Abstract: A template device (12) for applying mortar to a surface of precast concrete block (10) of the like. The device includes a frame (28) which has an outline similar to the outline of the surface of a standard precast concrete block (10) upon which similar blocks are stacked during building operations. Walls (30) served to define openings in the template device which are substantially coextensive with the sections of the surface of the block upon proper placement of the device thereon. Cover members (36) of the frame are substantially coextensive with openings in the block to prevent waste of mortar into those openings. A guide (40) is provided to facilitate proper positioning of the device squarely on the a block (10) prior to the application of mortar thereto. The device (12) assists those skilled and unskilled in precisely controlling the thickness and placement of mortar on precast concrete blocks of standard sizes during building operations.