Practicing Definition with Negative Space

Using this simple image, this is a good time work with defining the flower in negative space. 

Micron pen on 500 series Strathmore mixed media paper.  Click on image to enlarge. 

The shapes of the petals in the sketch above are defined by the crosshatching around them.  I enjoy creating these types of images and will need to be deliberate if I am going to incorporate this type of negative space into a full scale work. 

Below is a close up sketch, and not only uses negative space but the idea of a window frame restricting a portion of the view.  The entire sketch is just two petals; this is not a cropped sketch.

Micron pen on 500 series Strathmore mixed media paper, white.  Click on image to enlarge.