Main Ingredients Vitamin C brightens and evens your complexion while fading pigmentation and brown spots. Also, it boosts the skin's own collagen production. How to use Apply TONYMOLY Master Lab Intensive Brightening Vitamin-C Sheet Mask to your clean, dry skin. Let it act on your skin for 20 to 30 minutes. When removing it, gently pat the excess serum on your face and neck until it is fully absorbed. As an extra tip, for a refreshing effect store your mask in the refrigerator.