OK, here is the completed "Crab in Space" underpainting. I used only two colors (cobalt blue and raw umber) to draw the crab and establish some color in the background. At this stage, I look to see if I'm happy with the conversation and lights/darks. This process gets me more familiar with the lines of the shapes and how they will interplay with each other. I'm still not sure what I'll do with the background. I'll let this dry and then start with the background to see what might happen next:
