How to use soapnuts in your laundry: So how does it work? You pop a few shells in a washbag, put it in the drum with your clothes and wash as normal. The soap nut shells release saponin (soap) when it comes in contact with water. The saponins then circulate as a natural surfactant (surface active ingredient / detergent). They break down the surface tension of the water and oil in the wash reducing the surface tension of the water aiding it in freeing dirt, grime and oils from clothes. Essentially this is how chemical detergents clean our clothes...but now you can do it without chemicals!