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
Restoration of the Sistine Chapel frescoes watercolour, to integrate the pictorial material. These areas are distinctively textured with vertical brushstrokes, not visible from a distance but easily discernible as restoration work when viewed close up. Certain small areas were left unrestored, in order to maintain a physical record of the previous restorations that had taken place, for example, an area left with overpainting and candle wax, and another area demonstrating the attempt to counteract salination with oil. Once the many layers of candle wax, varnish, and animal glue were removed from the surface of the Sistine Chapel frescoes, they became subject to dangers that could not