Uncovering What Was Always There

In 1980, restorer Gianluigi Colalucci climbed the scaffolding inside the Sistine Chapel and pressed a small solvent-soaked sponge against Michelangelo's ceiling. Beneath five centuries of candle soot, lamp smoke, and yellowed animal glue, a patch of startling sapphire blue emerged. No one alive had seen that color. Over the next fourteen years, Colalucci's team carefully stripped away layer after layer of accumulated grime.…