Abstract: A single facer is provided with an adjustable width glue means including an elongated floating shoe having doctor blade means biased toward a glue applicator roll and movable away from the latter to form a metering gap through which glue exits from an elongated fluid cavity of the shoe as a thin film on the applicator roll. The shoe also includes an elongated fluid manifold which receives glue under pressure from a glue supply. A plurality of passages formed in the shoe and spaced along the length thereof interconnect the fluid cavity and manifold so that glue flows to the former from the latter. Longitudinally adjustable side dams are provided for the cavity and manifold to control the width of the glue film. A cleaning fluid introduced at the ends of the manifold flushes through those passages outboard of the dams and exits at the ends of the cavity to prevent build-up of glue in the shoe.