1) Painting technique 
Craquelure (craquelé, crettatura) is the fine pattern of dense `cracking` formed on the surface of materials, either as part of the process of ageing or of their original formation or production. The term is most often used to refer to tempera or oil paintings, where it is a sign of age that is also sometimes induced in forgeries, and ceramics,.....
fine cracking that appears in old paintings
Network of fine cracks on a painting's surface that are due to age. In tempera paintings the cracks are barely visible, whereas in oil paintings they can be very distinctive. Craquelure is an...
Network of cracks. Caused by the shrinking of the paint or varnish. Craquelure Examples
a network of fine cracks or crackles on the surface of a painting, caused chiefly by shrinkage of paint film or varnish.