A pneumatic dispenser for dispensing viscous material, for example, mastic caulk, from a container is described. The dispenser comprises a fluid supply arrangement for accepting a dispensing nozzle of the container and providing a flow of pressurized fluid to the dispensing nozzle to enable the material to be dispensed as a spray. A moveable member can be used to control the flow of pressurized fluid, for example a member disposed on a cap for closing a container containing compartment of the dispenser and/or a moveable member disposed around the dispensing nozzle. The arrangement of the fluid supply arrangement allows for convenient control of the pressurized fluid flow for spraying the material. Also disclosed is a dispenser with a readily exchangeable pressure application interface for applying a dispensing pressure to the container, enabling the dispenser to be used with both cartridge and foil pack containers.