What Does Fat Over Lean Really Mean?
Fat over lean, Fat over lean, Fat over lean - you hear this all the time in art classes for oil painters. But what does it mean?
It’s a good rule of thumb because it both helps you build a structurally stronger oil painting, and it makes it easier to paint wet into wet.
It’s a clever saying, because it has two meanings.
First meaning is the simplest: Paint your first layers physically thinner than the last layers. Start with thinner lines and stumbled paint. Save your impastos (thickest brush strokes) for last. This makes your paint strokes look better because you’re not breaking your beautiful thick strokes apart with more paint strokes as much.
It’s also much easier to paint wet into wet doing this. Try this out: Paint some thin brush strokes on a canvas or other substrate. Then take a thick frosting like patch of paint and you can put it right on top the first layer even before it dries. It lays down easily. Now try the opposite. Put a nice thick stroke of paint on a canvas. Now thin some paint with a bit of oil or spirits, then take that thin paint and try to paint over the first thick stroke. You can’t do it! The thin paint will pick up the wet thick stroke. Once you see it for yourself, you’ll really understand this aspect of the saying: Fat over lean.
Second meaning has to do with the actual FAT or linseed OIL in your paint. Using extra linseed or walnut oil as a medium works better for top layers of a painting. For your early layers you could use more turpentine or mineral spirits instead. This builds a structurally stronger painting, where the top layers bond more effectively to the lower first layers. You want to build good bonds so your painting will last for generations!
Related to this concept is the practice of using earth pigments (which absorb more oil than most pigments) in the underlayers of paintings. Earth pigments are really practical for SO many reasons, but using them for underpainting, for toning a canvas or sketching is very smart. My favorite earth pigment for underpainting and toning is raw umber. I like the neutral warm brown. Because it absorbs so much oil it dries more quickly than other colors, another reason it’s a good choice for underpainting.
I hope this helps!
All this stuff really matters to me because I want my paintings to last. I want them to become part of a family’s treasured keepsakes, part of a region’s historical record, something beautiful from another time. Not all artists care about this - and they don’t have to - but I am VERY interested in creating art that is going to last.
photo by Dennis Brown