Every watercolor artist has experienced an accidental back run—when a drop of water creates a “bloom” in a freshly painted wash. But for painting leaves, flowers and trees, I like to use intentional back runs to create mottled color, a feeling of foliage and the appearance of uneven lighting conditions.
Creating a back run is quite simple. Start by putting a wet–in–wet wash down in a specific shape. Just as the shine of the wash begins to fade, simply drop water onto the paper from your brush, your fingers or a spray bottle. You can’t control the direction of the back run, but you can control the texture of the edges. For a soft edge, drop the water as soon as the shine begins to fade. For a harder edge, drop the water when the wash is almost dry.