Usually using alot of the exotic butters will yield a softer bar of soap. (i.e, shea, mango). The higher the percentages of the "soft" oils such as avocado,Almond, soybean oil, canola oil, will result in a softer bar. The thing is, using higher percentages of these softer oils, you get zilch for lather and the soap is soft and mushy, not real desireable traits for a bar of soap.