Vertical L-shaped steel channels located on the upstage side of the proscenium opening and extending up to the gridiron. The smoke pocket serves two purposes: 1) to provide a guides for the edges of the fire curtain, and 2) to provide a seal (though rarely air-tight) to prevent smoke from a fire from moving from the stage area into the auditorium.
The upstage side of the smoke pocket is often used instead of the plaster line as a basis for which all measurements are taken, as temporary show decks and scenery cannot interfere with the operation of a theater's fire curtain.
The upstage side of the smoke pocket is often used instead of the plaster line as a basis for which all measurements are taken, as temporary show decks and scenery cannot interfere with the operation of a theater's fire curtain.