Restoration of the Sistine Chapel frescoes smoke and exhaust fumes of the city, being "much dirtier than the ceiling proper". The building was a little unstable and had already shifted considerably prior to Michelangelo's work of 1508, causing cracking of the ceiling, the crack in the "Judith" pendentive being so large that it had to be filled with bricks and mortar before painting. The upper part of the ceiling provided Michelangelo an irregular surface due to cracks and water seepage. Continued ingress of water from the roof and from unroofed exterior walkways above the ceiling level had caused seepage which carried down salts from the building
Sistine Chapel Choir Thus the ""magister capellae"" came immediately after the cardinals, followed, in the order given, by the ""sacrista"", ""cantores"", ""capellani"" and ""clerici"". With the building by Sixtus IV (1471–84) of the church for the celebration of all papal functions since known as the Sistine Chapel, the original ""schola cantorum"" and subsequent ""capella pontificia"" or ""capella papale"" became the ""capella sistina"", or Sistine Choir. Up to this time the number of singers had varied considerably, there being sometimes as few as nine men and six boys. By a Bull dated November, 1483, Sixtus IV fixed the number at twenty-four, six for each