Circulism Technique

Circulism is a technique that many artists use in attaining a realistic skin texture in drawing. People's faces are not perfect and should not be rendered so. Circlism is basically drawing very tiny overlapping and intertwining circles. The circles do not have to be perfect to achieve this effect. Figure 1 simply illustrates circles that are overlapping and intertwining. Of coarse the circles do not need to be this perfect on a drawing, just an example. In figure 2, I did a quick example of how circulism will look when applied to a drawing. I laid down some 3B graphite and blended in a circular motion with a blending stump. The circulism technique may also be used without blending, depends on your preference.

Source:  http://www.dueysdrawings.com/circulism_technique.html