When I refer to directional hatching, I am talking about lines that follow the relative direction of the contour (fat, skin, muscles, bone, etc.). Your hatched lines can follow these directions with intent. Imagine an ant crawling across the abdomen of the model. The ant would not travel in a straight line; nor would he be free of any bumps or pot holes while strolling across this tundra. In fact, it would be as though he was traveling over a vast, unique landscape, carved out by years of erosion. He would encounter a long axis around the pelvis, only to be met by the pelvic bone or a fold of skin, which would stop him and suddenly change his direction. The abdominal muscles would be like a series of rolling and undulating hills he would have to traverse. Your lines (and hatches) can follow these same paths, these same changes in direction, and give a better sense of the fullness of the form you are trying to represent. Cross-hatching
comes into play when you go back and try to see where there are “breaks” or other shapes within the contour shapes you’ve just defined. Lay the lines over the initial lines as you discover new shadows and new smaller planes within planes. This will make your drawings feel more sculptural and heavy.
Notice on the figure shown here how the lines change direction as I find a new plane.