The secret to old fashioned lye soap’s cleansing power is in it’s high lye content and lack of exotic oils. We see this benefit mainly in the area of laundry and general household cleaning recipes. A majority of the recipes available for homemade laundry detergent call for the use of castile soap or some other “super-fatted” soap. (Note: Super-fatted is a fancy soap-making term that basically means…soap made with a lower percentage of lye so as to be ultra moisturizing for the skin and/or hair.)