Raw black soap is generally made with plantain skins, a good source of Vitamins A and E as well as iron. Vitamin E is an antioxidant that helps your skin retain its health and moisture. Vitamin A keeps your skin young and fights wrinkles and spots. Iron may also strengthen your skin and hair.
Many types of black soap are made with large amounts of shea butter. A study published in the "Journal of Photochemistry and Photobiology" found that the caffeic acid in shea butter fights UV radiation. Using raw black soap may help protect your skin from sun damage.
Black soap has traditionally been used in Ghana and Nigeria to treat acne, oily skin and blemishes. This may be a result of the potash that gives the soap its black color.
Raw black soap is often used in shaving, to help fight eczema and psoriasis. As with acne, different varieties of black soap may have varying effects on skin impurities. However, the shea butter in the soap helps to moisturize and smooth skin, alleviating itching and other irritations.