Patches of calcium lactate have dulled the colors of the famous 16th-century mural, which hasn’t been cleaned since 1994. Experts will carefully restore the artwork to its former glory

The Last Judgment is located behind the Sistine Chapel's altar. Ann Ronan Picture Library / Photo12 / Universal Images Group via Getty Images

In the five centuries since Michelangelo painted the Sistine Chapel , millions of visitors have marveled at his work. Unfortunately, their sweat also coated the walls in microparticles, damaging the murals over time. Now, experts are cleaning and restoring the Last Judgment , the mural behind the chapel’s altar, for the first time in three decades.

“People are going to be able to see Michelangelo’s magical, marvelous colors again,” Barbara Jatta, the head of the Vatican Museums, tells the London Times ’ Tom Kington.

The Italian Renaissance artist completed the mural in 1541, nearly 30 years after he painted the chapel’s ceiling, which features scenes from the Old Testament.…