The duration for which you should leave the Vitagenic Jelly Mask on your face can vary based on your skin type and the specific needs of your skin. However, based on the reviews, it is generally recommended to leave the mask on for about 15-20 minutes. This allows enough time for the essence to be absorbed and for the mask to provide its intended benefits, such as pore tightening and moisturization. One reviewer mentioned they keep the mask in the refrigerator and use it after showering and removing excess oil, which suggests a post-cleanse application for optimal results.