Term: Drying Oils

Drying oils are vegetable oils that become dry to the touch under normal temperatures after being exposed to the air for a period of time. Drying oils do not actually dry in the traditional sense (that is, through evaporation of water or other solvents) but rather react chemically with oxygen to hardens to a tough, solid film.

Drying oils are the binder used to create oil-based paints and mediums. Oils can also be added to paint to modify its consistency, make a glossier finish, or extend the drying time. Using oils rather than solvents to thin paints prevents over thinning which is particularly useful in maintaining the flexibility of paints when working fat over lean.

Common drying oils include linseed (or flax seed), walnut, poppy and safflower. These oils have different drying rates, consistencies and color. Non-drying oils are mineral oils and vegetable oils, such as peanut oil and cottonseed oil, that do not oxidize and harden naturally. These oils should not be combined with oil-based paints.