Under the theory of moist wound healing, when the CMC hydrophilic granules from hydrocolloid meet exudates from the wound, a gel could be made on the surface of the wound which could make a durative moist environment for the wound. And the gel is non-adhesive to the wound. Hydrocolloid dressings are generally used for moderately draining wounds. What makes hydrocolloid dressings unique is their soft, absorptive wafers that become gel-like over time to help with the healing process. Hydrocolloid dressings is a kind of elastic dressing made of pressure sensitive adhensive with CMC (Carboxymethycellulose) hydrophilic granules. It forms a gel when in contact with wound surface, usually formulated with an occlusive, water-repellent backing and promote an acidic and hypoxic wound environment.