From Tonal Strip to Tonal Drawing

In this post, I introduce the tonal strip. This isn’t just an exercise but is also useful for reference when deciding on which grades of pencil to use and you’ll find it refines your technique - whilst also discovering that it’s important to begin a drawing with the H grades before adding the darker layers with softer grades.

In Exercise 5, you’ll be asked to make a tonal strip, much like the one shown below and this is achieved by using the continuous tone technique. This creates a smooth flat square of graphite for each pencil grade, which shows the increasing depth of tone as pencil graded move from hard to soft

A tonal strip of hard to soft grades of pencils using Faber Castell 9000 pencils on Fabriano watercolour paper. This strip shows the maximum value of each grade of pencil from 3H -the hardest and lightest tone, to 5B - the softest and darkest tone

On the image below I show a different approach: with a the graded tonal strip. You may want to try this exercise out as well but be warned that it tale time to do it properly.

A graded tonal strip in the front pages of my Etchr Sketchbook. The approach of using hard to soft grades in this strip is the same as above but this time, instead of having a square showing the maximum tone for each pencil grade, the tonal value for each pencil is also adjusted and lightened by easing the pressure of the pencil on the paper.

Understanding which grades to use—and why—is essential in tonal drawing. Choosing the correct range of pencils, combined with the right technique, determines how successful the drawing will be. The correct approach allows us to create subtle tonal variations between different parts of a plant, while also achieving a smooth finish.

For example, a pale flower will require harder grades than a darker leaf or stem. A tonal drawing should not resemble a sketch made with outlines, but instead should have a three-dimensional appearance with little or no reliance on line. This effect can be difficult to achieve if the wrong pencils are used.

In this white anemone WIP, harder grades such as 6H–H are used for the petals, while the darker leaves and flower centre require a broader range, for example 4H to 2B. It is still important to use hard grades underneath the softer ones to minimise the grainy appearance of graphite. For the darker areas, a sequence such as 4H, 2H, HB, and 2B can be layered effectively.From your tonal strip, you’ll know that when hard grades are used for the pale petals, the maximum tone will never become too dark, since the H grades are naturally limited in value. You can also vary the pressure of your pencil to create subtle shifts in light and shade.

Light (H) to Dark (B); Avoiding a 'grainy' finish

One of the most common problems in tonal graphite work is a grainy appearance, where small white flecks interrupt the smoothness of the drawing. This usually happens when pencils that are too soft are used too early. A lack of patience can also play a part—students often move quickly to softer grades without first establishing a sufficient base. Remember, layering graphite takes time if you want to achieve strong, even results.

From your tonal strip exercise, you’ll have noticed that it’s much easier to create a smooth finish with a hard H grade than with a softer B grade.

To avoid the grainy look, always begin with a clean base layer using H grades—something like a 4H works well. How dark your subject is will then determine how many additional grades you need to layer afterward.

Why Pencil Grades Behave Differently

Pencil “lead” is not lead at all, but a mixture of graphite and clay, with a little wax or binder added by some manufacturers. The difference between hard (H) and soft (B) pencils comes down to the ratio of graphite to clay:

Hard grades (H, 2H, 4H, etc.) contain more clay and less graphite. The clay particles are small and compact, which means these pencils make lighter, finer, and cleaner marks. They’re excellent for light tones and for building smooth base layers.

Soft grades (B, 2B, 4B, etc.) contain more graphite and less clay. With less binder, the graphite particles are larger, so they deposit more material on the paper surface. This creates darker, richer tones, but also makes it harder to achieve a perfectly smooth finish without careful layering as the larger particles catch on the indents in the paper. thats why we need a hard layer first.

Mid-range grades (F, HB, H, B) balance both materials and are often used as transition pencils when moving from lighter to darker areas.

So, when you move from light to dark (H to B), you’re really moving along a scale of clay content to graphite content. This is why building a base with H grades first is crucial: the clay-rich layers fill the paper’s texture and give the softer graphite something smooth to sit on, preventing that patchy or grainy look.

Sharpening and Pencil Control

Using the correct pencils—and keeping them well sharpened—enables far greater clarity in your drawings. A pencil that is too soft and slightly blunt will make it very difficult to achieve the precision required for a botanical tonal drawing, where clean, accurate detail is essential.

On the other hand, over-sharpening a hard grade pencil can cause it to scratch the paper surface, which not only damages the sheet but can also leave unwanted marks that are hard to blend.

If a pencil isn’t sharpened properly, it will struggle to reach into the small indentations of the paper’s texture, resulting in fuzzy or untidy edges. For the best results, keep a fine but slightly rounded point—sharp enough for accuracy, but not so sharp that it risks scratching. Try dulling the tip slightly on spare paper before committing to adding tone to a drawing and tweak the tip on fine grade class paper to maintain the sharpness.

This tonal dissection drawing of a Hellebore by Polly Sutherland, demonstrates clarity in the reproductive parts, this requires well sharpened pencils and a magnifying glass! blunt pencils or pencils too soft it will not achieve such clarity

Control the Pressure: Avoid the Shine

Never apply too much pressure when laying down graphite. If you do, the drawing can become shiny, especially when softer grades are used. Worse still, the wax content in the pencil can form a slick layer that prevents further layering—the surface begins to resist, and new graphite will simply roll off like dust.

The secret to avoiding shine is to use a light touch and build up the tones gradually . Keep working in thin layers until the correct depth of tone is achieved, rather than trying to reach it too quickly with heavy pressure. When using light pressure it is easier to create a smooth finish too and with continuous tone - not pencil motion marks will be visible.

If your subject is especially dark, it may be worth switching to Pitt Graphite Matt pencils for the later layers. These are designed to reduce shine and will help you maintain a rich, velvety finish in the deepest tones.

A dark apple started with hard grades, which transitions through the mid grades and finishes with Pitt Graphite Matt pencils

Stages of a dark shiny apple

Final Thoughts

After reading this blog post, I hope you can see the benefit of spending time on the tonal strip exercise. It quickly reveals whether your technique needs adjustment—if your gradations are uneven, the tones won’t flow smoothly, and you may notice patches or visible pencil strokes.

Achieving a flawless tonal strip doesn’t happen overnight; it takes patience and consistent practice. Think of the tonal strip as the foundation of your botanical drawings—the stronger your foundation, the more beautifully your work will grow.

Heres a short video of me discussing and demonstrating the graded tonal strip