Too Stiff or Too Short? Why Painters Use Oil Painting Medium—and What It Leaves Behind

Many painters add oil painting medium because the paint does not behave the way they want. It may feel too stiff or too short. They may want more flow, greater transparency, a longer stroke, different leveling, or a change in drying time.

That does not mean something is missing from the paint.

Artists’ tube oil paint is a complete formulation. It does not require medium to become paint, to dry, or to form a paint film. The manufacturer has already made decisions about pigment, binder, pigment concentration, consistency, and, where used, stabilizers and other additives.

When you add medium, you are not completing the paint. You are reformulating a finished product on the palette.

That may be exactly what you need. No manufacturer can formulate one tube color to provide every handling property required by every painter and every technique. But once you modify the paint, the important questions are not simply whether the medium makes the paint feel better.

What are you trying to change? What are you adding to accomplish it? How much are you adding? What leaves the paint as it dries? What remains? And do you need that change throughout the painting or only in a particular passage?