http://en.wikipedia.org/wiki/Hatching

--------------------------------------------------
Note added at 10 minutos (2011-12-11 15:21:05 GMT)
--------------------------------------------------

http://drawsketch.about.com/od/drawingglossary/g/crosshatchi...
Definition: Crosshatching is an extension of hatching, which uses is the use of fine parallel lines drawn closely together, to create the illusion of shade or texture in a drawing.
Crosshatching is the drawing of two layers of hatching at right-angles to create a mesh-like pattern. Multiple layers in varying directions can be used to create textures. Crosshatching is often used to create tonal effects, by varying the spacing of lines or by adding additional layers of lines. Crosshatching is used in pencil drawing, but is particularly useful with pen and ink drawing, to create the impression of areas of tone, since the pen can only create a solid black line.

Alternate Spellings: cross-hatching


--------------------------------------------------
Note added at 13 minutos (2011-12-11 15:24:06 GMT)
--------------------------------------------------

Cartoonists and comic book artists, which are different, both use crosshatching to distinguish variations in tones and shades. Pick up any beginner book on learning to draw cartoons or comic book characters, and you will see that they teach this technique.