The major difference between clear and black castor oil, besides the color, is that impurities are added to black castor oil. Natural castor oil is actually pale yellow in color due to its iodine content. The clear variety is achieved by filtering the castor oil to reduce the iodine content.
Natural castor oil is cold pressed without the use of heat when it is removed from the seed. This process ensures that the oil is not degraded. To achieve the dark color in black castor oil, ash from roasted castor beans is added to the mix. This dark oil is often referred to as Jamaican black.
Black castor oil facilitates hair growth by promoting blood flow to the scalp when applied topically, according to NaturallyCurly.com. It is particularly effective for kinky and wavy hair but works on all hair types, as it adds nutrients to hair follicles and moisturizes dry locks.
Clear castor oil is used to stave off mold in packaging and as a preservative for foods such as candy and flavorings. It may also be used for medicinal purposes, including the relief of constipation or back pain. However, it can cause problems; stomach upsets and skin reactions are typical side effects of taking or applying castor oil.