We’re back again, and this week on the blog we’re talking about how the hell sunscreen actually works and why it’s so important to reapply to avoid sun damage!

There are a lot of sunscreen myths floating about on the internet, which is why it’s important to find trustworthy sources and take everything with a grain of salt (except ours, because MOTHER knows best). In this week’s instalment of bloggin’, we wanted to dive into the world of SPF (that’s sun protection factor) and unearth some facts you may not know about what the number on the bottle really means. Allow us.

When physical sunscreen is applied, it acts as a barrier screen type-thing between your precious, precious skin cells and the harsh UV rays of the sun (which is what damages skin cells and can cause cancer and premature aging). This is where SPF swoops in. SPF is essentially the measure of how many UV rays are able to muscle their way through the sunscreen barrier and do the damage. The higher the SPF rating, the less UV rays can wriggle in.

When we look at the difference between SPF 15, 30 and 50, the margin isn’t actually as vast as it may sound. An SPF 30 allows approximately 3% of UV rays into the skin, whereas SPF 50 allows 2%. If we reverse this, SPF 30 has you 97% covered from UV rays, and SPF 50 gets you to 98%. SPF 15 sits at roughly 93%.

If we think of this in the context of time, SPF serves as a guide on how long one can stay in direct sunlight before the skin starts to burn. If you have a rough idea of how long you can be exposed to the sun before turning into a lobster, you can multiply that number of minutes by the SPF rating that you are using. That is how long your sun protection will last sans swimming or sweating. For example, if you burn after 20 minutes of unprotected sun exposure and you are wearing SPF 30 you will get 10 hours of sun protection (20 minutes x 30 = 600 minutes = 10 hours)

In a perfect world, you could extend your stay in the sun for 10 hours and only rely on sunscreen. Unfortunately, we’re still working on the perfect world thing, and if you sit in the sun for 10 hours (please don’t) with only sunscreen protecting you, you will very likely still burn.

So, there you go! Was that as mind-numbing as you’d prepared for? At the end of the day, whatever you can whack on is better than nothing, just remember to reapply diligently so those pesky UV rays don’t get past the bouncers.

Image: @cameron_hammond