Home Skin Care We scream for sunscreen!

We scream for sunscreen!

by Louisa Crook

Serums, balms, ointments, treatments, masks, actives; the list goes on when it comes to all the wonderful ways you can improve the look, feel and appearance of your skin. But it’s all for nothing if you don’t wear SPF all day, every day! There’s a reason every dermatologist and esthetician out there pushes this part of any skincare routine the hardest. Let’s break it down.


While you always want to be wearing a broad spectrum SPF, it is worth knowing the difference between UVA and UVB. UVA is what ages your skin and UVB is what burns it. We want to avoid both of those things. Sunscreen isn’t only about slowing the signs of aging – the most important function of SPF is preventing skin cancers from occurring. So, with all that in mind, always opt for a “broad” or “full” spectrum sunscreen.

Sun Protection Factor ratings

In case you didn’t already know, “SPF” stands for Sun Protection Factor. This refers to the length of time you will be protected for when in the sun while wearing your sunscreen. The basic formula for figuring out the SPF is the number of seconds it takes a patch of skin to redden when there is SPF applied versus no SPF applied. So, for example, if it took 300 seconds for the skin to redden with a sunscreen applied and 10 seconds to redden without it, it would be a factor 30 (300 divided by 10). This essentially dictates how often you will need to reapply the sunscreen when out in sunlight. It is generally believed that SPF needs to be reapplied every two hours when out in direct sunlight (more often if you’re swimming or sweating) and that you should always select an SPF of 30 and above.

What about when you’re indoors? No SPF required, right? Wrong. Windows are not sunblock and plenty gets through them. So apply sunscreen when indoors as well, but you can forego the reapplication as long as you apply a good layer of SPF to begin with. Speaking of a good layer of SPF…

Proper application of SPF

The Sun Protection Factor rating is based on proper application of sunscreen. This means if you’re not applying enough, you simply won’t get full protection against the sun’s harmful rays. This means at least half a teaspoon of SPF to cover your face and neck (don’t forget the ears!). No dabbing it on like highlighter (thank you very much, Mrs. Paltrow). Furthermore, it should always be the last step of your skincare routine so that the layer does not get disrupted by rubbing in other products. Think of sunscreen like a thin but complete barrier on top of your skin (or just inside it, as with chemical sunscreen.

Chemical sunscreen versus mineral sunscreen

Another consideration when choosing sunscreen is whether you go for a chemical or mineral (sometimes called physical) sunscreen. Both of these protect from the sun’s damaging rays but they use different mechanisms. So what’s the difference?

Mineral sunscreen

With active ingredients such as titanium dioxide or zinc dioxide (often both), mineral sunscreens block UV rays at the surface level. They sit atop the skin and form a physical block that reflects UV ray away from the skin. Think of mineral sunscreen like lots of tiny little mirrors all over your skin. Your sun protection is instant with mineral sunscreens. This means, in order to get the most of out of a mineral SPF product, you have to apply it liberally (remember that half teaspoon minimum we talked about) and be careful about reapplying. It sits on the surface of the skin so rubbing or sweating it off is easy to do. Physical sunscreen also tends to be the one that creates what is referred to as a ‘white cast’ more so than chemical sunscreen.

Chemical sunscreen

Chemical sunscreens work very differently to mineral or physical sunscreens. These SPF products are absorbed by your skin, rather than sit on top of it. They then absorb UV rays, turn them into heat and then release that heat from the skin.

As you might expect, chemical sunscreen takes longer to work than the instant efficacy of mineral sunscreen (so be sure to apply your chemical sunscreen at least 20 minutes before your sun exposure). Chemical SPF also allows some UVA exposure to occur due to the fact that the sun’s rays penetrate the skin. Further to this, those prone to rosacea and hyperpigmentation can find chemical sunscreens problematic due to the heat-releasing function of them. Those with acne-prone skin can also find that chemical sunscreens exacerbate their issues because chemical sunscreens tend to be more likely to clog pores. Chemical SPFs can also contain some controversial ingredients such as oxybenzone.

So then why, you may ask, would someone opt for chemical over mineral sunscreen? Well, there are pros! Chemical sunscreen is thinner and easier to apply. It absorbs deeper into the skin, and less is required for protection. This means there is more often than not, no white cast issue. Further to this, if you’re going to be out swimming or sweating a lot, rather than constantly reapplying mineral sunscreen, a chemical one might be much more convenient, though it still needs to be reapplied a minimum of every two hours.

It can take some time to find the right sunscreen for your skin but the bottom line is that any sunscreen is better than no sunscreen, so don’t skip this most important skincare step!

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