Sinopias are the preparatory drawings that are used in the fresco technique. The technique calls for the painting's color pigments to be applied to the wall when the top layer of the plaster is still wet. The artist was therefore forced to divide the wall into sections called "giornate", or days, each of which corresponded to the part of the fresco that had to be completed precisely in a day. With this system painters could quickly decorate large wall surfaces with lasting results, although the little time available to the artist made it almost impossible to correct any mistakes. For this reason, the preparatory drawing was essential for testing the composition, studying the poses of the figures, and defining the various details. The sinopias were used to do this: the name comes from the city of Sinop on the Black Sea, where the red dust that was used to make the drawing came from.
