Sistine Chapel ceiling how the work progressed. It was customary for fresco painters to use a full-sized detailed drawing, a "cartoon", to transfer a design onto a plaster surface—many frescoes show little holes made with a stiletto, outlining the figures. Here Michelangelo broke with convention; once confident the "intonaco" had been well applied, he drew directly onto the ceiling. His energetic sweeping outlines can be seen scraped into some of the surfaces, while on others a grid is evident, indicating that he enlarged directly onto the ceiling from a small drawing. Michelangelo painted onto the damp plaster using a wash technique to apply
Sistine Chapel congregations. These included the Christmas Day and Easter masses, at which the Pope himself was the celebrant. The other 27 masses could be held in a smaller, less public space, for which the "Cappella Maggiore" was used before it was rebuilt on the same site as the Sistine Chapel. The "Cappella Maggiore" derived its name, the Greater Chapel, from the fact that there was another chapel also in use by the Pope and his retinue for daily worship. At the time of Pope Sixtus IV, this was the Chapel of Pope Nicholas V, which had been decorated by Fra Angelico.