Ayurvedic medicine has long used castor oil for lumbago, sciatica and rheumatism. In the Canary Islands the oil is used to prevent sore nipples in nursing mothers and is also rubbed onto their scalps to prevent post natal hair loss. In soap making, although castor oil would appear to require less sodium hydroxide, it sometimes requires more due to its high ricinoleic acid content. It's also a well-known super fatting agent and well suited for shampoo bars and skin-care products. Without other oils, it produces a transparent soft soap. In combination with over vegetable oils, however, it makes a wonderfully emollient, hard bar of soap. SAP value: 180.3. INCI: Ricinus communis (castor) seed oil.