Fat over lean or fat over thin
The recommended means of layering oil color: the first layer of oil colors should be leanest (least oil, or more thinner with less oil) followed by layers with progressively more fat (more oil.) Following this principle results in a work less likely to crack after aging. Conversely, in order to encourage cracking, the painter should do the reverse.Other sites concerned with fat over lean: "Chalkboard" on color theory, painting materials and techniques. Here is information on stretching canvas and preparing grounds, along with brushes, palette knives, palettes, drawing, colors, types of paint and how to control them. Chalkboard comes from Ralph Larmann at the University of Evansville, IN. Also see crackle, overpainting, surface, and underpainting.