What is the “fat over lean” painting rule?
Fat over lean is better understood if considered as ‘flexible over less flexible’. When painting in layers, the proportion of medium used in each layer should be increased. The higher proportion of medium makes subsequent layers more flexible and prevents the painting from cracking. This rule has traditionally been kept by adding more and more oil to the solvent used. However, as Liquin is now more commonly used, it is the Liquin content which is increased. There is no need to use oil as well.
