Self Tanning - Cosmetic Formulation Basics
Self tanning products are designed for people who want to darken the color of their skin without risking the negative health effects of UV exposure. Technology improvements in the purification of the main active ingredient and better awareness of the dangers of excessive UV exposure has led to an increase in the sales of these types of formulations
What self tanning formulas do
Self tanners are active cosmetic formulations that stain the outer layers of the skin and give it a more yellow/brown/orangish hue. They can be applied as a lotion or spritz and will slowly change skin color as the dye reacts with skin protein.
How do self tanning products work
The primary active ingredient that makes self-tanners work is Dihydroxyacetone (DHA). This is a white, crystalline powder whose skin staining effect was first discovered in the 1950’s.
DHA is a 3-carbon sugar that naturally forms a dimer. When heated in a solvent, the molecule can revert to a monomer which is more effective. The reaction that causes skin browning is the Maillard reaction in which the hydroxyl group on the DHA reacts with skin amino acids & proteins. It typically requires about an hour for the color change to be noticed.
The delivery of DHA is typically in the form of an oil-in-water emulsion similar to a skin lotion. Since the palms will stain darkest, consumers have to wash it off or wear gloves for application to prevent unnatural looking browning on the hands.
The color will wear off as the outer layers of the skin are naturally removed via exfoliation.
We should note that while there are some spray-on self tanning products, this use has not been approved by the FDA.
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