
Tragic Alley, 2006, by Fred Hatt
Alley is an actress and a great professional artist’s model with strawberry blonde hair and alabaster skin. In trying to capture the impression of brightness when drawing Alley, I use a lot of white crayon. But clearly there are other color tendencies that I can see – pinks and yellows and pale blues. These are not so much the surface color of the skin, which is pretty near white, but result from the translucency and reflectiveness of the skin. Light penetrates below the surface, where blood flow gives it a reddish tone. Other colors reflect off the satiny surface of the skin, picking up the colors of surrounding objects and light sources. The slight yellowness is probably imparted by whatever low level of pigment (melanin) is there.

Alley, 2009, by Fred Hatt
There are basically three types of melanin, the pigment that causes the spectrum of human skin tones and hair colors. As the relative levels of red, green and blue in a computer monitor produce a wide range of hues, so the varying concentration of pigments create complexions we might describe as ivory, ruddy, olive, mahogany, butterscotch, cafe au lait, brown, and black, and all the hair colors from platinum blond and ginger through jet black. The three pigments are black eumelanin, brown eumelanin, and pheomelanin, which is reddish. Most hair-covered mammals have relatively little skin pigmentation, so scientists believe dark skin evolved as a protection against sun exposure and was later lost in populations that migrated out of the tropical regions.
The redness of blood in capillaries shows through the skin, as we can observe in flushing and blushing. A model holding a standing pose for a long time may show a noticeably redder tone in the legs and feet, and sometimes in the hands if they’re hanging down, as gravity causes blood to pool in the lower areas. In some light-skinned people you can see veins through the skin, especially around breasts, neck, shoulders and inner arms. Veins have a bluish appearance, even though venous blood is deep red, not blue. This phenomenon apparently results from the fact that the veins themselves absorb more light than other structures underlying the skin. As most of the light that reflects back through the skin is reddish, the relativistic nature of color perception causes the impression of blue in these less reflective areas.

Jessi, 2009, by Fred Hatt
Of course sun exposure causes an increase of pigment in the skin. The pinkness of the skin immediately following a sunburn is, as far as I understand, a result of inflammation in the capillaries, and so is imparted by blood, not pigment. The increase of pigment we know as tanning follows more slowly.

Beth Sunburned, 2003, by Fred Hatt
Veins don’t show through very dark skin, but dark skin still has the qualities of translucency and reflective sheen. Backlight that glances off the surface of dark skin can have a particularly vivid effect, as shown in this drawing where cool-toned window light comes from behind the model, Ken.

Kenneth, 2009, by Fred Hatt
To my eye, dark skin often seems to take on a reddish tone in the shadows, and a golden tone in the highlights. I think this has to do with the way the light penetrates the surface and reflects back. African and African-American skin tones have an even broader range of hues than European or Asian types. The model for the drawing below has a very dark complexion. I was taken with the range of colors of light I could see in her skin, reflecting off the sheen, glancing through the edges, bouncing into the shadows.

Aimi, 2009, by Fred Hatt
I’m not medically trained, so it’s possible I have gotten some of my physiological facts wrong. If you have better knowledge, leave a comment.
All drawings in this post are Caran d’Ache aquarelle crayon on gray Fabriano paper, 70 cm x 50 cm.