CLING WRAP
Cling wrap is excellent for creating roughly textured surfaces that can be used to represent natural forms such as (but not limited to) foliage, bark, or stones. The benefit of this particular textured effect is that it usually adds a great deal of depth to your watercolors.
To apply, add the cling wrap over a wet (not just damp) color wash where you would like to incorporate this texture. The cling wrap can then be pushed around to create the shape, size, and direction of pattern you desire. Ideally, the wrap should be removed after allowing the watercolor to dry completely.
In this study of a shoebill bird, I arranged the plastic wrap to create a variety of shapes in the background watercolor wash.
As with a salt wash, if the texture effect is too strong, another wash of color can be glazed of the top to soften the look. In this case, I did feel as though the cling wrap texture was distracting from my subject. By glazing over the background with one unifying color (Thalo Blue), I was able to put the focus on the shoebill and set him in an environment.
