As part of an actor's make-up, it is often used to make a person appear older.
[2] Bald caps may be purchased ready-made or be constructed on-site by a make-up artist,[1] who applies several layers of liquid plastic (such as latex) to a pattern made by covering the actor's head in clingfilm.
[2] Bald caps used in the theatre are made of thicker rubber, intended to be put on and off rapidly and multiple times.
[1] Coarser and more unrealistic bald caps are sometimes also used as part of a clown costume.
This trick received notable use in the "Earthanasia" episode of the British comedy program, The Goodies.