CHIAROSCURO : Literally means “bright-dark” in Italian and describes the technique, in painting or drawing, of modeling three-dimensional figures by contrasting or gradating areas of light and dark. Leonardo da Vinci was among the first to use chiaroscuro to break out of the tradition of flat, one dimensional outlining of figures. One of the great achievements of the Renaissance, chiaroscuro soon became part and parcel of painting. Rembrandt is the acknowledged master of the technique; if you want a more recherché example, try Caravaggio.
PENTIMENTO: A painter’s term derived from the Italian word for “repentance,” and referring to the evidence that an artist changed his mind, or made a mistake, and tried to conceal it by painting over it. As time goes by, the top layer of paint may become transparent, and the artist’s original statement begins to show through. Pentimento can often be found in seventeenth-century Dutch paintings, in which the artists commonly used thin layers of paint to obliterate an element of a composition— one of the children, say, in an interior— only to have its ghost reappear behind a lady’s dress or a piece of furniture a couple hundred years later. One of the most famous examples of pentimento is the double hat brim in Rembrandt’s portrait Flora as seen above.