A stencil printer for printing viscous material on an electronic substrate includes a stencil having apertures formed therein, and a print head positioned over the stencil and configured to deposit viscous material within the apertures of the stencil. The print head includes a housing defining an elongate chamber, a source port defining a passage having an inlet positioned to allow viscous material to flow into the elongate chamber, a pair of blades defining a slot that provides an outlet from which viscous material can flow out of the elongate chamber, an elongate plunger movable in the elongate chamber to reduce a volume of viscous material within the elongate chamber, and at least one sensor to detect pressure of the viscous material within the elongate chamber.