Cosmetics have come a long way from the days of thick
creams and pancake powders. Using optically complex
pigments and particles that scatter light, today’s cosmetic
scientists and designers have engineered sophisticated
new products that enhance people’s features rather
than cover up their skin.
osmetic products—foundation, eye shadow, blush, mascara and
lipstick—carry with them the promise of transformation. Every
morning around the world, millions of people open small tubes,
But how do cosmetics create their illusory effects? If you open nearly any
magazine, you’ll find ads for these products featuring slick, pseudo-scientific
language and illustrations that would make most researchers wince. But
the truth is that a tremendous amount of real science—both optics and
chemistry—goes into cosmetic development. Modern makeup is a care-
fully formulated mixture of pigments, minerals, polymers, waxes and/or
water. In recent years, scientists have been creating optically complex
pigment particles designed to enhance the wearer’s own skin rather
than cover it up.
When we look at a woman wearing cosmetics, we see the light
reflected off of her face—but it’s not reflected from a single sur-
face like a mirror. Rather, the impinging light travels through
multiple layers: the makeup, the epidermis (the skin’s outer
layer), the dermis (middle layer) and the underlying subcuta-
neous tissues.
To further complicate matters, many portions of the skin
have their own pigments or colors associated with them. The
epidermis, for example, contains varying levels of the brown
pigment melanin, while the dermis has a reddish hue due to
blood vessels. Collagen, a component of the skin found in the
dermis, tends to yellow as a person ages.
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