This is an old fashion pen and ink drawing which is uniquely done. 4 layers with cross-hatching done perfectly. Pen and Ink Crosshatching master illustrator Dan Nelson describes and demonstrates his refined cross-hatching technique.
Hatching – This drawing technique uses a series of parallel lines drawn close together, in the same direction, which gives the appearance of value.
Crosshatching – Similar to hatching only you draw multiple layers of hatch lines at different angles that overlap one another.