An even field of tone

Before you can grade tone you must be able to lay it flat. The enemies are visible rows (strokes laid side by side with gaps or overlaps) and dark stroke-ends (where the pencil stopped dead instead of lifting off). The cure for both is the same motion: each stroke overlaps the last by half, and the pencil leaves the paper like a plane taking off, so that the end of every stroke feathers to nothing.

Lay the first layer with the pencil on its side at one angle, covering the whole area. Lay the second at a different angle. Two light layers in different directions cancel each other's streaks. If it still shows rows, a third pass at a third angle will finish it. Do not reach for the stump; a stump makes a flat tone, but it also makes a dead one.

Practise on a two-inch square until it looks like a piece of grey paper. Then a four-inch square. Then a square with a hard edge on one side and a soft edge on the other.