SPF Education | bluemercury

Be a know-it-all
when it comes to sun safety

It's smart to protect yourself from the sun, but not all sunscreens are created equal. Our beauty experts explain all the sun-related lingo and what it means for the health of your skin.

Words to Know


Short for Ultraviolet A, these rays penetrate deep into the skin and are the largest cause of premature skin aging and wrinkles--also known as photoaging. They can also contribute to skin cancer as well as a suppressed immune system.


Short for Ultraviolet B, these rays are the chief cause of skin reddening and sunburn and tend to damage mainly the skin's surface. They are the most significant contributing factor to skin cancer.

Tip: Applying full-body sun protection year round is crucial because of the long-term effects of these damaging rays.


Short for sun protection factor, this abbreviation followed by a number indicates how many times longer it will take for sunscreen-protected skin to burn than unprotected skin. For example, an SPF 15 sunscreen means it will take 15 times longer to burn than if you weren't wearing any sun protection.

Tip: An SPF factor of 15 is the minimum needed to prevent skin damage from UVB.

Broad Spectrum

Broad Spectrum is an all-protective form of sunblock which protects against both UVA and UVB rays. The sun protection factor, or SPF number, refers only to UVB protection.

Tip: Wearing broad-spectrum protection every day, even on cloudy days or days you’ll spend inside, is the key to keeping skin healthy and avoiding premature aging.

Physical Sunscreen

Physical sunscreens create an impenetrable shield against the sun's rays and are made with zinc oxide or titanium dioxide. The particles in these ingredients sit on top of the skin and reflect all UV rays.

Tip: These tend to be less irritating to the skin than chemical sunscreens. This is particularly beneficial for kids and individuals who have sensitive skin.

Chemical Sunscreen

Chemical sunscreens contain organic, carbon-based compounds that create a chemical reaction to convert UV rays into heat, which is then released from the skin without burning.

Tip: Chemical sunscreens can take up to twenty minutes to absorb into the skin, so make sure to give yourself the appropriate amount of time to let it soak in.

Water Resistance

In the USA, the FDA only allows two claims, Water Resistant (40 min) or Water Resistant (80 min). These retain their stated SPF value for the specified time, in water or while sweating.

Tip: Be vigilant about reapplying approximately every two hours or more frequently if you're sweating or in water, even if the product claims to protect for a longer amount of time.

Expert Tip:
Technically, any tanning is damaging to the skin and should be avoided at all costs. But, if you do choose to be in the sun, wear adequate protection!

7 Most Common Skin-Protection Mistakes

  1. Not using enough product. To cover your entire body with sunscreen, it takes about one ounce or the size of a shot glass. Most people will under apply by about 50%.
  2. Forgetting to reapply. Sunscreen should be reapplied throughout the day because the active ingredients lose their effectiveness over time.
  3. Not rubbing in sprays. Spray formulas are quick and easy to apply but you are more likely to miss spots and end up with uneven coverage. For your best protection, continuously spray for about five seconds on a particular area and then rub in thoroughly.
  4. Not applying when you’re going to be inside. Even though you may feel protected, UV rays still enter through windows, whether you're in your home or riding in a car.
  5. Thinking clothing will protect you. Even if you believe you're covered, the sun's rays can go through clothing, and you can still get burned.
  6. Using expired sunscreen. The expiration dates printed on your sunscreen aren't just for show. From the moment you open your sunscreen, the clock starts ticking. Exposing it to direct sunlight can decrease it's effectiveness, shortening its lifespan even further.
  7. Repeatedly missing the same spots. The most common areas missed by sunscreen are scalps, ears, eyelids, lips and the tops of your feet. Try using sprays for your scalp and stick format for ears, eyelids and lips

Expert Tip: Limit sun exposure when it's at its highest point in the sky, around 10 a.m. to 3 p.m. Cover up with a hat, sunglasses, lightweight clothing and of course, sunscreen!

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