Pomaderris Kumarahou, has a very high saponin content. Saponin is a surfactant, which means that it can foam into a lather, 100% naturally. Most soaps contain chemicals to do this. Kūmarahou was traditionally referred to as gum diggers soap, as the gum diggers of the 1800s would use kūmarahou and water to remove kauri gum or tree sap from their hands when they were working. This soap is beautifully soft, very healing and 100% natural.