A student sent me the following message: “I have ended up, in one image, having a lot of space that could go dark with a brush pen. Is it a good idea to blacken all the space, or is there a way to develop dark space without actually heavily blackening it?”
Without seeing the image in question, I can say a few things. First, maybe some empty space is OK. As for creating dark areas, a solid fill is not as interesting to the viewer as something with a bit of texture and variety. In my sketch of Servino’s restaurant, I used a black Pentel Brush-tip pen to create dark areas that allow some of the white paper to show through here and there, as well as a variety of strokes and dabs.
The black stripes in the awning were each made with a single stroke, using the side of the brush. This “dry brush” effect relies on the texture of my paper: Stillman & Birn Beta series (Extra heavy weight, Rough Surface.)
If you want to slightly darken a large area, such as the doors and windows under the awning, scribble some water-soluble pencils in one or more colors and create a wash with your water brush. This is a quick way to create depth, moving the darker areas to the back, and allowing the “unwashed(?)” areas to have more focus.