Walnut Oil is extracted from the seeds of the walnut tree and used as a painting medium for oil painting.
It dries slower than linseed oil, but is less prone to yellowing after drying, therefore more suitable for light color paints.
Since it is extracted by cold pressing, it dries slower than linseed oil but is less prone to yellowing.
In Renaissance Italy, the oil from local walnuts was favored and was added to painting mediums for oil painting as well as to mediums for tempera painting.

※Yellowing = paint turns yellowish over time.

◼️Drying time
Fast (Linseed oil) > Slow (Poppy oil ≒ Walnut oil)

◼Yellowing
Strong (Linseed oil) > Weak (Poppy oil ≒ Walnut oil)