Collodions are liquid preparations for external application to the skin. They are applied to cuts and abrasions. They are also used when prolonged contact between the skin and the medicament is required. Volatile vehicle is used in collodions that evaporate on application to skin, leaving a flexible, protective film covering at the site of application. Collodions are applied with a brush or rod. Collodion is a flammable, syrupy solution of pyroxylin (nitrocellulose) in ether and alcohol. It is of two types, namely flexible and nonflexible. The wound covering must be elastic to ensure that all layers constituting it are in close contact with the wound surface.