Sure, you have probably been “just fine” slathering on your sunscreen at the beach. But did you notice big spots that you missed later, or maybe you got sunburned? There is actually a correct way to apply sunscreen, and it will result in better protection for your skin.
How Much Sunscreen Should You Use?
How much product to use when you apply sunscreen really is a result of SPF testing. There is an internationally agreed upon standard of 2 mg sunscreen/cm2 of skin surface area to test for SPF. So, to reach the advertised SPF, you want to apply sunscreen so that you reach that amount of coverage on your skin. The “average adult” needs to apply 30 mL or 1 ounce of sunscreen. That’s the size of a shot glass. That means your bottle of sunscreen should not last you an entire summer!
The 2 mg sunscreen/cm2 of skin standard is especially difficult to obtain for a powder sunscreen. Believe it or not, to get the actual SPF stated for a powder product, you would need to apply 1.2 grams of powder to an average woman’s face. What do most of us apply? 0.085 g, which is about 1/14th the amount needed. By contrast, the average woman needs to apply only 1.5x the amount of lotion she usually applies to get the correct SPF.
Timing of Application
Most of us apply our sunscreen at the beach or pool. Actually, you should be applying at least 30 minutes before sun exposure. This means the perfect time for application is when you’re getting ready to head to the sun! I apply my sunscreen for the pool when I’m putting on my bathing suit. It’s a lot easier to reach every spot when you’re alone in your hotel room and can contort yourself in to strange positions without worrying about how you look.
To help compensate for photo instability you should reapply every 2 hours or after being in the water. That means you reapply everywhere, not just your legs or shoulders.
Using “Active” Sunscreen
Don’t forget that sunscreen has an expiration date. You wouldn’t drink Milk 4 months after its expiration date, would you? No, it would be bad. Check your sunscreen’s date! If its outdated throw it out, it is not going to provide the proper protection. Also be careful how you store your sunscreen. It shouldn’t be exposed to high heat or humidity (like in your car). This will also inactivate your sunscreen before its time. Properly store your sunscreen and throw it out once it hits that expiration date.