Restoration of the Sistine Chapel frescoes smoke and exhaust fumes of the city, being "much dirtier than the ceiling proper". The building was a little unstable and had already shifted considerably prior to Michelangelo's work of 1508, causing cracking of the ceiling, the crack in the "Judith" pendentive being so large that it had to be filled with bricks and mortar before painting. The upper part of the ceiling provided Michelangelo an irregular surface due to cracks and water seepage. Continued ingress of water from the roof and from unroofed exterior walkways above the ceiling level had caused seepage which carried down salts from the building
Illusionistic ceiling painting From 1691 to 1694 Andrea Pozzo painted the "Entrance of Saint Ignatius into Paradise" on the nave vault of Sant'Ignazio, Rome, with theatricality and emotion. Illusionistic ceiling painting Illusionistic ceiling painting, which includes the techniques of perspective di sotto in sù and quadratura, is the tradition in Renaissance, Baroque and Rococo art in which trompe l'oeil, perspective tools such as foreshortening, and other spatial effects are used to create the illusion of three-dimensional space on an otherwise two-dimensional or mostly flat ceiling surface above the viewer. It is frequently used to create the illusion an open sky, such as with