By Nicki Zevola, Pennsylvania, Skincare Expert
Nicki Zevola is a beauty expert and the founder of FutureDerm.com, where she provides clear, well-researched information about beauty+skincare, fashion+style, nutrition+fitness, and personal development from a different perspective from most in the blogosphere. Named one of the top beauty bloggers since 2009, Nicki is also a medical student (M.D.) with an estimated graduation date of May 2013. Continue reading her full bio…
5 Surprising Skincare Facts You Didn’t Know (Until Now!)
1. Mixing certain skin care ingredients inactivates them.
Even if you hated science classes, you have to keep in mind that skin care is the product of somewhat advanced chemistry, subject to pH imbalance, unexpected reactions, and the like. For instance, many cosmetic chemists do not recommend using products with alpha hydroxy acids, like glycolic acid, and retinol together. This is because retinol is most active at a pH of 5.5-6.0 (Journal of Investigative Dermatology), while glycolic acid has an optimized pH at 3.83 (Cosmetic Dermatology). Another problem is using a heavier skin care product under a lighter one. High concentrations of certain occlusive agents like petrolatum and mineral oil prevent the ingredients in the lighter serum from reaching your skin as effectively. Most dermatologists thereby recommend applying the lighter product first.
2. You should never apply self-tanner before going out into the sun, unless you use a sunscreen first.
Most self-tanners work by using dihydroxyacetone (DHA) as the main ingredient. According to a 2007 study published in Germany, DHA causes the skin to release 180% more free radicals once exposed to the sun. Therefore sun protection is extremely important when you have used self-tanners containing DHA within the past 24 hours.
3. There is no such thing as 100% SPF protection from a sunscreen.
According to dermatologist Dr. Rachel Herschenfeld, M.D., the percentage of protection you get is 100 – (1/SPF number)*100. I know that looks complicated, but let’s take SPF 30 for example:
Percentage of protection = 100 – (1/SPF number)*100
Percentage of protection = 100 – (1/30)*100 = 100 – 3.3
Percentage of protection = 96.6
Using that same principle, SPF 50 provides only 98% protection, and SPF 100 provides 99.9%! Keep in mind this is the amount of protection provided when you apply a whole shot-glass full of sunscreen for your entire body and reapply religiously every 2-3 hours. As such, it’s safe to say there is no such thing as 100% sun protection from a sunscreen.