Earthen hikizuri finish — dragged finish. You can get a similar effect from a wooden float, especially if it is given a slight curve. This was done with a hand-forged metal trowel with a slight curve. My boss ordered three different hikizuri trowels of varying metals, forging styles, and, therefore, prices. He let me use them to practice. Nice guy! It was trickier than I expected it would be, particularly to get a continuous equal effect across the whole wall, which was 6ftx6ft. Time = moisture suckage = must speed up!