Product Overview How to Use At a Glance Ingredients Other Details Philip Kingsley Elasticizer (5.07 fl. ^46% REDUCTION IN BREAKAGE AFTER ONE USE - INDEPENDENT INSTRUMENTAL TEST. Some like the luxuriousness of leaving one on overnight to lock in moisture, so while theres no hard and fast rule, its important to take your hair type and the moisture level you're looking for into account. Please try again. Leave on for a minimum of 20-30 minutes. }) I've tried lots of cheaper conditioning treatments but not seen any real improvement so far.