Castor oil is a vegetable oil pressed from castor beans. Castor oil is a colourless to very pale yellow liquid with a distinct taste and odor. Its boiling point is 313 °C (595 °F) and its density is 0.961 g/cm3. It is a triglyceride in which approximately 90 percent of fatty acid chains are ricinoleates. Oleate and linoleates are the other significant components.
Castor oil and its derivatives are used in the manufacturing of soaps, lubricants, hydraulic and brake fluids, paints, dyes, coatings, inks, cold resistant plastics, waxes and polishes, nylon, pharmaceuticals and perfumes.
Castor oil is used as a bio-based polyol in the polyurethane industry. The average functionality (number of hydroxyl groups per triglyceride molecule) of castor oil is 2.7, so it is widely used as a rigid polyol and in coatings. One particular use is in a polyurethane concrete where a castor-oil emulsion is reacted with an isocyanate (usually polymeric MDI Methylene diphenyl diisocyanate) and a Cement and Construction aggregate. This is applied fairly thickly as a slurry which is self-levelling. This base is usually further coated with other systems to build a resilient floor.
It is not a drying oil, meaning that it has a low reactivity with air compared to oils such as linseed oil and tung oil. Dehydration of castor oil yields linoleic acids, which do have drying properties. In this process, the OH group on the ricinoleic acid along with a hydrogen from the next carbon atom are removed yielding a double bond which then has oxidative cross-linking properties yielding the drying oil.