SPF Explained

SPF Explained

With the inclusion of SPF in more and more beauty products, we’re left wondering: how does SPF actually work? When should we wear it? And what’s the best way to get maximum protection? 

We asked Senior Scientific Advisor at L’Oréal, Atoshi George, to unpack some of the science around SPF and what it can do for our skin. 

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How does SPF work?

SPF stands for sun protection factor and it’s measured in a very specific way to make it consistent across the industry. The SPF given to a product is a way of understanding how much protection it can offer. SPF products work in a number of ways: some use particles which reflect the UV rays away from the skin and others use ones which absorb the energy.

SPF tests look at the time it takes for skin to turn red under a UV lamp: the longer it takes, the higher the SPF. The number is a ratio, so if your skin takes ten minutes to burn, an application of SPF 10 will mean your skin will begin to burn after around 100 minutes, and with SPF 30 after 300 minutes.

When should I wear SPF? 

SPF should be worn daily, and you should wear enough to achieve the level of protection stated. A sparse covering of makeup will not give the same protection as a proper application of sun cream.

And remember that while products with SPF are highly effective, layering and re-application are essential to maintain protection throughout the day.


What SPF should I use? 

Wearing sunscreen under makeup is often impractical, so for everyday exposure, the ideal choice for your face is a moisturiser with SPF. This has multiple benefits: hydrating and plumping the skin, filling out lines and wrinkles to leave it looking and feeling firmer. It can also help the skin work better by improving its barrier properties, increasing its natural exfoliation potential due to the higher water content in the skin.

Our Revitalift Laser Renew Anti-Ageing Cream SPF 20 contains UVA protection as well as SPF 20, which will help keep your skin protected from the sun’s damaging rays.

Check out our daily SPF skin care routine here.

At what age should I start using an SPF moisturiser?

Using an SPF moisturiser is not limited to an age – protection earlier, when your skin is not yet damaged, is much more effective than trying to fix it later. Once the collagen and fibres in your skin are damaged it’s virtually impossible to reverse.

It’s also worth remembering that even if your skin doesn’t usually burn, it is still susceptible to the damage caused by UVA rays, which affect the integral structure of your skin.

Common SPF myths, busted

Myth: you only need to wear SPF when the sun’s out 

What many people don’t know is that UV rays are always present in daylight, not just when it’s hot or sunny. Wearing SPF on your face where the skin is thinner and more prone to long-term damage is essential to keep your skin protected. 

Myth: if you're already tanned, you won't burn

Your skin can be damaged on a deeper level, even after becoming tanned. It’s worth noting that tanning is your skin's way of showing that it’s under attack, and is releasing melanin to help protect itself. There are many alternative options to give your skin a tanned look but not so many to reverse the damage caused by baking in the sun.

Myth: you can't tan while wearing sunscreen

The SPF you apply affects how long your skin can stay in the sun before it burns – so after applying SPF 10 and waiting 100 minutes, the skin will begin to burn. 

Your ability to tan depends on genetic factors, such as the amount of melanin you have in your skin, as well as the length of time you stay in the sun. Sunscreen only extends the length of sun exposure the skin can endure before burning, and doesn’t necessarily impact how deeply you’ll tan or how long it will take. 

Myth: one application lasts all day

Over the course of a day, one application of SPF, especially if over the top of makeup, will easily be wiped away. Applying a moisturiser with an SPF in it, then reapplying during the day, will keep your skin protected from dusk ‘til dawn. 


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