up toward the heavens. Beckoning us forward, a playful smile curling over his face, Saint John momentarily mutes the symphony of kitsch raging through the Louvre on a Thursday afternoon. The amorphous mass of monochrome synthetics, the silver glint of dueling selfie sticks, the collision of impregnated reverse-backpack wearers all fade away, leaving the viewer free to commune silently with a divine presence.