Bird bones process...

I found these bird bones a good few months ago, but I've only just gotten round to drawing them. Bones in general fascinate me (as is evidenced from previous posts) but I was particularly interested in the delicate look of these. My support is Strathmore toned grey paper, and I begun with a light graphite sketch. This is simply the basic shape of the subject, with no emphasis on detail or tone yet. Once I've got the basic construction in place and I'm happy with the composition I'll block in the basic shadow shapes. This isn't taken to any degree of finish, just a generalised approximation of shadow placement. I did this shadow block-in using graphite powder applied with a small filbert brush. Now that the drawing is a little less flat, I build up layers of shadow/tone gradually, in multiple layers. I tend to work from the darkest values into the middle tones and only in the last layer of rendering will I add the white charcoal highlights. They're like a bonus for yourself at the end of the process that brings it all together and adds that extra bit of depth and form.