Sistine Chapel ceiling of the Sistine Chapel. At the outset, the plaster, "intonaco", began to grow mold because it was too wet. Michelangelo had to remove it and start again. He then tried a new formula created by one of his assistants, Jacopo l'Indaco, which resisted mold and entered the Italian building tradition. Because he was painting "fresco", the plaster was laid in a new section every day, called a "giornata". At the beginning of each session, the edges would be scraped away and a new area laid down. The edges between "giornate" remain slightly visible; thus, they give a good idea of
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