<P> Contrary to popular belief, he painted in a standing position, not lying on his back . According to Vasari, "The work was carried out in extremely uncomfortable conditions, from his having to work with his head tilted upwards". Michelangelo described his physical discomfort in a humorous sonnet accompanied by a little sketch . </P> <P> The painting technique employed was fresco, in which the paint is applied to damp plaster . Michelangelo had been an apprentice in the workshop of Domenico Ghirlandaio, one of the most competent and prolific of Florentine fresco painters, at the time that the latter was employed on a fresco cycle at Santa Maria Novella and whose work was represented on the walls 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 . </P> <P> 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 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 . </P> <P> Michelangelo painted onto the damp plaster using a wash technique to apply broad areas of colour, then as the surface became drier, he revisited these areas with a more linear approach, adding shade and detail with a variety of brushes . For some textured surfaces, such as facial hair and woodgrain, he used a broad brush with bristles as sparse as a comb . He employed all the finest workshop methods and best innovations, combining them with a diversity of brushwork and breadth of skill far exceeding that of the meticulous Ghirlandaio . </P>

The medium of the artwork that decorates the sistine chapel ceiling is