Six families of mark

Hatching is tone made from line. Parallel hatching (one direction, even spacing) is the workhorse: flat planes, skies, the shadow side of a wall. Cross-hatching layers a second direction over the first and is how the etchers counted their way to a dark. Contour hatching curves with the form and makes a cylinder read as round, a tree trunk as a tube, a cloud as a mass. Scumble (loose overlapping circles) is Corot's foliage and his soft ground. Stipple is dots, slow and precise, for stone texture close to the eye. The broken line is a Prout contour that stops and starts to say old and weathered.

The direction of your hatching should follow something: the plane it sits on, the form it wraps, or the light. Hatching that runs the same way across every surface flattens the picture. Hatching that changes direction at every plane change builds it.

A rule that keeps hatching clean: hatch in one direction until the whole area is covered, then decide whether it needs a second layer. Do not weave back and forth.