If, like me, you’ve ever finished a watercolor painting and then wished you’d included a figure or some other detail, here’s a simple stenciling method for adding those elements while preserving the purity of your transparent watercolors.
Step 1: First, lay a piece of tracing paper over the section of the painting where you want to make an addition. Next, simply draw the desired shape over that spot so you’ll be sure it fits nicely into the space.
Step 2: Remove the tracing paper from the painting and tape it to a scrap piece of cardboard.
Step 3: Place a piece of see-through acetate or plastic (any color) on top of the drawing and then use a sharp knife to cut the shape out of the plastic-creating your new stencil.
Step 4: Position the stencil firmly in place on the painting (either by taping or holding it tight) and using a slightly dampened, fine-textured cosmetic sponge, carefully dab the open areas of the stencil.
Step 5: Wait a few seconds to allow the dampness to penetrate the watercolor paint, and then quickly rub the dampened area with a tissue to remove all or most of the paint from within the stencil shape. Repeat the process as necessary until you’ve removed enough paint to add color to the area. If the edge of the shape is too hard, try softening it with a wash of clear water.
Although staining pigment will leave a hint of color that can’t be removed completely, you can usually cover the area by repainting it.
Step 6: Remove the plastic stencil from your paper and simply paint in the figure. And voila, you’ve successfully added forgotten elements to your painting while retaining your transparent colors.
Note: I recommend practicing this procedure first on a discarded painting or scrap of paper before attempting it on a finished painting.