Cork grease is a lip balm-like grease for woodwind and reed instruments such as saxophones, clarinets, bassoons, and oboes. It is used on the corks to make putting the instrument together possible without damaging the cork and therefore possibly damaging the instrument's barrel. Cork grease also acts as a preservative, keeping the wooden cork moist and thick, in turn ensuring a good seal between parts of the instrument so that no air may leak through joints upon playing. Cork grease can help woodwind players adjust their instruments' tuning pieces (e.g. barrels, necks, bocals, staples) in respect to their pitch.
Cork grease is made with ingredients such as elm extract, organic sunflower oil, coconut oil and hemp seed oil. In past it was made from animal fat. It isn't toxic to humans.