Castor oil is obtained from the seed of Ricinus communis L. by pressing without added heat (cold-pressing). If the product is re-pressed, but with added heat (hot-pressed), it provides a castor oil known as '1st pressing castor oil'.
The castor oil plant, a herbaceous, frost-sensitive annual with arborising branches, grows to a height of approx. 1-3 m, in temperate latitudes. This plant, which is native to warmer regions, can grow to a height of 12 m and lives for approx. 4 years. Seeds from the plants were found in Egyptian tombs dating back to the 4th millennium B.C. However, it is not clear whether the castor oil plant originated in India or Africa. Today, this plant is of economic importance and it is distributed around the world. However, it tends to favour tropical and sub-tropical areas.
The pink ovary containing the seeds is surrounded by a hard, reddish-brownish marbled shell. The seed has a 40-50% oil content. Cold-pressed castor oil is a pale yellowish, indigestible, viscous, non-drying liquid with a faint characteristic smell and a mild taste, but one that later becomes an unpleasant, irritating taste, whereas heat-pressed 1st pressing castor oil has a marked yellow-brown colour.
Castor oil consists mainly of oleic, linoleic, palmitic and stearic acids, along with 80-85% ricinolic acid glyceride, which gives castor oil its purgative action. Castor oil is thus used as a purgative in human and veterinary Medicine. Since the viscosity of castor oil is, to all intents and purposes, consistent and since it acts as a strong adhesive, it is used as a lubricating oil for aircraft, ships, jet engines, hydraulic pumps and brake fluid, also used as a softener in the plastics industry, as well as in the capacity of a raw material in dye (printing dyes, lithographic varnish, oil-cloth) and paint production (clear and enamel paints), and in the rubber, textile, leather, plastics (polyamide 11) and detergent industries, where reprocessed castor oil (e.g. Turkey red oil = sulphated castor oil) is used once again.
Castor oil is used in specialised industries both as a base for the synthesis of sebacinic acid and 12-hydroxy stearic acid and for the production of linoleum floor coverings. In the decorative cosmetics industry, castor oil is used as a base for lipsticks and eye-liners. Hair shampoos contain =30% castor oil.
INCI Name: Ricinus Communis Seed Oil