We have made a tool to speed up applying mortar to top of the block for the next row. This is slightly complicated in that there are only narrow rims on the blocks to put mortar on and large holes to fall into. An additional complication is the Re-bars running up the center of each hollow, so the tool had be open ended to allow use without having to lift over the top of every bar.
The tool provides two slots a front and back to fill with mortar and trowel off level with the sides, this gives a fixed mortar bed of 12 mm. The spacers continue up the face of the previous block on the row to provide a per-pend joint.
Home-made-mortar-application-Tool
Mortar-Tool-On-blocks
Mortar-Tool