Ambient Occlusion layer

I decided the light was going to be coming from the top right. I made a new layer above the Silhouette layer and below the Ink sketch. I set this to ‘Multiply’ as a blend mode and also set it to ‘Clipping Mask’, so that it used the silhouette to constrain any painting into the shape from the lower layer. I then painted in dark areas where I wanted occluded shadows – mostly in the lower areas and in cracks.