Life Drawing week 4

Should have posted this ages ago. This was a particularly enjoyable week for me. Tried a technique that would influence the next 4 weeks. You can see it develop over the first 3 drawings here.

  These 2 are where I inverted the images in photoshop. I unfortunately love doing this.

 Added the dark under the arms later - kinda think it works in the thumbnail, not so sure once it's at full size.