African 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. 

Reduces Skin Irritation

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.

PS: Raw black soap scent may be off-putting to some.