Abstract: A damper for an air passageway comprises a rigid carrier plate having opposed faces defined by a periphery with a shape generally corresponding to but smaller than the shape of a cross-section of the air passageway and formed of a material having a melting point above an activation temperature range; a heat-expandable sealing material mounted to at least one of the opposed faces of the rigid carrier plate and which is adapted to expand at a temperature in the activation temperature range; the sealing material, when activated, is adapted to expand radially from the rigid carrier plate to form an integral seal with the carrier plate. The heat-expandable sealing material can be integrally molded to the outer periphery of the carrier plate. A process for making the damper with integral seal is also disclosed.