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The Mysteries of R&D, Part I
By: Art Rich, PhD
Posted: June 22, 2010, from the July 2010 issue of GCI Magazine.
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One further note: The “cracked” term used for emulsions simply means that the cream or lotion has separated into distinct layers. It is no longer homogeneous.
Components of Skin Care Products
Now, here are a few types of materials that can be delivered through emulsion systems. Emollients: These are added to provide a skin-softening effect. Chemically, they are esters that can be modified to vary the feel on the skin. Those that have a “dry” feel have virtually no perceptible feel on the skin. Those with a “wet” or “oily” feel leave a noticeable residual on the skin.
Exfoliants: These are included in skin care formulas to remove the uppermost layer of dead cells. They provide for the newer “more alive” cells to be at the surface. They also impart a glow to the skin.
Exfoliation can be done in either of two ways: mechanical and chemical. The mechanical method physically abrades away dead cells. Ingredients for this purpose include ground walnut shells, beads of jojoba wax (which can also melt onto the skin to provide emolliency) and plastic spheres of polyethylene or nylon. Chemical exfoliants perform by reacting with the dead, upper layer skin cells. This causes the cells to become unglued and slough off. Ingredients for this purpose include: alpha-hydroxy acids (AHAs) such as glycolic acid and fruit acids. Beta-hydroxy acids (BHAs) are also chemical exfoliants and include salicylic acid and willow bark extract (which contains salicylic acid), and these are very effective. Note, when AHAs are included in a formula, there needs to be an advisory label cautioning about exposure to the sun. In addition, there needs to be an effective sunscreen present in the formula.
Sunscreens protect the skin from the harmful effects of ultraviolet (UV) rays. There are two UV ranges of wavelengths that cause problems: UVB causes stimulation of melanin to induce tanning, but also causes burning. UVA penetrates more deeply into skin tissues, and these rays are involved in the destruction of DNA and breakdown of cell structure via free radical release, causing the appearance of premature aging and wrinkling.