The major restoration of the Sistine Chapel ceiling began in the 1980s. Preliminary experiments began in 1979, but the full restoration decision and work are generally dated to 1980.
The project was undertaken because centuries of candle smoke, soot, grime, wax, varnish, salts, and earlier repairs had darkened and obscured Michelangelo’s frescoes. Conservators first worked on the lunettes from June 1980 to October 1984, then moved onto the ceiling itself. The ceiling phase was completed in 1989, while work continued on the Last Judgment and other wall frescoes.
The restored colors were dramatically brighter than many viewers expected, prompting both admiration and controversy. Supporters argued that cleaning revealed Michelangelo’s original brilliance; critics questioned whether some later details or tonal effects had been removed. The restoration was unveiled by Pope John Paul II on 8 April 1994. Thus, 1979 refers to testing, while the 1980s correctly identify the start of the major restoration campaign.