drying oil

an oil that hardens when it is exposed to air, commonly used in paints and other coatings to make them dry and form a solid layer

Drying oil is a type of oil that hardens over time when exposed to air, forming a solid, durable surface. It is commonly used as a mixing ingredient in paints and coatings to help them dry properly. These oils improve the paint's consistency, flow, and finish, making them essential for creating long-lasting and protective layers on various surfaces.