If you've done any drawing then this technique will be familiar -- in fact it is best suited to pastel pencils or hard pastel sticks. Hatching is simply a set of parallel lines, preferably fine lines (hence the pencil) drawn closely together. Cross-hatching is just the next step, drawing a second set of lines at an angle (most often at right angles to the first set).
This method is especially useful in pastel painting for the initial blocking in of a painting -- it allows you to experiment with color and tone in a loose, flexible way without fully committing to a final composition.
Tip: You can use this method to create a sense of form and shape by varying the direction of the cross-hatching.
