Wet mops are used with cleaning or disinfecting solutions. They come in three main types. The first type of wet mop uses cleaning pads that have been pre-saturated with a disinfecting solution, while the second type feeds cleaning solution to the mop head through a gravity-fed reservoir. A third type of wet mop pairs with a bucket system to clean large floor areas. This type typically has a large mop head with long, ribbed strands. Wet mop heads are made out of highly absorbent materials such as cotton and polyester. Polyester resists deterioration, which makes it an ideal wet mop head material for use in cleanrooms.