QWISO, or Quick Wash ISOpropyl, is a solvent-based extraction method for making concentrates. The only difference between RSO and QWISO is the original extraction method for RSO used naphtha (hydrocarbon) instead of isopropyl. In fact, the recipe for RSO on Rick Simpson’s website is actually a QWISO recipe. If you make RSO using isopropyl alcohol, you are making a QWISO concentrate, sometimes called isopropyl hash oil QWISO hash oil