Human skin is made up of reds, yellows, and blues — the primary colors. When you mix the primary colors together in the right proportions, you get a rich, natural brown. Depending on the darkness of the skin, you may also use titanium white to bring out the contours of the face and the highlights on the skin. So, now the only issue is which of the reds, yellows, and blues to use:
- Yellows: Yellow ochre is a wonderful old color that's been used as an art pigment since the beginning of human history. You can also use raw umber or burnt umber for dark skin.
- Reds: Cadmium red light is perfect for a florid complexion, and alizarin crimson works well for dark skin tones. Examine the reds that you see in the lips; try to determine whether you see orange-reds or red-violets and then experiment!
- Blues: Ultramarine blue is a warm blue that works well to dull the brilliance of the red and yellow. When you mix in the blue, the result is a natural-looking skin color.
- Titanium white: This is the perfect white to use. The old masters used lead white, but you should avoid it because of its toxicity.
For darker skin tones, start the same way, checking your orange against the skin tone that you're painting to see whether it leans toward red or yellow. Then, rather than adding white at this point, start adding ultramarine blue until you have a color near the value of the skin tone that you're looking for. Finally, add white to lighten the color and make it look more natural. You can also experiment with using raw umber and burnt umber in your mixtures.
The main mistake that people make when working with darker skin tones is relying solely on white to lighten the color. White may make the color too dull and ashen to look natural for many people. Keep a stock of your orange set aside to brighten the color if it becomes too dull as you lighten it.