Stitching faces - using stitch as line

Detailed stitching of faces might involve cross-hatched areas, as in this drawing by Gwen Buchanan -

Engravings usually use cross-hatching for shading -

Detail from an etching by Barocci (via)

or parallel lines, or lines of different weights -

Van Dyck (rendered by Lucas Vorstermans) (via)

Here's how Audrey Walker uses cross-hatching in stitch - very densely, built up in layers -

Detail from Beach Woman, 1995 (via)

And in this self-portrait (via) she uses lines of a different sort -