Working on Red Cone, the Shadow

I've been back to work in the studio after my nyc trip, moving down the painting to the center part of the cone. I added several layers of color to all unfinished parts of the painting, in a fluid manner, just to get a less transparent surface. These gestural, underpainted layers add to the richness of the final layers. I concentrated on finishing the curved purplish shadow running across the form. The challenge here is to get a sense of light within shadow, to have a movement of color and value that articulates the form. We often tend to think of shadows as devoid of light, but if we look at them in isolation, blocking out the light part of the form (I often had my students do this by making a small window with their hands), we can see that they are full of color.