What does the term "fat over lean" refer to in painting techniques?

The term "fat over lean" in painting techniques refers to the practice of using thicker mediums or more oil-rich paint layers on top of thinner, less oily or water-based layers. This principle is important for several reasons.

Firstly, it helps to prevent cracking and other ailments in the paint layer as it dries. Thicker layers contain more oil, making them more flexible and able to accommodate the drying process of the layers beneath them, which tend to dry more rigidly. When a more flexible layer is placed over a more brittle one, it ensures that the upper layer can shrink or expand without causing damage to the underlying layer.

Additionally, following the "fat over lean" rule supports the overall integrity and longevity of the artwork. By adhering to this technique, artists can enhance the depth and richness of their paintings, as the use of thicker paint can create more texture and allow for more dynamic visual effects.

This understanding of the correct layering technique in painting ensures that artists maintain the aesthetic and structural quality of their works, thereby following established artistic standards.