[2] During the production of the 1973 film The Exorcist, make-up artist Dick Smith used trichloroethane, a liquid, to achieve the effect of welt-like letters being raised on a foam latex stomach.
[2][3] He went on to develop and refine air bladder effects for the 1980 film Altered States,[2][4] which depicts lumps rippling beneath a character's skin.
[5] Smith continued to implement air bladder effects in other films, including Scanners (1981)[2] and Spasms (1983).
[3] Rick Baker, who worked as Smith's assistant on The Exorcist, made use of air bladder effects in combination with other mechanisms when creating a werewolf transformation sequence used in An American Werewolf in London (1981).
[2][6] Baker and his protégé, Rob Bottin, also incorporated air bladder effects for a werewolf transformation in The Howling, also released in 1981.