If you're painting on a canvas with a relatively coarse grain or weave, for instance cotton duck canvas, sgraffito can be used very effectively with this. When a layer of paint is dry, you paint over with a new color and while this is still wet use the side of a large painting knife or palette knife to scrape off most of the paint.
The new color will remain in the lower "pockets" of the weave, as the photo shows, because the knife doesn't reach into these. If you want to remove more of the color, dab at the painting with the cloth. Use an up-and-down motion rather than moving it from side to side, which will smear the paint across the canvas.
This technique can be used over a whole canvas, or merely a small section. A variation is to wipe a painting knife, with only a little paint on it, flat across the canvas so the paint goes only onto the top of the canvas weave.
