steam curtain

steam curtain

An apparatus consisting of perforated pipes, located at the proscenium of a theater, from which steam escapes; used to block or partially obscure a view of the stage.
References in periodicals archive ?
Also still in place are perforations for a steam curtain. They run across the front of the stage, parallel to the footlights, and allow a curtain of steam to fill the proscenium arch, enabling the Rockettes to make appearances shrouded in mist.