Samurai Thunder Soap is the ideal detergent for denim lovers. The natural soap is made using a recipe handed down from 1918. The base is soybean oil, a by-product in the production of soy sauce. Thunder Soap has a pure soap content of 99.9% and reliably and gently removes bacteria and dirt from your favorite selvage jeans and other indigo dyed garments. The mild care creates a soft patina that is full of character. The soap is all-natural and environmentally friendly.