CLEAN? What do you mean? You probably mean that all the dirt and germs are gone. It's easy to see if your hand cleaner removes the visible dirt, but what about removing the bacteria - making your hands sterile?     What you need: a means to detect bacteria on your hands. Then you should try to clean your hands with various soaps, rinses, etc. After each wash you will print your finger on a sterile nutrient agar surface.   The germs printed from an unwashed hand should grow up really scuzzy (←top); but if your hand cleaner did sterilize, then nothing at all should grow. Try all sorts of washes including alcohol, and dilute bleach (see webpage safety instructions) - but after each "treatment" you MUST rinse your hands in sterile water to get rid of the "cleaner" before you print your finger.   You will show that you can never get rid of all the bacteria, nor do you want to! (Why not? That's what Sally doesn't know.) Read the webpage below: For more details: www.science-projects.com/CleanHands.htm