Sunscreen application how-to
We all know that daily use of at least 30+ SPF is the most important factor to prevent photoageing. But it’s a compromise - depending on which formulation you choose, high factor sunscreens are often gluggy, don’t play well with makeup and can make us look ghostly. Many of us search in vain for the holy grail of SPF formulation: high SPF coverage + cosmetically elegant formulation. Too often however, there is a disparity between the recommended use of sunscreen (high SPF rating, correct amount used, reapplication times) and what we actually do in practice.
Here Qr8 investigates (a) why you should even bother wearing SPF, and (b) the effect of different SPF formulations and application methods on coverage.
(A) why wear sunscreen at all?
A 2018 study conducted by Monash University suggested that Australian women look 20+ years older than women in other parts of the world (fair-skinned Asian and Caucasian Australian women were compared with those living in Canada, the UK and the USA). In this study 1472 women aged 18-75 years (average, late 40s), self-assessed their features against a rating scale depicting degrees of severity of facial lines and volume-related features like tear troughs and naso-labial folds (the two skin folds that run from the nose to the corner of the mouth). 30% or more of Australian women who reported moderate or severe ageing for all features were aged 30-59 years versus 40-69 years in US women. This difference was attributed to high levels of UV exposure in Australia.
There were some methodology and statistical issues with this study: only photo-ageing was considered, not other contributing factors (although figures were adjusted for age, race and smoking status), severity was self-reported (so biased) and the statistical analysis wasn’t compelling (not a huge difference between results from women of different countries, and these might have been different if a cutoff other than the 30% had been chosen). Regardless, it highlights the issue that multiple studies associate photoageing, regardless of other lifestyle variables that contribute to intrinsic ageing, with increased degenerative changes in dermal tissue that lead to skin laxity, wrinkles and pigmentation.
Sunscreen and photoageing
So what role does sunscreen play in photoageing? Multiple studies show that sunscreen reduces the biological processes or markers associated with photoageing. But one trial in particular sums it up (Darlington S, Williams G, et al. 2003): daily sunscreen use over 4.5 years in 1621 adults aged 25-74 years in Qld, Australia showed that skin ageing was 24% less in the daily sunscreen group than in the discretionary sunscreen group (those that only wore it occasionally).
We know that UV radiation (UV-R) leads to a breakdown of collagen in the matrix between skin cells and a shutdown of new collagen synthesis. So, applying a broad-spectrum sunscreen with an SPF30 or higher helps prevent photoageing via collagen/elastin breakdown. Sunscreen should be applied every day when the UV index is 3 or higher (there’s an app for that!), even when it’s raining or cold outside. Remember, SPF is not a suit of armour; staying out of the sun and wearing protective clothing is always a better option.
In short, if you are spending time and money looking after your skin, and NOT using sun protection, then you are wasting your hard earned resources. It the least sexy but most important addition to all other interventions against skin ageing.
Numerous studies show a disparity between recommended use of sunscreen and practice. We usually apply 20-50% less sunscreen than the dose (2mg/cm2 ) used in SPF testing, hence we are getting much less than the SPF rating advertised on the container.
2mg/cm2 equates to 1/4 teaspoon just for the face (so you will need more to cover your ears), and another 1/4 teaspoon for the neck and chest. This needs to be spread evenly around the face and allowed to settle before adding makeup over the top. Some people dot it around the face first, then rub it in to ensure even coverage. If you’re unsure what 1/4 teaspoon looks like, use a measuring spoon so you know you’re getting enough.
(B) effect of different Sunscreen formulations on coverage
In our hunt for the holy grail of sunscreen formulation, we often turn to non-dedicated sunscreens (tinted moisturisers, makeup with SPF, powders) and mix sunscreen and makeup together. But what effect do these practices have on sunscreen coverage (evenness of coverage, areas of skin left unintentionally omitted, dilution of sunscreen, etc), and hence ineffective blockage of UV rays? So we decided to investigate…
Eds note: the investigations performed for this study all used zinc and titanium-oxide (inorganic, mineral) sunscreen agents to compare apples with apples. 1/4 tsp of sunscreen was applied each time, using a measuring spoon to ensure a consistent amount. Sunscreen was removed between each application by cleansing twice with cleansing oil and a microfibre cloth. Skin was moisturised with a plain emollient moisturiser and left for 5 minutes prior to applying each sunscreen. A UV lamp (365nm wavelength) was used to assess SPF coverage. It’s well known that I’m a sunscreen nazi, so I applied sunscreen in my usual way, making sure to cover all areas of the face.
bare face vs full face dedicated spf30+ mineral Sunscreen
Let’s kick things off by showing you the ideal situation (and my face in all it’s UV-light glory - in other news I will be upping my eye cream game as those dark undereyes are apparently dehydration!):
You can see the sunscreen blocks the path of the UV light so you can’t see the skin underneath. I’m pretty impressed with my application skills (only a few missed bits!). I used a dedicated sunscreen designed for face application, meaning it’s not a tinted moisturiser, or CC cream, nor is it a sports/body sunscreen (so it was relatively cosmetically elegant for a dedicated sunscreen).
dedicated SPF30+ sunscreen vs tinted moisturiser spf30+
Ok, I’m preaching to the converted, but you already know that a dedicated high-factor sunscreen is the best option for UV-R protection. But it feels awful on the skin. So why not opt for a very popular brand of tinted moisturiser with mineral SPF30+? Let’s take a look…
As they say, a picture paints a thousand words. I applied 1/4 teaspoon to my face, about what I would normally apply in either moisturiser or foundation. This gave a lovely light ‘makeup’ coverage, but clearly not a great SPF coverage. 1/4 teaspoon looks like this:
Then I decided to up the ante - what if I did multiple coats of tinted moisturiser? Would this give me the same coverage as a dedicated sunscreen? So I applied 3 coats (1/4 teaspoon each) and waited 5 minutes between each coat before applying the next. Here’s what this looked like under the UV lamp:
After 3 applications, I had so much tinted moisturiser on my face that I couldn’t rub any more in, and it looked streaky, cakey and felt heavy (so not something anyone would ever do). Even after 3 coats, the UV blockage doesn’t come close to 1 coat of dedicated sunscreen.
SPF15+ mineral powder
This is a very popular mineral powder foundation, that is often used as a stand-alone sunscreen. Here’s what kind of UV blockage you can expect from this:
I’d save this one for over the top of another SPF product but remember that SPF isn’t additive - if you use an SPF15 powder over the top of an SPF15 moisturiser or sunscreen, you can only ever get SPF15. And given that most people don’t apply the correct amount to start with, you may only end up with a good coverage of SPF15 (the Cancer Council recommends SPF30+ as a minimum).
sunscreen and foundation
Here’s some good news: I tried using the SPF30+ dedicated sunscreen then going in straight away with a foundation. And it didn’t make any difference to the coverage (although the foundation does contain titanium dioxide, so I think I just doubled up on my SPF application)! But look what happens when I use a damp beauty blender to apply foundation (I dabbed the foundation on gently with my fingers, then blended with the sponge) - and this was after leaving the sunscreen to settle for 10 minutes.
And finally – reapplying sunscreen after 2 hours
Here’s one of those other rules we know about sunscreen - we have to reapply it after 2 hours (more often if swimming, towelling dry, sweating). So I applied SPF, then sat at my desk for 2 hours before taking another image. On average, we unconsciously touch our face 16 times/hour, so I must have been doing an awful lot of touching (the sunscreen ‘film’ also breaks down in that time, so it wasn’t ALL me!):
the take home message
I think it’s pretty clear that a dedicated SPF30+ sunscreen is the way to go (I tested a chemical sunscreen too, and it was comparable in coverage - image not shown). I will also save my beauty blender for nighttime blending. And reapplication after 2 hours will be my priority from now on!
If there are any combos you would like me to test for you, or SPF questions in general, just let me know in the comments below!
Darlington S, Williams G, et al. 2003, A randomized controlled trial to assess sunscreen application and beta carotene supplementation in the prevention of solar keratoses. Arch Dermatol, 139:451-455.
Goodman GJ, Armour KS, et al. 2018, Comparison of self-reported signs of facial ageing among caucasian women in Australia versus those in the USA, the UK and Canada, Australas J Dermatol, 59(2):108-117.
Nicas M, Best D. 2008, A study quantifying the hand-to-face contact rate and its potential application to predicting respiratory tract infection. J Occup Environm Hygiene, 5(6):347-352.
Petersen B, Wulf HC. 2014, Application of sunscreen–theory and reality. Photodermatol Photoimmunol Photomed, 30:96-10.1
Young AR, Claveau J, et al. 2017. Ultraviolet radiation and the skin: photobiology and sunscreen photoprotection. J Am Acad Derm, 76(3):s100-s109.