Beauty Science: SPF & Sunscreen

The sun is shining and it is beautiful outside.  I love the sun and try to get in as much sun in as possible before the winter comes back.  But of course, sun exposure means sun damage, which means I need to use sun screen.

Sun Damage

In my last Beauty Science blog I discussed antioxidants and Vitamin C’s role in protecting you.  The vitamin C protects us from reactive particles.  Well, sunscreen is along that same line, but instead of protecting us from existing free radicals, it stops more from being created.  When the Sun shines down on us it is pelting us with high energy photons (remember, light is both a particle and a wave).  These photons will sometimes hit the atoms in our body and knock off an electron creating a free radical, which can then damage the skin cells around it.  There are two types of UV rays that cause this damage, UVA and UVB.  The difference between the two is the wavelength of the light.  UVA’s wavelength is longer and penetrates deeper into the skin.  UVA causes premature aging.  UVB has a shorter wavelength and only hits the outer layer of skin.  UVB causes sunburns and tanning.  Both types of UV rays have the potential to cause cancer.

Our body has a natural way to protect us from the sun.  Dark skin pigmentation scatters and absorbs light (hence the skin looks darker).  Therefore, as we expose our body to the sun, our body produces more melanin to darken the skin, creating a tan to protect us. Often this protection is not enough, or is not produced quickly enough, and we require additional protection from sunscreen.

What SPF should I use?

Contrary to popular belief, a higher SPF does not mean that you get more protection from the sun.  SPF, or Sun Protection Factor, tells you how long you will be protected from the sun’s UVB rays.  The number is a factor that tells you how much longer you can stay in the sun without being burned compared to no sunscreen at all.  So if you are fair and burn after 10 minutes of exposure to sun, than applying an SPF of 15 means that it will take 150 minutes for you to burn.  Conversely, a SPF of 30 would last for 300 minutes.  It is tempting to think then that high SPF means that we can go longer with just one application, after all, that is the point of the number system.  But alas no.  Sunscreen comes off the skin over time, so you do have to reapply it for continued protection.  Thus, it is recommended that you reapply your sunscreen every two hours regardless of the SPF level.  Therefore, there is little benefit of using sunscreens with SPF that provide protection longer than two hours.  They tend to be more expensive and can irritate sensitive skin.

How does Sunscreen work?

There are two types of sunscreens.  Those that reflect UV light and those that absorb UV light.  Sunscreens that reflect light are made of Zinc Oxide or Titanium dioxide.  When you think of the lifeguard with white nose, that would be a reflective sunscreen.  Nowadays, the Zinc Oxide or Titanium dioxide particles have been made smaller and formulas that don’t make you look white exist.  They reflect a wide range of UV light and will protect you from UVA and UVB.  They are very safe and inert and tend to be the primary agent in children’s sunscreen lotions.

The second type of sunscreen works by absorbing the UV light.  The early forms of these sunscreens only absorbed UVB light and not UVA light.  However, now chemicals that can block UVA light exist as well.  SPF only refers to how long the sunscreen can block UVB light though, so make sure you choose a Sunscreen that specifies that it is full spectrum, which means it will block UVA as well.

What is flash back?

If you watch a lot of fashion videos, you will hear vloggers caution against using SPF because you will get flashback.  The thought is that because sun protectors reflect light, the light will bounce back to the camera.  And there are a ton of pictures of celebrities that look like they have white powder all over their face thanks to flash back.  As I mentioned before, some sun protectors reflect light, but others absorb light, so if your makeup uses Zinc oxide or Titanium dioxide, you might get flash back.  But the story doesn’t end there.  It is not only SPF makeup that can cause it, it can also be caused by powders.  So it is hard to tell who is the exact culprit.  But here are some resources:

A blog that tests the flash back of a lot of SPF foundations

Video on tips on how to deal with flash back:


It is hard to come to any other conclusion than that YES you should use sunscreen.  Despite this, I am resistant to using sunscreen because when I am outside for a long time, it is generally because I am doing some sort of sports activity that is going to make me sweat.  I have found that sunscreen comes off when i sweat and somehow always manages to stream directly into my eyes, or so it seems.  Because I tend to tan and do not burn unless I am exposed for a prolonged period of time, I generally skip the sunscreen.  Obviously this is not ideal because I am still subject to damage.  As i have gotten older, i have noticed my skin is sun damaged.  Thus, i am trying to stop this bad habit.

Luckily, i have found a great sunscreen that I have had good luck with.  This past weekend I tried Banana Boat Sport while doing hill climbs on my road bike in +30°C. The sunscreen is SPF 30, offers both UVA and UVB protection, and is “Ultra sweatproof”.  I am glad to report that I was impressed with this sunscreen.  It absorbed well (with a lot of rubbing it in) and stayed put.  I got NO sunscreen in my eyes!  Granted, I only lasted for an hour in the heat, but my partner went for around 3 sweaty hours and he reported similar experiences.

If you have had good experiences with sunscreens, comment below.

If you notice any errors in this post, please contact me so I can correct the error.

Edit July 30th, 2015:

Lisa Eldridge just made an excellent video on sunscreen:

image from: Kristina Alexanderson