I found this video again, and decided to 'keep' it here this time, and not lose it again.
It would seem simple enough - what's demonstrated in the video - but really, it isn't. To fill in the shadows, you'd need to look at your piece, and decide what's on top, and what's underneath. Easier said than done.
Putting in the shadows is a necessary step, I feel. It will lend depth to the finished piece, and keep it from looking flat.
Just look at the astounding kettle she's done! Simply beautiful work.
Can't wait to try this out!
Or, watch the extended version, with explanation of what she's doing, and why: