The Nigerian black soap made by Tropical Naturals in Lagos, and probably the best-known African black soap in the world. A single bar that replaces shower gel, shampoo and shaving cream.
What African black soap actually is
This is the genuinely interesting part, and it explains the colour.
Traditional West African black soap — ose dudu in Yoruba — is made by roasting plant matter to ash and using that ash as the alkali. Cocoa pods, plantain skins, palm bunches and shea tree bark are burned; the ash is steeped in water; the resulting lye is cooked with oils and butters until it saponifies.
Every soap on earth needs an alkali. Industrial soap uses manufactured sodium hydroxide. Black soap uses potash made from burning agricultural waste — which is where the whole method comes from, and why it was possible long before there was a chemical industry.
The colour is the ash. Nothing has been added to make it dark, and that is why the shade varies from batch to batch. A perfectly uniform black bar would be a suspicious one.
Two things to know before buying
It contains honey, so it is not vegan. Honey is one of the listed ingredients, along with shea butter, palm kernel oil, cocoa pod ash, camwood (osun, which gives the name), lime juice and aloe.
It contains fragrance. Dudu-Osun is perfumed, and the parfum is a declared ingredient. If you are buying black soap specifically because your skin reacts to scented products, this is not the one — fragrance is the most common cause of cosmetic contact allergy, and natural or not is beside the point.
Shea is not a walnut
This soap is often listed with shea butter obtained from "the fruit kernels of shea walnut". Shea is not a walnut. It comes from Vitellaria paradoxa, the karite tree of the West African savannah, which is in a different family entirely. It is still a tree-nut derivative, which matters if you have a nut allergy — cosmetic shea butter is refined fat with very little protein and reactions are rarely reported, but it is worth raising with an allergist if yours is severe.
It is a true soap, and true soap is alkaline
Worth being straightforward about. All real soap is alkaline — typically pH 9 to 10 — while healthy skin sits around pH 5. That is not a fault of this soap; it is what soap is, and skin restores its own pH within an hour or two.
But it does mean black soap can be drying, particularly on the face and particularly in hard water. Many people love it and some find it too much. Try it on your body before your face, and moisturise afterwards.