dealing with tanned parts of models

Dan Gheno on how the tanned portions of a nude model seem to stand out and push forward:

"Pay close attention to the local value differences of each individual body part. Arms, legs, necks, and faces regularly get more exposure to the sun and appear darker than the rest of the overall figure. If you see this in your model as you draw, don’t ignore it; any foreshortening in the limbs will become magnified when you draw a slightly darker arm or leg silhouetted against a lighter torso. Even a slightly darker neck will seem to push forward as a mass when viewed against a slightly lighter shoulder mass. But remember, this effect is subtle, and as always, primarily trust your eye.

"I often encourage my students to study individual, isolated body parts to help them better understand human anatomy and amass a working vocabulary of figure forms that will aid them in seeing detail more quickly and precisely. As constantly happens when you draw something out of context, your sense of foreshortening becomes hampered when drawing a leg or an arm detached from the torso. Don’t let yourself unconsciously correct the foreshortened proportions while drawing a bent limb. If the upper arm looks a lot smaller than the lower arm, draw it that way, and it will have more life and dimension."