Hydrogenated castor oil is a white waxy solid derived from the castor bean (Ricinus communis) a fast growing species of flowering shrub. Likely a native to North-East Africa but now found around the world, these trees grow up to 4 meters tall with large, soft leaves and clusters of flowers containing rectangular seeds. The seeds, known as castor 'beans' are particularly rich in triglycerides, useful fatty acids also present in the body. To produce castor oil, harvested seeds undergo a process of drying, dehulling, heating and pressing to extract the oil. The raw seeds are highly poisonous due to the presence of ricin; the crucial heating process during oil production disables the ricin rendering the oil safe for use.

Using hydrogen gas, a catalyst such as nickel, and high pressure, plant oils can undergo a hydrogenation process whereby they change from a liquid into a solid or semi-solid state - becoming hydrogenated oils. The hydrogenation process allows oils to remain solid at room temperature - an everyday example of which is margarine. When used in skincare, hydrogenated castor oil's resistance to water and oil can help the skin retain moisture, leaving it soft and smooth.

Other names: Castor Wax, Glyceryl tris(12-hydroxystearate), Trihydroxystearin; Castor Oil, Hydrogenated