What Does L'Oreal Professionnel Serie Expert Curl Expression Hair Mask Do? Curl Expression intense moisturizing mask - designed to treat curls and kinks in a professional way. It deeply hydrates and pre-detangles curls and kinks for a free-flowing result with a natural feel. Hair is 2 times brighter and frizz is controlled. Hair is shiny and frizz is controlled, with a free-flowing result and natural feel. It deeply moisturizes and pre-detangles curls and coils. How to Apply L'Oreal Professionnel Serie Expert Curl Expression Hair Mask? After shampooing, apply to towel-dried hair and leave for 10 minutes. Then rinse thoroughly.