How Neutrogena® Formulates Zinc Oxide Sunscreens
Neutrogena® has been formulating mineral sunscreens for over 25 years and was one of the first companies to include a zinc oxide concentration of higher than 20% in its mineral sunscreen lotion. It takes 9 months to a year for Neutrogena® to formulate a new sunscreen. Here’s a peek into that process.
Zinc oxide is an inorganic sunscreen filter, “which means that the actual zinc oxide molecule does not contain carbon,” explains Dr. Bianchini. A chemical sunscreen filter that is labeled “organic” means that it contains carbon atoms —not that it’s any more likely to be found at your local farmer’s market. “When we talk about organic versus inorganic sun filters, we’re talking about them from the chemical definition of the sun filter.”
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Neutrogena® sunscreen lotions that contain zinc oxide are emulsions — a mixture of two liquid phases, usually oil and water. Usually, when oil and water are mixed, they don’t like to stay together. However, including ingredients like emulsifiers, which have both water-loving (hydrophilic) and oil-loving (hydrophobic) properties, hold the two phases of the emulsion together. The zinc oxide is dispersed within the oil phase, and then both the oil phase and the water phase are homogenized to form the final emulsion, or sunscreen lotion. Neutrogena® sunscreen sticks are anhydrous, which means there’s no water in the formula. The zinc oxide is dispersed in oils, and waxes are added to give the formula its solid structure.
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Before a new formula enters the market, it undergoes rigorous testing — after all, it can’t run into your eyes, sting or clog pores. And at Neutrogena®, when formulas are being developed they are tested under stress conditions such as high heat and freeze/thaw cycles to ensure they are stable under these extreme conditions “All of our recreational sunscreens provide water resistance, which is tested through an FDA test method where the subjects are immersed in water for 40 or 80 minutes and then the SPF value is determined. This ensures that sunscreen is efficacious for using in a recreational setting while swimming or sweating” says Dr. Bianchini.
Neutrogena® may test hundreds of prototype formulas in the lab before landing on the perfect one for final development.
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