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 three to get the width and by two to get the height. Maintaining the ratio, there were six windows down each side and two at either end. Defined proportions were a feature of Renaissance architecture and reflected the growing interest in the Classical heritage of Rome. The ceiling of the chapel is a flattened barrel vault springing from a course that encircles the walls at the level of the springing of the window arches. This barrel vault is cut transversely by smaller vaults over each window, which divide the barrel vault at its lowest level into a series of large