Fat Over Lean
"Fat over lean" is a way of describing the proper way to order your layers of colors onto your painting. Your first layers should be "lean", meaning they have less oil. And your final layer should be "fat" which means they have more oil.
Think of it this way: Gamsol looks watery, it is lean and has no oil in it.
Paint in the tube is a mixture of pigment, calcium carbonate and oil. So it has some oil.
Then oils, like Galkyd, linseed oil, etc, are pure oil.
So when painting, you may use Gamsol and paint on earlier layers, and if you are going to add oil it should be done an later layers.
Think of it this way: Gamsol looks watery, it is lean and has no oil in it.
Paint in the tube is a mixture of pigment, calcium carbonate and oil. So it has some oil.
Then oils, like Galkyd, linseed oil, etc, are pure oil.
So when painting, you may use Gamsol and paint on earlier layers, and if you are going to add oil it should be done an later layers.
