As you spend more and more time drawing, there usually comes a point when contour drawing isn't enough. You can set down lines that perfectly describe the shapes in front of you but you become interested in giving your work dimension and exploring the effects of light and shade. Several people have reached that point recently and written asking me to talk discuss the whys and wherefores of cross hatching. let me try.
Cross hatching is quite miraculous. How is it that black ink lines on white paper have the ability to create an infinite number of shades of grey, to evoke all the colors of the rainbow and to suggest textures and materials and varied as silk and stone, glass and schnauzer hair?

The first thing to do is to get in the groove. Practice drawing lines until you can lay them down in fairly predictable parallel strokes. Do it in boring practice sessions or just start working them into your drawings. Try greying gradations, filling boxes from pure white to solid black — space the lines far apart in the first box, then halve the distance in the second box, then halve it again in the third and so on until your final block is completely black. Next, try crossing your vertical lines with horizontal ones, weaving darker and darker gradations. Then lay a diagonal set of lines over the grid, upper left to lower right, then cross back upper right to lower left. Try keeping them as regular and even as you can, so you can create various sorts of grey with various sorts of combinations of lines. Don't make yourself nuts just experiment with lines at 45 and 90 degree angles.
The next things to consider: What do these shades of grey represent? The answer seems to fall into three main effects: Tone, color and texture. You can decide that darker greys mean things in shadow, or that different greys represent different surface colors, or that the lines represent different textures.

These drawings (by Guptill — see below*) are basically about light and dark. The lines tell you the volume and direction of the light on the object and that's about it.

These lines tell you a lot more about the materials the objects are made from; straw, wood, wicker, etc. all accomplished with crosshatching various sorts of lines.

In this drawings, my pal Tom Kane uses lines to suggest different colors in a girl's kerchief.

But here he uses the same sorts of lines to express the direction and shading of light on a girl's hair.
As you can see, once you start introducing these tones, you have a lot more decisions to make. You aren't just recoding shapes; you are expressing an opinion about what you found interesting in the scene.

Consider the differences that values and tones make in these three interpretations of a scene:the various choices evoke different temperatures, distances, moods and degrees of importance.

It's interesting to play around with line quality and stippling too: Consider the different feelings these drawings have because of the varying degree of regularity and the direction of the lines used in each identical composition.
My inclination is to avoid incredibly regular lines; they seem mechanical and inorganic to me. I lay down one value in the middle then go back and firth balancing areas with more or less crosshatching until I have described the effect I want. It';s all a matter of balance and crosshatching is pretty forgiving, If things feel off, just go back and hit your darker areas with a new layer of lines to get the emphasis right.
Like so many things in drawing, there aren't a lot of hard fast rules or rights and wrongs. Crosshatching is just another opportunity to record your observations, capture your feelings and have fun. And there's something about that hypnotic regularity of drawing parallel lines that is very soothing.

"Drawing is just an excuse to crosshatch"— R.Crumb
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* The greatest practitioners and teachers worked and published in the 19th century, when every day's paper was full of endless engraved examples of cross hatching. I have learned a lot from the publications of Watson Guptill, beginning with seminal works by Arthur L. Guptill himself, like Rendering in Pen and Ink and moving on to the less encyclopedic but crystalline Henry C. Pitz's Ink Drawing Techniques. I also love Paul Hogarth's Creative Ink Drawing. Many of these are still in print or can be picked up cheaply second-hand.