craquelure

(French: “cracking”).  A pattern of fine cracks on the surface of a painting or a ceramic object. In an oil painting, craquelure forms because the paint dries and becomes less flexible as it ages and shrinks. It can be used by experts to determine the age of a painting and to detect forgeries.

Screen Shot 2017-07-18 at 5.21.15 PMJan and Hubert van Eyck. The Ghent Altarpiece. Detail of craquelure in the Virgin Mary panel. Oil on panel. Completed ca. 1432. Cathedral of St. Bavo, Ghent, Belgium.