Sketching on toned paper is ideal for fast field work. Drawings done on mid-range gray or brown paper can help you to use a wider range of values (light to dark), and to place shadows and highlights more deliberately. Use the value of the paper as one of the values in your drawing. With a graphite pencil add lines and push darker values. Then add highlights with a white pencil and watch your drawing “pop”.
Start with paper that is a neutral color such as gray or brown and is mid-range in value. If it is too dark, your pencil lines will not show up. If it is too light you will loose the impact of the highlights you will add with white. There are lots of great colors of paper that are sold for pastel work and can be used for field sketching as well. I like the Canson mi-tientes paper. Try Oyster 340 (medium brown), Moonstone 426 (warm gray), Sky Blue 354 (blue gray), and Flannel Gray 122 (flat gray). It comes in big sheets that are impractical for the field but you can cut them to fit in your sketchbook and then glue them in place. Strathmore also makes sketchbooks filled with toned paper. These can be used as is or you can remove the sheets, cut them to size, and past them into your own sketchbook. Look for Strathmore Toned Tan and Toned Gray 400 series spiral bound sketchbooks. You can stick several sheets of pre cut toned paper, trimmed to various sizes in the back of your sketchbook. Use them whenever you want and then paste them in with a glue stick you carry in your sketch kit. A glue stick is also handy if you are traveling and want to paste ticket stubs and other items into your sketchbook to add an element of collage to your notebook.
Before sketching do a value study on the toned paper to help you determine where your paper color fits in your value scale. If it is lighter paper, you will make most of your sketch with your regular pencil and only add a little bit of a highlight with the white. If your paper has a darker value, you will be adding more steps of value with white. Make a little chart in the corner of the paper: make a box around bare paper and to one side of it extend boxes shaded progressively darker and to the other side, boxes lightened with white. It helps to think of “pushing” the darks into the crevices and shadows, and “pulling” the lights on surfaces that are bathed in sunlight.
Before drawing on toned paper, make a value chart to explore the range of darks and lights you can achieve on that kind of paper with the tools you have available.
Make sure that you take advantage of the value of the paper itself. It is easy to get working away and cover your subject with graphite or white pencil but make yourself leave sections of your drawing as blank paper. In this way you incorporate the value of the paper into your value scale. Just because a gull has a white breast does not mean that you should hit the entire breast with a white pencil. You can the value of the paper to represent the shadow on the belly. Similarly, you can use the value of the paper to represent the gulls back where it is hit by strong sunlight. To be successful, you must plan ahead.
Start with a line drawing of your subject. Then decide what areas you plan to let the value of the paper show through; this could be a shadow in a light area and a highlight on a dark area. Using your graphite pencil, push the shadows and darks. Now observe the shape of the highlights. Shape is the important word here, do not just start blending white across the highlights but think of the highlight as a shape. Carefully observed shapes of shadows and highlights describe the changes in the planes that cover the surface of your subject. Now for the fun part; while maintaining the blank paper, add the highlights with white. Pow! Your drawing pops off the page. Now stop drawing before you fill in all of the blank paper. Knowing when to stop is difficult; my advice is to stop before you think you are done instead of when there is no more room to add anything else.
Add white pencil to the highlights noting the shape of the highlighted area and leaving the rest of the chest unmarked to suggest shadow.
As an alternative to colored pencil, try light washes of watercolor or gouache but be prepared for the paper to buckle.One last advantage of sketching on toned paper in the field is that there is less glare off toned paper which is a relief if you are drawing in intense sunlight.