A screen printing device is disclosed. The screen printing device includes a screen printer workstation having a work path. The work path has an input end, an output end, and a conveyor for transporting a workpiece between the input end and the output end. A stencil assembly is adapted to engage the workpiece as the workpiece is transported between the input end and the output end. The stencil assembly includes a stencil having an endless loop. A method of applying a substance to a workpiece using an endless loop stencil is also disclosed.