Abstract: A flat plastic bag of generally triangular configuration is factory-filled with a measured amount of dental impression powder. The sealed bag has a frangible seam pierceable intentionally by a conventional syringe nozzle to add water when ready to mix. A corner of the bag opposite this seam is severed, when desired, to for controlled dispensing of the contents into an impression tray. In use, a measured amount of water in the syringe bulb is introduced to the bag by insertion of the bulb nozzle into the seam margin. Then the bag is gripped between the pierced opening and the top of the water and powder contained in the bag. Then the water and powder are mixed by kneading the bag. When mixing is complete, the dispenser corner of the bag is severed, and the material is squeezed into the impression tray. Before introduction of water into the bag, the bag is essentially flat except where deformed by the powder itself, thus minimizing air in the bag.