For most of the twentieth century, every photograph of Michelangelo's ceiling showed the same muddy brown palette, and generations of viewers assumed that was simply how Michelangelo had painted it, a deliberately sombre counterpoint to the chapel's solemn function. In 1979 the conservator Gianluigi Colalucci noticed a crack in one lunette and found bright, clear colour underneath, unmuddied fifteenth century pigment sitting beneath centuries of soot, candle smoke and earlier restorers' own darkened varnish.
The Vatican Museums committed to a full cleaning, carried out from 1980 to 1994 using solvent compresses applied panel by panel. As the grime came away, figures long assumed to be earth toned emerged in colours nobody alive had seen: the twisted, muscular Libyan Sibyl turned out to be painted in lime green and coral pink, her flesh a pink salmon tone, her book the colour of fresh cream.
The transformation was dramatic enough to provoke real scholarly alarm rather than simple celebration. Art historian James Beck called the project an artistic Chernobyl, arguing that Michelangelo had likely added shadow and modelling in dry secco paint after the fresco itself had set, and that the cleaning had stripped away the artist's own final adjustments along with the dirt. Prominent contemporary artists, including Andy Warhol and Robert Rauschenberg, petitioned Pope John Paul II to pause the work. Colalucci and the Vatican's own restoration team held their ground, insisting the underlying pigment analysis showed true buon fresco throughout and that what critics mourned as Michelangelo's lost intention was in fact five centuries of soot finally coming off.