Abstract: A collapsible wall closure for a dispenser nozzle comprised of a stiff but resilient tube section adapted to be bent over and latched in the bent position to provide a fluid tight closure of the nozzle by collapse of the tube wall. The interior of the nozzle tube is undercut in the region of the wall collapse on either side of the tube along the fold line of the tube, in order to provide complete sealing collapse of the tube wall in the bent position. The undercuts are comprised of shallow grooves extending axially along the tube interior thinning the tube wall thickness in the region of the wall collapse. A pair of closures are incorporated in a cap closure particularly adapted to an ammonia hydroxide container for connection to vapor-type diazo reproduction machines.